Archive of Our Own

Chapter Text

Hello people of Earth! My name is ♪♫♪♪♬♪♫, but I am known to humans as Rocky.

This document is one of a series I have been asked to write for historical purposes. It is a full account of my meeting with the human known as Dr Ryland Grace, and the work that we did together in the Tau Ceti system to save Sol and 40 Eridani from the Astrophage infection.

Before I begin relaying the events, I wanted to make a brief note about the translation of names. As you may know, Eridians do not produce sound in the same way that Humans do, and we are unable to imitate each other's speech. As such most Eridians who interact with Humans have a second name that they are known by to Humans. In this document I will be using "Human names" for any Eridians mentioned, which have either been agreed on by the Eridian in question, or by their closest family in the case of the deceased.

There are also many words in English that did not have equivalents in my language before we encountered Humans. During my time working with Grace I invented many new words in my language to encompass concepts from English. At the request of linguists on both of our worlds, I have included footnotes to explain my choices when creating new words.

Also, I understand that Humans process mathematics more slowly than most Eridians. In the interest of making this account as accessible as possible, I have tried to consistently use Human units when measuring time. Whenever an "hour", or a "year" is mentioned, you can rest assured that I am referring to Human hours, and Human years. If at any point I am referring to an Eridian unit of time, I will try to make this as obvious as possible.

Finally, on the subject of pronouns: It is my understanding that English, and most Human languages, have a far greater variety of pronouns than any Eridian languages do. Eridian pronouns do not differentiate between living beings and inanimate objects, nor are they specific to any "genders". I believe the closest pronouns in English to what Eridians use are "it/its".

I understand that in English Grace is referred to by the pronouns "He/Him". I have asked Grace if it would prefer I use these in documentation concerning it, but it declined. According to Grace: "I have been using Human pronouns for Eridians, it's only fair you use Eridian pronouns for me."

Chapter Text

Sometimes I'd forget.

After all these years I still don't understand that. I could remember the exact size, location, and speed of dozens of objects orbiting Tau Ceti. I could remember the exact amount of every supply remaining onboard, and how long my food supplies would last down to the hour. I could remember every item in need of repair on board the ship, a list that seemed to grow with every cycle.

And yet. Sometimes when I woke, for just the briefest moment, I would forget that I was there alone.

The room came into focus slowly as my brain warmed back up to working temperatures. It was technically the largest dormitory onboard, owing to the fact that it doubled as my workshop. In actuality it was more workshop than dormitory these days; the walls were covered in machinery and tools and equipment for my work. And when I say the walls, I mean pretty much every surface. Floors are a concept entirely defined by gravity; In Zero G, everything is a wall. The room was crammed with as much equipment as it could conceivably hold without impeding my ability to use any of it. Just about.

Only one small section of the room in the back corner was dedicated to my personal space. Once the divide had been more even, but over the years I had had to expand to meet the growing needs of the ship. My section consisted of little more than a few metal loops attached to a wall- which I was holding onto to ensure I didn't drift around while sleeping- and some fabric pockets mounted beside them which contained my few personal items.

The ship around me was quiet, as usual, the only sound was the humming of generators as they maintained my environment. Once I was warm enough to be mobile I unhooked my arms from the loops, and stretched them out. I barely avoided brushing against a rack of tools as I did so. Reorganising the workshop was somewhere on my task list. But it was a low priority, underneath all of the things in need of actual repair.

Over the years I had developed something of a morning¹ routine. After my stretches I took the time to catalogue each part of my body, mentally and physically checking myself over for any problems. There were no issues moving my arms, and a quick clench test showed no weakness in my grip. I could hear things clearly at the expected distances, and there was no unexpected pain, or dizziness, no tremors, and no deformities in my carapace.

I wasn't sure exactly what I planned to do if I discovered any of those signs. It just seemed like something I should try to be aware of as early as possible.

That done, I pushed gently away from the wall to float to my workbench, opening a drawer and removing my notepad. It was just a rectangle of malleable material, with a metal back to provide rigidity. I could make small, neat marks in it by pressing my fingers into the material, and wipe it smooth if I wanted a fresh surface. The notepad currently contained a list of every item on the ship that was in need of repair. I always made sure to review it in the morning, despite the fact that I could recall exactly what was on it without checking. This was another way of checking my health. Several of my crew mates had shown signs of confusion and memory loss as they fell ill, and although that had generally been in the later stages it was important to remain vigilant. There were always other illnesses I could develop, and there were no longer any doctors to help keep me healthy.

The list was, unfortunately, just as extensive as it had been before I fell asleep. As usual nothing had magically disappeared from it, or repaired itself in that time. Each item had a small note by it about the urgency of the repair, and how long it had been broken. One in particular had a lot of marks indicating how long it had been waiting for my attention; the engines had been operating at less than maximum efficiency for some time now. Tests indicated that the entire wiring system needed to be replaced.

I put another mark by it, to indicate that it hadn't been dealt with today. In my mind I could hear the voice of my mentor, admonishing me for leaving it alone for so long. The engines were a critical system, it reminded me. It was my duty as the engineer to keep them in perfect working condition. Once again I ignored it. The engines were only critical if they were needed to move the ship, and fabricating wires was incredibly time consuming. It could wait until I had less backlog to work through.

I picked up my tool belt, fastening it so that the tools hung under my carapace in preparation for the day. The notepad slid into its assigned pocket, so that I could take notes as I inspected the ship. Before I left the workshop, I pushed myself back towards my personal area. Opening one of the fabric pockets, I pulled out a rock from inside.

The rock was about the size of one of my fists. It was smooth, flat, and almost perfectly oval. It was built of three layers, each with a slightly different resonance, and representing an entire era of time. But none of that was what made it important. What made it important was the delicate image that had been carved into one face of it. It was a carving of the Eridani system, depicting the star and each of our 6 planets.

I delicately brushed a finger across the planet closest to the star. That was Erid. That was home. The rock had been a gift from my partner, Adrian. It had carved it for me itself, and pressed it into my hand as my crew was boarding the ship.

"I wanted you to have a little piece of home to take with you," it had said, "So you don't forget us." Its voice had been joking, but laced with the sadness and concern I knew it had felt. I had squeezed its hand gently as I accepted the gift.

"I should be the one who's worried," I had joked back, "If I'm gone too long you'll probably fill my entire workshop with new sculptures. There'll be no room for me anymore." That had been less funny than I'd intended it to be. I never had been good at finding the balance.

I allowed myself fifteen seconds to relive the moment: That last time I had felt Adrian's hand pressed against mine, those last words we had said to each other. This too is part of the routine; With enough time and practice, even grief can be folded into an efficient schedule. Then I gently closed the rock back in its pocket, and pushed away from the wall. It was time to get to work.

The ship was built into three different compartments. My dormitory was right at the back of the ship, surrounded by the engines and fuel tanks. This allowed me easy access in case something went wrong with them. The other 22 dormitories were just in front of them, in the same zone. Which meant that I had to pass them any time I wanted to access the rest of the ship.

We'd put a lot of work into the dormitories when we were designing the ship. The crew were not cargo, we couldn't just give them a shelf to sleep on and call it done. We expected to be on this mission for up to fifteen years, it was important that everyone had their own room. Obviously none of us expected to sleep alone, but that didn't mean we wouldn't want any privacy at all.

Everyone had been given a chance to provide input on the design of their own space, and we had complied as much as we could in the limited space. I had personally helped to design Zero G accommodations for Ayda, whose hearing was impaired on one side of its carapace and struggled to judge distances, and Copper, who lacked use of two of its arms. We had even designed the walls to dampen noise, allowing us a degree of privacy. It wouldn't stop someone who was intentionally listening in, but that wasn't expected to be a concern. If I didn't listen too closely, I could almost imagine them behind the doors, resting before they had to get to work.

Four corridors connected the dormitory space to the next compartment. This section was built in the shape of an octahedron, and was dedicated to the laboratory. I knew the basic function of everything in this room, and could even repair a lot of it if needed, but I lacked the understanding needed to properly use any of it. Science was not my area of expertise, a fact that had been truly driven home over the last 46 years. I drifted through it quickly, like one of the pieces of equipment was going to demand to know what I planned to do about the Astrophage problem, and continued onto the other side, where another corridor connected the lab to the control room at the very top of the ship.

Climbing through the corridor I could hear the four panels mounted on the exterior of the tunnels. These were the optical arrays; rows of mirrors that could be moved to angle light into very powerful cameras in the centre. The cameras were possibly one of the most critical pieces of equipment on the ship. Sound cannot travel through a vacuum, which meant that we couldn't hear anything beyond the hull of the ship. Getting used to that had been very challenging; after we left Erid it had felt very much like the ship was the only thing in existence. It also made it very difficult to navigate by any traditional means.

Luckily a solution had been invented a long time ago. Sound couldn't travel through a vacuum, but light could. And it had a tendency to reflect off of almost everything, creating a range of frequencies that could be detected by cameras. This was actually how Eridians learnt about the existence of stars in the first place, after someone had used a camera at the top of the very first space elevator.

The cameras were connected to consoles in the control room, which could display what the cameras detected as a tactile readout. This way we could observe the universe around the ship, so we could avoid crashing into planets. Not that that had been likely, unless we went badly off course. Very badly off course. But even without the danger of collision it was useful to have information about our surroundings.

I finally arrived in the control room, and pushed away from the door toward the control panels. These were designed to be accessible from what had once been the floor, since we needed them while we were in transit. Activating the consoles, the displays rippled, and formed the shape of the star system surrounding me.

The image was not as clear as it had once been; some of the cameras had stopped working over the years, and several of the mirrors were no longer responding to commands to move. It was all on the list, awaiting repairs. But the mirrors were mostly useful for focusing very distant light sources, and I was more concerned with my immediate surroundings. I had catalogued and analysed many of the objects in orbit around Tau Ceti, but nothing in a star system is ever static. The odds of an asteroid appearing out of nowhere and colliding with the ship was incredibly low, but unfortunately never zero. That was why I began every cycle by checking my surroundings, ensuring there was nothing approaching.

I spent a few minutes adjusting camera angles, checking on known objects and ensuring my calculations of their orbit remained accurate. I could hear no new objects in my vicinity, so it appeared I was once again safe from mysteriously appearing space rocks. The only new thing I noticed was a star that had appeared in view of Array 3. Fortunately unless it was moving at unprecedented speeds that was unlikely to be a danger to my ship any time in the next several billion years. I wondered vaguely if I was witnessing the birth of a new star, or the death of a very old one. Both events appeared very similar from a distance.

With that done, I began the arduous task of checking every system on board the ship. This was something I did every cycle, searching for any issues that might have developed while I slept. First the critical systems, then the equipment that was particularly delicate, or prone to breaking, then systems that had been waiting for repairs, and then finally all the lower priority items. The process took hours, but it had to be done.

Voyager, the person who had been chosen to head the crew, would have hated these ceaseless systems checks. It had never believed in indulging resources where they weren't necessary. I probably would have found them excessive too, at the beginning of the journey. But this ship had now been in non-stop use for over three times the planned mission length, and it had been hastily constructed to begin with. A lot of things had broken just during the journey here, and now there was no one to report any potential issues to me. It was showing its age, to say the least. I would rather waste a few hours a day on checks that turn up nothing than miss something that ended up killing me.

I found nothing new on this particular sweep, although tests showed that the engines had lost another percent of efficiency over the last few cycles. I noted that on the pad, once again suppressing the agitated memory of my mentor, before moving along.

From that point there wasn't really a routine. I would just spend whatever hours I had left before my next sleep working through my task list, fixing everything in order of priority. A power cell in the thermal system needed replacing, and then the cell would need to be repaired so it could be reused. A vent in the laboratory had accumulated too much grime, and had to be cleaned. One of the clocks was out of synch, was the power supply failing or were the gears misaligned? On and on and on and on and on it went.

Funnily enough I wasn't in the workshop when it happened, despite spending the vast majority of my time there. Instead I was in the control room, dismantling a wall panel to get at the generator. The generator was operating fine, but it had started making an annoying sound that I couldn't tune out. This wasn't really critical, and could probably have waited, but I was having a hard time focusing on anything else while it was happening. For the sake of my work, and my sanity, I had decided to make it my immediate priority.

I was just working on removing the generator from its housing when there was a sudden, loud noise from the back of the ship, where my workshop was. Where the engines were. My whole body stilled momentarily. That did not sound good.

I reached out to grab a handhold, pulling myself closer to the wall and tapping vigorously to try and hear what had just happened. The sound from the back of the ship was very unclear from this far away, especially with all the dampening we had built in, but I got the impression of things moving around. They should really not be doing that.

Despite the sudden sense of urgency I did not immediately bolt off to the workshop. There was a lot of sensitive equipment in this room, and I couldn't leave everything half dismantled while I went to investigate. I took the time to reseat the generator properly, and fix it in position, before closing the wall panel back over it and replacing the screws. Only then did I allow myself to push away from the wall and down the corridor.

There were handholds all over the ship, built with the intention of letting us "climb" around while we were in Zero G. But over the years I had found that it was much faster to just give myself a good shove in the right direction. I had gotten very good at it too, I could use just the right amount of force that I could stop myself on the far wall without injuring myself, and could take corners almost without slowing. In a matter of moments I had arrived at my workshop door.

Stopping outside, I took a moment to tap against the door, trying to listen to what was happening on the other side. It was muffled, but I could definitely hear a lot of things drifting around the room. How had that happened? I could at least confidently say that the hull had not been breached, but there was a lot that could go wrong without that happening. There was nothing else for it, I needed to go in and assess the situation.

It took me a moment to make sense of the scene I found inside when the door slid open. None of the machinery had moved thankfully, it was all safely bolted in place. But there were a lot of smaller boxes and drawers floating around, their contents distributed around the room. Nuts, screws, various smaller tools and things were bouncing around, dinging off of every surface in a way that made me nervous for the more delicate machines. I had to come inside quickly and close the door so that nothing could escape. It was an absolute mess.

It didn't take too long to follow the path of calamity, and realise what had happened. Along the exterior wall were several pipes that controlled the flow of ammonia around the ship. The screws holding one of them together had come loose, releasing a pressurised stream of ammonia. The leak had stopped, the pipes were designed with valves that would shut in the event of pressure loss, but the sudden burst had dislodged some of the storage units that had been nearby, causing the contents to go flying.

For a moment I just floated there, feeling a little dumbfounded. How had this happened? Didn't I inspect the ship every cycle? Didn't I test every single system? Meticulously list everything that needed even minor repairs? How had a pipe managed to fail without me realising that was going to happen?

But that was a ridiculous question. I couldn't check every single screw, every single cycle. There would never be time to do anything else. Everything in the ship was organised by priorities, everything checked in a time and order decided by how critical they were. With newer higher priority things constantly popping up, some things had evidently slipped through the cracks. My meticulous system had failed.

I reached out and grabbed a nearby handhold, forcing myself to calm down. I couldn't get worked up over this. The equipment here hadn't actually failed, it had just broken. Things were breaking on the ship constantly, that's why I was here. This one had broken more loudly than most things, but it wasn't actually a critical issue.

The systems had done their job, I reminded myself. That pipe was part of a tertiary system, the back up of a back up for the atmospheric regulation system. And the fail-safes had worked exactly as intended, preventing major pressure loss. All this had really done was make a mess of my workshop, and that was easily remedied. This was simply an annoying hour taken out of my cycle to tidy up and replace the screw on the pipe.

Just then a piece of debris came past me. It was a very familiar piece of debris. A smooth oval rock, the size of one of my fists. Instinctively I reached out and snatched it from the air, before it could get away. The blast must have thrown it against a hard surface, or thrown a tool into it or something, because there was now a rough chunk missing from its perfect, polished surface. A harsh wound cut out of my little piece of home.

I turned to rock over, so it was face up in my hand, and reached to touch this new texture. Then I stopped, as I realised my hand was shaking. Instead I moved myself over to my sleeping area, and carefully tucked the rock back into its usual pocket. The missing piece wasn't in there, it must have been knocked out with the rest of it during the incident. I secured the flap back down, then gently gripped one of the metal loops and slowly pulled myself to it. I hooked my arms through the loops like I was about to sleep, even though I had only woken a few hours ago.

There was something building up inside me. I felt like a bubble, pressure held together only by surface tension. Very gently, I used the leverage of the loops to rock myself back and forth, humming a tuneless hum. I thought that if I moved too fast I was going to burst.

This wasn't how Eridians were supposed to sleep. We didn't evolve worrying about floating away. We had evolved on a planet, with gravity, on solid ground. On Erid, I would have slept on a soft nest of blankets. I would have curled my arms up underneath me, resting my carapace atop them. I would have been able to hear Adrian going about its work as it prepared to watch over my helpless body. But none of that was possible here.

The rocking picked up momentum. I wasn't being careful enough, I knew. The thing inside me was growing, the pressure building higher and higher. If I wasn't careful it would overtake me. It would consume first me, then the ship, then Tau Ceti, then maybe the entire galaxy in a terrible, beautiful moment of totality. It would consume my star before the Astrophage could, and my whole world, and all the things I loved and wanted to protect. And maybe, once that was all gone, I could finally rest.

It wasn't fair. It just wasn't fair. There were twenty-two other Eridians on the ship when we left. If any one of them had survived, if any of them other than me had survived, they could have done this. They would have found a solution, brought it home, and I could have rested peacefully knowing that our world was safe in their hands. Why was it me. Why was it me.

I stayed there for hours, waiting for the universe to fall apart around me. But it didn't. Things drifted around the room, occasionally bumping into me. The ship's generators hummed around the ship, maintaining my environment and all the equipment. Outside Tau Ceti kept burning, and everything in the system continued its endless fall around it. Eventually the thing inside me began to slowly deflate, leaving me feeling hollow. I was still here, and there was still work to be done.

In the end, three full cycles passed before I could return to my usual routine. After I had cleaned up my workshop, and replaced the screw that had failed, I committed to checking every single screw, bolt, and bracket that was part of a critical ship system. It was a pretty big ship, and this was a laborious and not very interesting task, but I refused to shift my focus from it until it was done. I had been very lucky that it was only a tertiary system that had failed, and it had done so in a way that only caused superficial damage. I was not going to get caught out by it again.

In retrospect, the mistake I had made was expecting conditions not to change. I had left the rock in the pocket by my sleeping area, expecting it to keep being safe there. I had left the pipe in my workshop alone, expecting it to remain in working condition. I had settled into a routine, expecting nothing to disrupt it.

But nothing stays the same just because you left it alone. Even in the vast, empty expanse of space things were constantly in motion. Stars were born and died. Asteroids streaked across unknowable distances. The planets orbited endlessly around the star, which orbited endlessly around the centre of the galaxy, which orbited endlessly around some great mystery at the centre of everything. Everything in the universe tended toward entropy, driven by change. And when I finally checked the optical arrays again, three cycles later, that was exactly what I saw.

Outside, something had changed.

Chapter Text

It wasn't a star.

I kept thinking that as I listened to the readout, trying desperately to make sense of what I was hearing. That wasn't a star. It couldn't be. Could it?

I paced back and forth in front of the consoles. This was harder than it sounds, because Zero G really didn't accommodate traditional pacing. I had to climb back and forth along the handholds, which was actually not very similar at all. But this was a situation that required pacing, and this was the only way I could approximate it. My mind was racing with the possibilities, and I was scrambling to bring them under control.

The point of light I had noticed three cycles ago had gotten noticeably brighter in the time I had been busy replacing screws. In fact, it was now so bright that it was outshining all the stars surrounding it. That was a very large increase in luminosity over a brief window of time.

Astronomy wasn't something I knew a lot about, but the crew had been required to learn some of the basics before leaving. I knew that when a star died it became a supernova, which emitted more light than the original star did. I also knew that sometimes it took time before it reached its full luminance. That could be what I was seeing now: a dying star releasing its final light into the universe.

The problem with that was the visibility. The light, if it was from a supernova, would either have to be very large or relatively close to be appearing so brightly now. So why hadn't I heard a star in that area before? A supernova was brighter than the original star, yes, but was it that much brighter? So much brighter it could go from not being visible at all to being brighter than everything in the sky around it?

I paced more aggressively, pulling myself so hard that I was at risk of launching myself away from the handholds. There was another conclusion I could draw from this. I just wasn't sure I was willing to entertain it.

Because it was possible that the point of light wasn't getting brighter at all. It was possible it just appeared brighter, because the source was getting closer. But for that to be the case, it would have to be a light source as bright as a star, moving at incredible speeds. There was only one thing I could think of that would meet those criteria. Something that I was very familiar with, because I had helped to build it. Something I had been stuck living on for the last 46 years.

For a moment, when I'd first noticed the increased brightness, all I could think was that they had sent another mission. That Erid had built a new ship, and sent it after me. That made a kind of sense; I had been out of contact for a very long time, and barring any major technological advances there was no other way for them to learn why Tau Ceti wasn't being consumed by the Astrophage.

I had lived with the very confusing concoction of emotions that thought had raised for all of a few seconds before I realised that couldn't possibly be the case. Even with my limited understanding of astronomy, I was pretty certain that the light was coming from almost the opposite direction to Erid. Unless it had taken a decades long detour for some reason, there was no way an Eridian ship could be approaching from that angle.

Which meant it wasn't an Eridian ship. But did that mean it wasn't a ship? Or did it mean it was a ship from somewhere else? But that was ridiculous, wasn't it?

Fake pacing was no longer sufficient, so I began bouncing from wall to wall. It was a very long leap to go from "This star has increased in luminoisty an unusual amount" to "there's an alien spaceship heading towards Tau Ceti". Was I really prepared to make that kind of a leap?

I'd never given very much thought to the idea of alien life. Or rather, I'd given quite a lot of thought to one specific alien life form. But I'd never considered the possibility of others. I certainly hadn't given any thought to the idea of alien life forms intelligent enough to build their own ship and go traveling through the universe. It wasn't even like I had very much to go on here. No, I don't remember a star being there, but does that mean there never was? the cameras weren't exactly functioning optimally right now, maybe there had always been a star and I hadn't been able to see it recently because the mirrors weren't focusing enough light onto the camera. Maybe I had just forgotten.

Then I had a sudden realisation. The cameras took in as much light as possible from the surroundings, but the readouts could be configured to only display certain frequencies. That was very useful when locating the Astrophage migration line, because while stars and supernovas emitted a very broad spectrum of light, Astrophage only emitted one very specific frequency. If I configured the readouts to look for that, then a supernova would become much less visible, while a light created by Astrophage would be unchanged.

Good. Great. That was an easy way to disprove that theory. I halted my bouncing, pushing once more and catching myself on the console. Good. I just had to do it. My fingers hesitated over the controls, shaking ever so slightly. Calm down, I told myself. Calm down.

Steeling my nerves I pushed forward, altering the settings to display only Astrophage light frequencies. After a moment the screen adjusted, the endless sky of stars smoothing out and turning the screen almost entirely blank. Almost. Right there in the middle, as present as it had been moments before, the thing that was definitely not a supernova remained. That was Astrophage. That was a ship.

I might have possibly freaked out a little at that point. There may possibly have been some screaming. But in my defense: Aliens!!! Intelligent aliens!!! This was not a scenario we had prepared for. If it had happened on Erid almost every scientist on the planet would be gathering to thrum about it, and decide what to do next. Instead it was just me, trying desperately to wrangle my own thoughts into something cohesive.

Focus on the facts, I told myself. That was Astrophage. And it was definitely getting closer. Astrophage didn't just do that. The only time it was actively moving, and not just drifting, was when it was migrating between a star and a carbon dioxide rich planet. So it had to be a ship, right? A ship using Astrophage as fuel, travelling toward Tau Ceti.

Was I getting ahead of myself? Was there any reason to think this was the destination? Maybe. This wasn't just a random point in space, Erid had sent the mission here specifically to study Astrophage. The ship, assuming it was a ship, was using Astrophage as a fuel source, so it seemed likely that their star had also been exposed to it. So it would make sense that they would also be interested in Tau Ceti. These were all assumptions, yes, but not entirely unfounded ones. Maybe they were in the same situation we were, and were coming to Tau Ceti to find the same solution.

The pain I felt at that thought was so intense, and so unexpected, that my arms would probably have given out under me if there had been any gravity. Or maybe pain was the wrong word. It was more like longing. Longing so powerful and overwhelming that it felt like pain.

Maybe that alien ship was full of scientists. Real scientists, who knew what they were doing, who knew who to study Astrophage. What if they could help me? What if we could find an answer together, and I could bring it home.

My whole body was shaking. I wasn't even sure when that had started. How long had it been? When was the last time I'd had a reason, any reason at all to hope? It was surprisingly painful to do it again. Like all the hope had been sealed away in some secret part of me, and now it was being forcefully ripped back out.

I could still be wrong. I didn't want to hope for this and be wrong. But I had been carrying this insurmountable burden for so very, very long. The idea that someone, anyone, might be able to take it from me, that all my time here might not have been for nothing, was too overwhelming to suppress. I wanted to scream. I wanted to sing. I wanted to curl up at the hands of someone better than me and beg them to save my people. I wanted to sleep for years, and years, and years. I wanted to wake up at home.

It took a long time to calm down enough to think coherently again. The readout remained the same, showing me that bright light. I reached out and stroked a finger gently against it, feeling the display give slightly at my touch. If I was wrong, then nothing that I did about it would matter. It wouldn't change anything. But if I was right, if there was any chance I was right, then I needed to get ready. There was a lot to do if I was going to be able to greet this ship, and there was only me to do it.

If I ever got to design a spaceship again I was going to find a way to accommodate fidgeting in a weightless environment. There had to be a way to pace effectively in Zero G, and I was going to find it.

It had been eight cycles since my revelation about potential intelligent alien life in the universe, and a few things had become clear over this time:

1) It was definitely a ship. The light had continued getting brighter past the point where I could possibly explain it by any natural phenomena. I couldn't see the ship because they were apparently thrusting in my direction, presumably to decelerate on approach to the star. And to that point:

2) They were definitely approaching Tau Ceti. It had been a nerve wrecking few cycles while I waited to see if it was actually heading this way, or was going to shoot past the system, but at this point I could definitively say that the ship was within the Tau Ceti system. Technically they could keep going straight back out of it, but there was no reason to be this close to a star unless it was the intended destination. This star system alone was billions of kilometers in diameter, and that was a tiny fraction of the distance between Tau Ceti and its closest neighbour. It wasn't like it would be hard to avoid flying through star systems, and it would make it easier to avoid the debris that gathered around stars.

3) Eight cycles was not enough time to be ready for this. I wasn't sure any amount of time would have made me ready for this. I was not ready for this. This particular point was only really occurring to me now, as I listened intently to the readout to see where the ship stopped.

The last eight cycles had been a whirl of activity while I worked to prepare. My neatly organised list was entirely upended as priorities shifted very suddenly. The engines were no longer something that could wait, I needed them fully functional so that I could meet the ship wherever it stopped. The cameras in array 3 needed to be optimised so I could gather as much information about the ship as possible. I had to think about how I was going to communicate for the first time with an alien species.

It wasn't as though we were going to have any language in common. We probably weren't even going to have any anatomy in common. Could aliens even talk? Who knew. They certainly weren't going to understand any written messages I sent them. I had spent cycles agonising over what I could possibly convey to them that I would be sure they could understand.

In the end, I determined two things I could be absolutely certain we both knew about: Stars and Astrophage. The ship was using Astrophage as a fuel, so the aliens must have at least some understanding of what it was. And they had identified Tau Ceti as important and navigated a ship here, so they must at least know about the local stars. So I based my message around that.

I created a model out of xenonite. It was a map of all the local stars, using thin whiskers to attach them to a base. I made the centre of the model Tau Ceti, which seemed like a good reference point since we were both here, and made an addition to the star. Another small whisker of xenonite, in the shape of the Astrophage migration line, ending in a tiny little ball to represent the planet that Astrophage was migrating to. I made a similar addition to one other star on the map: Eridani, with a little ball to represent the third planet from the star. I hoped that the message would be clear. "This is where we are, and this is where I came from". I just hoped my model included the star the aliens called home.

At the time I had felt like I'd done a good job preparing to greet this new species. Now, listening to the light get bigger and bigger on my screen, everything I had done felt woefully inadequate. What was I going to do? Just stop my ship next to them and shoot my message, contained in a xenonite capsule, at them? What kind of way was that to greet people? What if they didn't want it? What if they thought I was being aggressive? How do you tell an alien you can't communicate with that you mean them no harm? Did they mean me no harm? I had no reason to think they'd come here for a fight, but I didn't know.

Such were my thoughts as I bounced and fidgeted around the control room. I had to try, didn't I? But what if I messed up? What if we ended up estranged from the first intelligent aliens we'd ever discovered because I did a bad job socialising? That seemed terrifyingly likely; I'd never been the most socially adept Eridian. We hadn't thought to select someone for this kind of thing for the crew. Not that it would have mattered if we had, I supposed. I pushed that thought away before it could sink in too much.

Then the light on the screen disappeared. I froze mid-bounce, which unfortunately meant that my momentum carried me very ungracefully into a wall. At least the aliens hadn't heard that.

I scrambled to the controls, focusing on the point where the light had been before vanishing. The star system, as I've mentioned, was pretty big. There was never any real chance that they were going to stop right by me. They probably wouldn't even be able to see my ship unless they were specifically looking for it. I adjusted some controls, moving the mirrors in array 3 to direct as much light as possible from that area to the camera. It took a few minutes, but then the screen changed ever so slightly. A tiny point of light, reflected from the star. It was either the ship, or an extremely coincidentally located asteroid in the same area as it. I would take my chances on it being the ship.

So this was it. Time for first contact. I waited a while before making any move towards the ship. When I'd first arrived here, I had a difficult time getting into the system successfully. Our arrival projections had been so far off that I almost couldn't believe it, except that it had been happening to me. It had taken a lot of stopping and starting and trying again before I had successfully navigated into the Tau Ceti system. This ship seemed to have had a much easier time; I hadn't noticed any changes that would indicate they were making significant course corrections. Once I had waited long enough that it seemed they were well and truly stopped, I decided it was time to act.

For the first time in a long time, I brought the engines to life. My placement in the system was fortunate; if the aliens were searching for the Astrophage migration, then they may well hear the light of my engines as I approached them. I was hoping so anyway, or I would have a difficult time figuring out how to get their attention. The last thing I wanted to do was accidentally sneak up on them.

Moving very carefully- I did not want to crash into the aliens, or vaporise their ship with my engines- I approached the contact point. As I drew closer, I finally began to get some information on this ship.

The first thing that I learnt about it was that it was small. Once it was on my radar and I could finally determine its distance from my ship, I realised that it was probably only about a third the size that mine was. Were the aliens very small? Or was it just a smaller crew? On Erid we had wanted to bring as many people as possible, fulfilling as many roles on the ship as we could. There were a lot of scientists, yes, but also an enigneer (me), two doctors, astronomers, and Voyager to manage everyone. But I didn't know how these aliens worked. Maybe a smaller crew was considered more optimal for whatever reason. Or maybe they were really tiny. Or maybe their species was just one incredibly intelligent individual who was thousands of years old and had mastered every conceivable craft. It was really difficult to suppress the urge to speculate wildly.

The next thing I learnt was that they really liked curved surfaces. The ship was basically a long tube that came to a point at one end, and flared out to be much wider at the other. There was a big ring around the middle of it too, which I couldn't begin to guess at the purpose of. I found the design interesting; those curved pieces would have been more difficult to manufacture than plain flat panels, and would need more precise engineering to fit together accurately. Maybe they were interested in optimising the volume of the ship?

What I couldn't hear was any kind of railing system for a hull mounted robot. I had been hoping there'd be one I could aim my capsule at, to make it easy for them to catch. Because the only way I was going to get it over there was by throwing it, it wasn't like I could go knock on their door in person. But why no robot? Presumably they'd want to access things outside the ship, especially if they were going to get an Astrophage sample. Was it just very well hidden? Or did they have some other way to retrieve things?

I brought my ship to a stop 217 metres away from the alien ship. Well, I matched the ship's velocity. Neither of us were actually stationary, we were orbiting around Tau Ceti, but our velocity relative to each other was zero. 217 metres was about one and a half times the length of my own ship, which seemed like a reasonable amount of space to give them. And then I waited. I had done the first part, bringing myself to their ship. Now I needed them to acknowledge my presence somehow before we could proceed.

The seconds crawled by, with no response. Had they heard me? They must have a way of observing outside the ship, right? They had to have navigated here somehow. And they would need some way to study their surroundings. Were they just not doing it right now? But why wouldn't they? They just got here, they must at least be curious-

The alien ship's engine flared to life. Just for a moment, and with only a fraction of the power it had displayed previously, and then it was out again. I checked my readouts; it was now moving at 8.6cm/s relative to me. Had that been for me? Was that its way of letting me know it had heard me?

I decided to assume it was intended for me. The next step from there seemed obvious. I tapped some buttoned and flipped some switches, activating the engines for exactly as long as the other ship had, just enough enough to match our velocities again. My fingers were shaking from excitement and nervousness.

The other ship's engine flared again. Three short bursts, a long burst, and one more short burst. A small squeak escaped me, but I quickly got myself under control. There was no way that was for a maneuver, the ship hadn't changed directions at all. That was definitely intended for me. This time I was quicker on the controls, and I copied the pattern exactly. Yes, I thought, I hear you. And now I knew they could hear me.

Okay, exciting as this was I couldn't spend all cycle playing mimic. I fired the engines again, this time returning myself to the position 217 metres from the ship. Now it was time for the real message.

The hull robot had a couple of different control mechanisms. It was built with five arms, each ending in a hand, for manipulating things. I could give it some generic commands from the control panels, but for finer movements there were the gloves.

They weren't gloves in the traditional sense, it was basically some rings joined by articulated metal rods, with wires running all through them. I could slip my fingers through the rings, and whichever robot hand was being commanded would copy whatever movements I made with my hands. I could control up to four of them at a time this way, since I needed at least one hand free to anchor myself to a handhold, but at this moment I only needed one.

I had handed off my capsule to the robot earlier, in preparation for this moment, and now I steered it until it was facing the alien ship. With no apparent robot or retrieval system to aim at, I decided to play it safe. Very, very gently, I released the capsule, aiming right for the centre of the ship. In a last minute decision, I set it moving at 8.6cm/s, the same speed the ship had moved when it first fired the engine. It meant that it would take a while to reach them, but it would give them time to prepare for it, and it was a speed I knew for certain they were comfortable moving at.

The release was almost perfect, with a slight end over end rotation. I could hear the regular glint on the readout as the ends caught the light from Tau Ceti. Then I turned my attention to the other ship.

Nothing happened for a few minutes. I had that long to wonder if the aliens were even going to bother. What if they had decided to just ignore me? It wasn't as though I could do anything about it if they did, besides scream a lot. I wriggled and fidgeted, but didn't move my focus away from the ship. I was willing something to happen.

And then it did! A door opened, toward the pointed end of the ship. I immediately perked up, adjusting my cameras to focus on that area. A figure was emerging from the ship. It was large, compared to an Eridian. Perhaps two or three times our size. It had a vaguely oblong midsection, attached to which were looking like four long, thick "arms", and a sphere shaped protuberance. From the direction I was looking at it it had a large rectangular structure behind it. Was this the device they were sending out to retrieve the capsule? Why did it look like that?

As I watched, the figure made its way out of what I presumed to be an airlock. I realised that it was attached to the inside of the airlock by a tether. As it moved, it attached a second tether to a point on the exterior of the ship, and then waited there a moment, turning this way and that. I hummed with confusion. Why would anyone design a robot that way? What was the sense in storing it inside the ship, and not having it directly attached to it? And how did they even control such complicated movements-

Oh. No. No way.

With a dawning sense of fascinated horror, I began to realise that that might not be a robot I was looking at. After a few minutes of waiting it began moving towards where the capsule would arrive. It used two of its arms to move itself along the hull, and two to manage its tethers, so that there was always one attached to the ship as it moved forward. It would have been incredibly impressive but very poorly designed if it was a robot. Impressive in that it was demonstrating incredible fine motor control, and poorly designed in that it would be in massive danger of simply drifting away from the ship. But that was exactly the kind of dexterity and autonomy of movement I would expect from a sentient, living entity.

I was reasonably certain I had just had my first look at an intelligent alien, and it was wandering around outside of its ship.

I had a million questions. Primarily, why? Why would anyone do that? But also, how? Presumably what I was seeing was some kind of life support vessel, one that was designed to allow the user to receive information about its environment and move around autonomously. How did that work? Were there readouts inside the vessel? How did they fit them in? Was that what the alien creature inside was shaped like?

The alien- that's an alien I'm looking at an alien- reached its position, about halfway along the ship, and waited for the arrival of the capsule. It had positioned itself so that two of its arms were resting against the hull. Those arms were slightly different from the two it used for the tethers. The hullward arms ended in a solid lump, while the others ended in what sounded to me like five-fingered hands. There was no rotational symmetry to it at all, although one side of it did seem to mirror the other. I desperately wished there was some kind of gravity, so I could listen to how it moved in its normal environment.

The capsule finally drew close to the alien. It took its time, waiting for the capsule to be fully within reach before grabbing it with both of its "hands". I let out a small squeal of excitement, and then felt embarrassed about it. Then I decided it was fine actually, and squealed some more. We'd done it! I'd passed my message to the alien, and it had caught it! This was probably one of the most exciting moments in my history. I wished so badly that the others were hear to share it with me. Mycellium, the lead biologist, would have been scrambling to learn more about this new species. So would the rest of the biology team, and the doctors. Voyager would have been ecstatic about the idea of another world full of sentient life. Everyone would have been so excited.

The grief was surprisingly fresh, in a way it hadn't been for a long time. I suppose it had been a while since I'd last had a new context for it. An entire ship full of scientists, and the one left to meet this new alien species was me. It really wasn't fair. On the screen, I could hear the alien making its way back to the airlock door, the capsule grasped tightly with one of its arms. It was moving a little faster than before, hurrying back to the ship in a way that made me concerned for its safety. But presumably it was aware of the risks, and of what its body was capable of.

My crew wasn't here to share this, so I was just going to have to carry all of this for them. Their excitement, their wonder. Their hope. It was the least I owed them. As the alien re-entered its ship, disappearing behind the closing door, I wriggled in anticipation. It's your turn now, I thought. Let's see what you make of it.

Chapter Text

The ship was spinning now. That was interesting.

I'd had a moment of confused panic when the alien ship began splitting in half, minutes after the figure had re-entered it. The idea that my capsule might somehow be harmful to the aliens was something I'd debated myself over for hours before I'd made it. I didn't know anything about these aliens, I didn't know their biology, their environment, or the composition of their ship. Sure, Xenonite is typically a non-reactive material, but could I be absolutely certain that it wasn't harmful to them somehow? And what about my atmosphere? What if ammonia was bad for aliens?

In the end I had decided that the only way to proceed was to have some faith in these fellow space-farers. This was a species intelligent enough to build ships and travel through the stars, they were probably prepared to take some basic safety precautions when dealing with an alien material. They probably had some kind of procedure to isolate it safely until proper tests were performed on it. That had seemed like a very sound argument, right up until the ship began breaking in two.

Thankfully it quickly became clear that this was some kind of intended function of the ship. The motions were too smooth and controlled to be anything else. One end of the ship, the one that the alien had exited and entered through, began turning so that its pointed end faced the other half. As they separated they were kept connected by long, thick cables, which slowly unspooled from somewhere. Maybe from that big ring around the middle of the ship. They continued separating until the entire structure was 104 metres long, more than twice its original length of 49 metres. And it was spinning.

Was this another message somehow? Maybe I was supposed to copy it again? That seemed unnecessary, we had already established communications of a sort. I decided I should copy it anyway, just in case.

The alien ship was turning a full arc every 17.38 seconds, so I aimed to gradually increase to that speed. The ship wasn't really made for that motion, but after some adjustments with the controls I managed to get it turning. It wasn't as smooth a process as the other ship, which probably had a better weight distribution for this, but it would do.

As the speed slowly increased, I realised I was being drawn towards what would once have been the ceiling of the control room. Ah. Centrifugal force. I grabbed onto a handhold by the console, so I could be close enough to adjust things if the force started getting too strong. It didn't though. After a couple of minutes the ship reached the target speed, and I shut off the thrusters.

The force was fairly weak, probably less than half of Erid's gravity. But it was gravity. I hadn't felt gravity in years. Well, there had been a brief force while I was moving to meet the alien ship, but that had been very brief and I had been very preoccupied.

I checked the walls quickly, to make sure there was a path of handholds I could use to reach the consoles, and then I released my grip and allowed myself to drop gently to the new floor. I tested the force, bouncing on my arms and jumping up, shifting my weight from side to side. A squeal of excitement escaped me, I couldn't help it. There was gravity!

For a few minutes I almost completely forgot about the alien ship, and relished the simple luxury of having a floor. It made something settle in my that I hadn't known was loose, as I skittered and rolled in sheer delight. Back on Erid, before the Astrophage crisis, I had been one of the engineers responsible for maintaining the space elevator, among other things. The space elevator descends very quickly, enough so that the people inside it experience less than normal gravity. This reminded me of that feeling. It was familiar enough that I could almost imagine I was there, if I hadn't been able to hear the rest of the ship around me.

Memories flooded over me unexpectedly. My first time ascending the elevator and visiting the observatory. Hearing stars for the first time through the equipment. Meeting with other scientists and engineers, talking and laughing over work and sharing ideas. Designing and building new things, and helping to maintain what was already there. The fateful day we had learnt about Astrophage.

It had been while walking home from the elevator that I had first met Adrian. It had been digging around the bottom of a nearby hill, and I had stopped to ask what it was doing. Adrian explained that there were a lot of good rocks in this area, and it was collecting some for its art work.

I hadn't know there were good rocks and bad rocks before Adrian told me about them that day, cramming as much information about it as it could into a six minute conversation with a total stranger. Apparently some rocks are good for engraving, but don't lend well to carving. And the way they form affects their sound, which affects the tone of the finished piece. And some are structurally interesting but not really well suited to being reshaped.

Of course after listening to all that I couldn't not help it search, so over the next few hours I had learnt more about rocks than I'd ever known there was to know about them. And by the time I had helped it carry its haul home, I had desperately needed to spend the rest of my life being told about rocks.

Thinking about Adrian brought an ache I had come to know very well in my time here. But somehow, in this familiar sort-of-gravity, it didn't feel quite as sharp as it usually did.

I settled myself on the floor, curling up my arms into a nest and resting my carapace on top. It was a simple gesture, and comforting beyond words. For the first time in years, I felt like I was at rest. I probably could have stared there for cycles, drifting through memories.

But I wasn't alone here now. After a while of peaceful reminiscing, I heard the flare of the alien ship's engines on the console display. I unfolded my arms, shaking off my restful state, and climbed back up to the console. The other ship was countering its spin, gradually bringing itself to a halt. It sounded like it was time to continue our conversation. With a few movements I adjusted the controls, and began slowing my own rotation. Before long both ships had stopped spinning, and we were once again motionless relative to each other. I drifted weightlessly again, held in place by my grip on the handhold. It was nice while it lasted.

Soon after stopping, the airlock door of the alien ship opened again. There was the creature again, floating in the airlock, kept from drifting away by the tether attached to its vessel, and the hand it used to hold onto something on the wall. I still had no idea how it was getting information about the environment from in there. What I wouldn't give to have a vessel I could take apart and study. But that was probably not the best way to introduce myself to this new species. Maybe when we'd gotten to know each other it would let me dissect some of its technology.

The alien didn't fully exit into space this time. Instead it held up the capsule, the same one I had sent it, and threw it towards my ship. The radar showed that it was moving quite a bit faster than when I had sent it. I hummed excitedly; This was good! It was demonstrating that it was comfortable with a faster delivery. We were communicating, and that was thrilling. Calculating quickly where it was going to arrive, I donned the glove once more and moved the hull robot to meet it. By the time I had done this, the alien and closed the door again.

I watched the door for a while, in case it emerged again. But it seemed that it wasn't inclined to hang around outside any longer than it needed to. That seemed sensible. Even if you were very confident in your technology it probably wasn't terribly safe.

The capsule floated into range, and landed perfectly in the robot's grasp. I was so excited I almost let go of the thing again. There might be a response from the aliens inside that capsule! Every new thing that happened was so exciting, I couldn't imagine the novelty ever wearing off.

I piloted the hull robot around the ship once again, bringing it to the airlock that attached to the laboratory. Putting the airlock in the lab had been a matter of efficiency; Most of the things we would want to bring into the ship were for the scientists to analyse, so it made sense for it to go where that would happen. Once the door was closed, and the airlock began re-pressurising, I skittered down to the lab to inspect the cargo.

This was probably the riskiest part of this endeavour. There was no way to know what the aliens had sent over, and therefore no way to know if it might interact badly with my atmosphere. I couldn't check what it was before bringing it into the ship, so I was mostly just hoping that whatever it was was not about to explode in my airlock. Not that that was likely, but once that becomes even a very slight statistical possibility it's a little difficult not to think about.

I had done what I could to mitigate potential atmospheric contamination. The capsule had a small hole in the top and bottom, allowing any air to leak out over the course of its journey between ships. That was actually also important in case there was a difference in air density: If the atmosphere contained in the capsule was less dense than that atmosphere surrounding it, it would be incredibly difficult or even impossible to open. If the atmosphere inside was much denser than it would explosively decompress on opening, turning the capsule halves into small missiles. Having the holes in the capsule allowed it to immediately equalise with the new environment, as well as meaning we didn't have to deal with gases from each other's atmospheres.

But I still couldn't be certain all the molecules would have emptied out. Physics rarely works as neatly as it should in theory. That's not even mentioning any materials that might have been deliberately added to the capsule.

Arriving at the lab, I hurried over to the controls for the airlock. The hull robot was in there, capsule gripped in its hand. The room had already begun repressurising, and I tapped eagerly against the door. The sound was quiet in the low pressure of the airlock, but I recognised the sound of the model I had sent earlier. As more and more ammonia poured in, I realised that something else had been added on there. I wriggled and squeaked with excitement. I really, really wanted to get my hands on it but I forced myself to be patient.

There was no explosion as the airlock reached full pressure, which was a good start. I allowed the capsule to remain inside for 25.55 agonising minutes, in case there were any slower reactions occurring. After there were no obvious developments I ran some quick tests on the air inside the airlock. It still appeared to be 100% ammonia, so it seemed that the gas had successfully escaped during its journey, and whatever was inside was not reacting to my atmosphere. That was about as certain as I could be that it was safe to bring fully inside.

The airlock door was controlled by a lever on the wall beside it. I grabbed onto a handhold near the lever and pulled down. With a series of clunks and groans the locks disengaged and the seals released, allowing the door to swing inwards. And there was the capsule, still gripped in the robot's hand.

I skittered up to it, gently taking it from the robot and scraping my fingers down the sides of it. The additions inside were clumsy, compared to the rest of the model. But that didn't matter, what mattered was what the intelligent alien species had wanted to tell me. Twisting the capsule open, I very gently tipped the model out, and picked it up from where it hung suspending in the air. On one of the other stars, one on nearly the opposite side of the model from Eridani, was a new Astrophage migration line.

Another squeal escaped me as I took it in. The altered star was about sixteen light years away from Eridani, and about thirteen from Tau Ceti. That was the home of this alien species. Gently, I reached out and touched the new line. And it came off on my finger. Whoops.

Whatever the aliens had made the line out of was not fully solid in my atmosphere. The moment I had touched it it deformed, leaving a smudge on my finger. Listening more closely, I realised that there had been a globule of something else floating around too. Presumably that had also been attached to the module. Maybe the alien had tried to add a planet, like I had, but the material had completely melted.

I got both of the materials contained (loose liquids on a space ship is a bad, bad idea. If they get into any of the electronics there's no telling how it might interfere). This too was interesting information. The aliens had probably intended those materials to be solid, which suggested they were being used in a much cooler environment than mine. Possibly quite a lot cooler. Maybe too cold for our environments to be compatible with each other. That might complicate things a little.

The next hour or so was spent analysing and modelling. The metal used to make the Astrophage migration line was an alloy of tin and lead. The other material was a hydrogen and carbon compound. Unfortunately I couldn't glean much information from that; I'm an engineer, not a chemist. Based on experience I could estimate the melting point of the alloy to be somewhere in the 180-230º Celsius range. depending on the ratios involved, but I couldn't begin to guess at the properties of the other compound.

I spent most of the time designing and building the next model. This one featured both of our ships, the alien ship dwarfed in comparison to mine, connected by a small xenonite corridor attached to our airlocks. There was only one way that we could proceed with this. We needed to meet in person.

It was, admittedly, a risky move. And it was possible I was letting my own eagerness cloud my judgement. But also, we couldn't not try to meet, could we? If I was right, and we were here for the same reason, then I desperately needed their help. Having access to actual scientists, even if I couldn't understand them, and even if their science was vastly different, was worth the risks.

They seemed friendly enough. They had signaled me to let me know they'd noticed me, and responded to my message. That probably meant they were at least open to communicating, and possibly collaborating. I could take care of connecting the ships, I had enough information and material to make the tunnel. All I needed to know was what their hull was made of, and if they were willing to let me do it.

Once the model was finished, and screwed into the capsule (I was reusing the same one, there was no reason to waste material), I handed it over to the hull robot, and headed to the control room. This time I knew where the alien was exiting from, so I decided to save them some time by aiming directly at it.

The alien had sent the capsule back faster than I had sent it, so I matched its speed again. The hull robot released the capsule, once again turning end over end as it zipped through the void. At this speed it would only take a few minutes to arrive. I really hoped the aliens were watching out for it.

Soon after, the aliens' airlock door opened again. The figure was in there, floating just before the exit. It waited at the side, seeming to follow the movement of the capsule with the smooth plate on the front of the sphere at the top of the vessel. I wondered if that was where it was getting its sensory readings from. Perhaps it was designed to detect light, the way my cameras were? I dearly hoped we'd have some time to discuss its technology once we had established proper communications.

The capsule floated into the airlock, and I hummed in satisfaction as it flew directly through the middle of the opening. It wasn't the most challenging calculation, but it was still satisfying to see a perfectly executed delivery. The alien tracked it until it was fully in the ship, and then turned its smooth plate back towards my ship. Then it raised one of its arms, one of the ones that had hands at the end, and waved it side to side.

Oh, I thought. That's a person.

Not that I'd been thinking of it is not a person. But there had been something so distinctly... Eridian about that gesture. A small hand wave to express, what? Approval? Excitement? Just plain friendliness? It was a gesture that would have fit in with all the thousand such gestures that people made every day back on Erid. It reminded me so much of home that it hurt.

I raised a hand and waved softly back at the readout, but of course the alien couldn't hear me. It pulled something on the wall, and the airlock door closed again, leaving me alone. But it was okay. We'd have time for proper greetings if this all went well.

If watching an alien exit its spaceship had been morbidly fascinating, I didn't have words for the feeling of watching it knock a piece off of its own hull. Not that I didn't understand the intention of it. If you could ignore how horrifying it was it was actually very useful. I needed to know what its hull was made of to ensure a safe connection with the tunnel. This not only gave me a sample of the material, but ensured that I knew where it had come from. Plus it was a pretty conclusive sign of agreement with my proposal. It probably wouldn't be going so far out of its way to provide me with a sample if it didn't want me to make the tunnel.

Still, it had been fairly terrifying to watch. Especially when the alien had dropped the piece, and had almost thrown itself off the hull to grab it. I had to remind myself that these were clearly intelligent aliens, and it probably would not be doing this if it weren't certain it was safe. Or at least relatively safe. We were in an alien star system, just being here was pretty unsafe.

The important thing was that neither the alien nor its sample were lost, and it had thrown the sample over for my hull robot to catch. On a whim I made the robot copy the alien's waving gesture after catching the sample, and to my delight the alien had repeated it back to me. I probably would have happily done that for hours if the alien hadn't returned to its ship at that point.

The sample had been useful, anyway. It was mostly aluminium, with some kind of soft material on the back. That was interesting. Aluminium wasn't one of the stronger metals, and wouldn't be my first choice for containing atmospheric pressure while withstanding interstellar travel. Even our xenonite ship had taken some damage during the journey.

I spent a while wondering about the implications of that. Aluminium wasn't as strong as many other materials, nor was it a very good insulator. It was very lightweight though. Maybe their gravity was strong enough that they needed less mass to reach escape velocity? Or maybe they're atmosphere was so thin that they didn't need a very strong material to contain it? Or maybe there was some secret property of aluminium that I didn't understand.

Well, hopefully I'd have a chance to ask the aliens about their ship soon. And I did really, really want to do that. First I had to deal with this tunnel business.

I was incredibly nervous as I made the approach. The plan was simple enough; I had made a tunnel that would connect my ship to the aliens' ship. It was a little under 7 metres long, made of rectangular xenonite panels. One end was carefully curved to exactly match the shape of the alien ship, and the other was already attached over my airlock. My airlock had been designed to dock with the space elevator back on Erid, and I had designed my end of the tunnel to fit onto those mechanisms. Presumably the alien ship had an equivalent system, but since I didn't know anything about it I was going to use a simpler method to attach their end.

Finally the ships were close enough for me to move to the second stage of the process. This part was going to be delicate. I began to extend the five arms of the hull robot towards the ship. I was using the control panel for this, since I didn't actually need to move the hands for this part, and I couldn't control all five at once anyway. The plan was very simple; Each hand held a handle, attached to a flat plate coated in adhesive. Once attached to the ship, I would be able to use them to pull it close enough to meet the end of the tunnel, which was also coated in adhesive.

Very simple, but also there was a lot of room for things to go horribly wrong. As I said, aluminium is not a strong metal. The alien had managed to chisel a piece off of it by hand. If I pulled too hard, or too far, my xenonite tunnel would rip through it like wet dirt. Needless to say I was being very, very careful.

Three of the arms, which were extended slightly further than the other two, made contact with the hull. And suddenly it was there. The sensation was so shocking I almost flinched, which would have been a terrible thing to do while committed to such a delicate process.

Obviously the ship had been there the entire time. I had been watching it through the tactile readout displays, had calculated its size and distance, and modeled it in xenonite. I knew it was there. But I'd never actually been able to sense the ship, only hear the facsimile of it created by the readouts. Now, with this point of contact, I could hear it. Not very well, it was a small point of contact attached by long thin arms. But it was there. In all the excitement it hadn't occurred to me what this moment would feel like. It was a little overwhelming. I wondered if the aliens felt like this. Were they as awestruck as I was? Or was this not as exciting for them?

I shook the thoughts away. I needed to concentrate on the task at hand. The next two arms made contact with their handles, and I waited a moment for the adhesive to set. Then I began very, very gently pulling the aliens' ship towards mine. Through the arms I could hear the groaning of the metal as the ship was pulled along in a way it certainly wasn't designed for. It was an unnerving sound, especially since I knew that if I messed this up I could be endangering the lives of everyone on board the ship. But I had faith in my calculations, and faith in the work I had done. Thanks to the sample I knew the approximate strength of the hull, and with the arms touching the ship I had a sense of how hard I was pulling. As long as I moved slowly and carefully it was going to be fine.

After what felt like an eternity, the end of the tunnel made contact with the alien ship. Now I could hear it very clearly. It was almost unsettling to have a whole structure suddenly come into existence this way. But it wasn't enough to stop my excitement. In the airlock just beyond the tunnel I could hear the alien waiting. It was in the same life support vessel it had been wearing before. That was a sensible precaution; If I had made a serious mistake they would be immediately killed by pressure loss in the ship.

As quickly as I possibly could I flew down the corridor to the laboratory, catching myself on the airlock door. I pulled some levers that I had set up earlier, and my half of the tunnel began pressurising with ammonia. Technically I cold have just opened the airlock door and let my atmosphere fill that way, but there was a massive pressure difference between my door and the tunnel. Doing that would have forced the door open so quickly it would have been in danger of hitting the tunnel and potentially causing damage. Safer to equalise the pressure before opening a large door with a lot of mass.

In moments it had reached a full atmosphere, and the tunnel was ready for me to enter. But suddenly I wasn't sure if I was ready for me to enter. It was, admittedly, at terrible time to be second guessing what I was doing. Was this crazy? Was I going to mess this up? How was I even supposed to begin trying to communicate with these beings? In the room beyond the aliens' airlock I could hear the figure coming right up to the door, and just floating there for a moment. Then it opened its inner door and stepped into the tunnel. It, at least, was not lacking in bravery.

I found myself thinking of Voyager. Long before it had been involved in space programmes Voyager had piloted submersible vehicles to explore the ocean floors. It had had a deep fascination for the unknown, and for life that existed in unthinkable places. It had been one of the very first volunteers for this mission. Despite the terrible circumstances that had necessitated it, it had been overjoyed at the idea of travelling to a distant star.

It would have loved knowing that there were aliens daring enough to leave their own spaceship. It probably would have wanted me to design a way for it to do the same. It certainly wouldn't be hesitating to open the door and greet this new species.

Just for a moment, I imagined that I could borrow a little bit of its courage, and I pulled open the airlock door.

Chapter Text

I was almost shaking with nerves as I floated into the tunnel, grabbing onto a handhold to steady myself. The tunnel was divided into two halves, separated by a wall made of a variety of xenonite panels. I wanted to establish communications with the aliens, and even possibly pass items between us, but first I needed more information. What was the aliens' comfortable temperature range? What was their atmospheric pressure, and what gases did they need? What material would conduct sound most effectively for them?

The tunnel was designed to give me as many of those answers as possible. The wall would not only allow us to separate our environments, but the variety of xenonite compounds would let the aliens indicate whatever material was best for them. And once they pressurised their end, I would learn what conditions their life support was maintaining. Then they could leave, and I could make whatever adjustments they needed for comfort.

The aliens' outer airlock door swung open. They must have depressurised the airlock, because there was no sound of air moving into the tunnel, and the door opened in a controlled way. I tried not to fidget as the figure inside paused, then turned a valve inside the airlock. Now I heard the air rushing in, filling its side. It was a little surreal, knowing there was only about a centimetre of xenonite separating me from an alien atmosphere.

We both paused as it finished pressurising. The adhesive had held, and the xenonite had not reacted to the gas. Not that that was likely to happen, but it was good to know. I wondered what the aliens thought of me. I had heard it before, on my readouts when it was outside the ship, but none of their crew had had an opportunity to observe me yet. Was I strange to them? Were they interested in my anatomy? I fidgeted, feeling a little self-conscious. I was currently acting as their sole specimen for my entire species. That was not a very comfortable realisation.

That thought was completely chased out of my mind a moment later however, when the alien began to remove its life support vessel.

My first thought was that this process vaguely resembled hatching. The back of the suit, or at least the part that had been facing away from me through this process, opened up and allowed the alien to emerge from it. My second thought was that it was so, so squishy. It was disgustingly, organically squishy. I don't know what I had expected, but I really wasn't prepared for that.

Eridians have organic parts, of course. We are alive, after all. But in our entire bodies there is only a few kilograms of organic matter, and it is all safely contained inside the carapace. The only times they're ever exposed are when we're eating, or if something has gone badly, terribly wrong. This alien sounded like it had been inverted, which was a deeply upsetting thought.

The outer layer seemed to be damp, too. There was some kind of moisture- water maybe?- escaping through its soft tissue, which was disgusting. And also kind of alarming. But the alien wasn't having any particular kind of reaction to it happening, and no one else came into the airlock to assist it. The thought that this might be a normal occurrence was also upsetting.

These were not good thoughts to be having when meeting the first intelligent alien species in my planet's history. I shook myself very slightly, chastising myself for being so squeamish. Of course their biology was going to be radically different to mine, we evolved on different planets. There was no need to be childish about it.

The alien moved further into the tunnel, pushing the life support vessel back towards the airlock, and I made myself listen to it more closely. It was the first clear listen I'd ever had of it, and I wanted to make sure I remembered every detail, even if they unsettled me. Its shape vaguely resembled that of the vessel; Four arms, and something protruding from the top, which was not nearly as spherical as it had been on the vessel. The top of the protrusion was covered in something soft and fuzzy.

The alien was oriented vertically from my perspective, and was easily three times my height, taking up more more space in its side of the tunnel. It was wearing some kind of cloth which covered most of its body, except for two of its hand and the protrusion. The two exposed hands had five fingers on them. Interestingly it sounded like the other hands had five fingers as well, but they were shaped completely differently.

It came right up to the wall, but stopped short of touching it. It was moving the protrusion around, and I really needed to think of something better to call it than "the protrusion". I realised uncomfortably that I was going to have to be the one that named the features of this alien anatomy. That was not something I was prepared for, and I pushed it out of my mind for the time being. I raised a hand nervously and waved to the alien, expecting it to wave back like it had before.

But the alien didn't react at all. That was strange, it had waved to the hull robot. Was it different now that we were close together? Was this a social behaviour that I didn't understand? Or could it not hear me? That seemed unlikely, I had used a very broad range of material for the wall, at least one of them ought to conduct sound well enough for them to hear. What was I even going to do if it couldn't hear me?

I watched the alien for a moment longer. The protrusion- I decided to call it a "head"¹ for the time being- the head had several structures on it. There was a round kind of flap in the middle on each side, a vaguely triangular point in the middle on the front, and two gelatinous orbs on either side of the triangle. There was also a crease, which ran horizontally underneath the triangle.

When it had been in the vessel, it had followed the motion of the capsule with the smooth plate on the front of the sphere. That would have been right in front of all the structures on its head, assuming it always wore it the same way around. Maybe they were important for sensory input? But it wasn't pointing any of it at me right now, so maybe it hadn't noticed me? How narrow was its focus, exactly?

Well, I could be here all cycle worrying about it, or I could try and get its attention. So I reached toward the wall and knocked on it three times. Now there was a reaction. For a moment its whole body tensed at the sound, before it balled one of its own hands into a fist and copied my knock. Sort of. Its knock was faster than mine, but it was three knocks again. So it could hear me, or at least my knocking. It still didn't point its head in my direction though. Maybe I was wrong about how it works. Or maybe it just couldn't hear me unless I made a lot of noise.

The alien moved again. This time it held up its hand so that all but one of the fingers was curled in, with the last pointing "up". Then it used the same finger to point back at its own airlock, and began moving in that direction before I could repeat the gesture. I tensed as it turned away, I wasn't ready for it to leave yet. There was still so much information I needed. I hadn't even figured out if it could hear me properly yet. Why couldn't it stay just a little longer?

Actually, that was a really good question. As the alien pulled open the door and moved further into its own ship, I realised that there was no one else waiting in the room beyond the airlock. I'd been too focused on the alien to really notice before, but the absence seemed glaringly obvious now. Surely its crew would have wanted to be nearby. If not to help in case of emergency, then at least to witness the first interaction with an alien species. My crew would have been huddled by the tunnel, listening intently to whatever happened. They would have had to restrain Mycelium from bursting in.

A terrible thought was creeping up on me. I tapped against the tunnel wall urgently, trying to listen to more of the alien ship. The alien had moved into an adjacent room, and was rummaging through some storage compartments. There was no one else in that room either. Or the room beyond that. I tapped more aggressively, listening carefully to every nook and cranny. This was very rude, and more than a little invasive, but I was desperate to be proven wrong.

But no matter how hard I listened, I couldn't hear a single other living thing on the ship. Even if they weren't touching any surfaces, I should be able to hear something. There was only one conclusion I could come to, and it was one I really didn't like.

I was still struggling with this revelation when the alien re-entered the airlock. It busied itself attaching something to the wall, but I wasn't paying much attention to whatever it was. Did they send it here alone? It was a much smaller ship than mine, were they that confident in its abilities? Would they have sent it into space with no one to assist it, no one to watch over it?

Or was it like me? The only survivor of a larger mission?

In my distraction I almost didn't notice the alien turning to leave again. It sent an unexpected wave of panic through me. It couldn't just leave, I hadn't figured out how to talk to it yet. Or what kind of material it needed for the wall. Or why anyone traveling to this system seemed destined to arrive alone. I lurched toward the divider, with no idea what I was planning to do, and that finally seemed to catch its attention.

It turned sharply back towards the wall, turning its head around to each sample. One seemed to attract its attention, on the left side, close to the wall. It floated closer, bringing its head very close to the panel.

"hoʊli kaʊ!"

Oh, well that was startling. And vaguely horrifying. That crease on the front of its head opened, revealing the wet, fleshy innards. Awful. Just awful. But it had made a sound with it! It wasn't like Eridian speech. It seemed to be produced somewhere just below the head, and shaped by the opening. Was that how they talked? I really hoped not, because that was going to take some getting used to. People aren't supposed to just open like that, not in public at least. It was just... no.

It took one of the devices it had stuck to the wall and held it near the panel. I should have paid more attention when it was handling them before, I had no idea what it was for. Maybe it was testing the material? I placed a finger against the panel, trying to ask if this was the one it wanted. Instead of responding the alien pressed its head against the panel. I guess it wanted to hear really, really clearly. Was the head the only part that processed sound? That seemed incredibly inefficient. It must work for them though, or they wouldn't have evolved into a species that could make spaceships.

With it pressed so close I was getting a disturbingly clear idea of the structure of its body. Fleshy exterior, with some hard structures on the inside, and squelching, pulsing organs. There was a sort of rigid but flexible material in places on the head, in the triangular structure and the flaps on the sides. Its midsection was regularly inflating and deflating, drawing air in and out through the triangle. That must be for breathing, I guess. The orbs in its head were moving around too, making constant jerky motions this way and that. I was really not enjoying this experience, but I made myself pay attention. Sometimes it was necessary to suffer for science.

I tapped the hexagon three times, hoping to prompt a response. The alien lifted one of its own fleshy digits, and mimicked me. Four of the five fingers on its hand had three knuckles, with the other only having two. It was also significantly lower down than the other fingers, and oriented a little differently. It was strange to see a structure that was so familiar, and yet so radically different from what I knew. My hands had evolved to grapple prey, and to pry open their tough exteriors. Then they had continued to develop as my people had learnt to use tools, to build and create. I wished I could ask the alien what had shaped its hands.

But it seemed like it had finally heard me, and had indicated a preference. That was a good start. Luckily I had come prepared for the next instruction. From my tool belt I pulled out my little model of the alien life support vessel, and its ship. I didn't have a model of the actual alien, since I had only just heard it. I held out the first model, so that it could see it was its ship, and then used the little doll to demonstrate it going back into its ship. Now that I had more information I needed to modify the tunnel, and I couldn't do that with it still in here.

The alien responded with a new hand gesture. It curled in its fingers again, this time leaving the short, two-knuckled one pointing upwards. I curled up two of the fingers on one of my hands, and pointed the last one up. It was a poor approximation of what the alien was doing, but I hoped it understood.

It turned away from the wall, and I felt another pang. That was just silly, I was the one who had told it to leave. But somehow it still hurt to watch it move away, back into its own ship. I gave myself a small shake. It was just leaving while I reconfigured the tunnel. It would be back, and then we could work on having a real conversation.

The alien waited by its airlock while I reconfigured the tunnel. Or, more accurately, as I used the hull robot which was currently in the airlock to reconfigure the tunnel. It was probably listening to what was going on. Any process, even a mundane one, is pretty exciting when an alien is doing it with an alien robot. I knew this, because everything that the alien did was very exciting to me.

Like these device it had stuck to the wall. I hadn't paid much attention to them at the time, but I had the robot retrieve them for examination. Each device was round, with a flat face on either side like a very short cylinder. One side was slightly convex, and was made of a smoother material. There were electronic components inside, encased in the hard shell. I just couldn't figure out what they were for. Although I had figured out that I could squeeze the flat faces together, and it would make a clicking noise. Click click click.

Click click.

After a few minutes I remembered that I was the middle of a job, and I dearly hoped that the aliens hadn't heard that.

I also designed and built a few new models for the alien. According to my readings its atmosphere was only 1/29th the pressure that mine was ². But that fact was vastly overshadowed by the fact that it was comprised entirely of oxygen.

I may have had a minor moment of panic when I realised that I had connected my ship to one that was filled with a highly flammable gas for some reason. But it was fine. This was fine. There wasn't any cross contamination, our atmospheres were separated by xenonite, so it wasn't like the oxygen was getting on my ship. It still made me very nervous though.

The oxygen must be incredibly important to the aliens, biologically. I couldn't imagine that any sane individual would choose to fill their spaceship with it if it wasn't a non-negotiable necessity. Before we left Erid, I had imagined that a fire was the worst possible thing that could happen on a spaceship, but it wasn't something I'd had to worry about. Fire can't burn without oxygen, and we had sensibly not included any on the ship.

It made me wonder just how desperate they must have been when they built it. It had been difficult enough for us, launching an untested vessel running on an untested fuel source to an entirely different star system. To do all that in a vessel filled with oxygen? Where a single stray spark in the wrong place might cause an explosion? It made me want to shudder with horror.

That terrifying revelation aside, I was putting together a small model to show the alien the difference in our atmosphere. I made two hollow balls, each with a carving of our respective ships on the outside. Inside the ball with the alien ship carving was a model of a single O2 molecule. Inside mine was 29 Ammonia molecules. I was working under the assumption that the alien was familiar enough with chemistry to recognise the atoms. It seemed like a safe assumption, considering its species were advanced enough for space travel.

I was also working on temperature control for the tunnel. The alien's atmosphere was cold. Like, almost cold enough to freeze water cold. According to my readings its life support was maintaining the temperature at around 20°C. Just the heat emanating from my side of the tunnel must have shifted the temperature considerably by comparison. I wasn't sure what the alien's range of tolerance was, but I wanted to keep it as comfortable as possible. That wasn't too difficult though. It's life support was already trying to create optimal conditions, I just needed to make sure the heat from my side wasn't interfering with it.

I was enjoying this.

That thought had made me completely stop what I was doing so I could process it. This work was engaging, maybe even fun. I enjoyed thinking about ways to communicate, building models, designing structures and theorising about how alien technology worked. I hadn't known I still knew how to do that.

Engineering had always been one of the great loves of my life. I had been building since I was small, and I had wanted to do it for the rest of my life. Then for a long time it had seemed like the only thing I would do for the rest of my life. I had believed that the experience had poisoned engineering for me forever. Now I was awestruck to discover how easy it was to love it again, like I'd never forgotten how.

But there was no time for paradigm shifting realisations of the self. I had an appointment with an alien. The alien had used some kind of adhesive strip to attach its clicky device to the wall, so I reused that to secure the atmosphere models on its side of the tunnel. Once they were in place I installed the new wall, made entirely from the material the alien had selected. The width had been adjusted to ensure minimal heat transfer from my side of the tunnel. Hopefully that wouldn't interfere with its hearing.

The alien was still hovering by its airlock door when I finished. I wondered if it had difficulty hearing from further away, or if it simply preferred being close by. My side of the tunnel was already pressurised, so I entered and knocked on the wall three times, since that seemed to be the best way to get its attention.

But instead of opening its door to meet me, the alien pushed away from the airlock, back into the adjacent room it had used before. Alright then. I hung there awkwardly, holding onto two handholds for stability. I hadn't included handholds on the alien's side because I wasn't sure what would be comfortable for it to use. There was no sense including an accessibility feature that might be unhelpful, or worse, actively hinder it in some way. Besides from what I could hear there weren't any handholds on its side of the ship, except in some of the crossing points between rooms.

Thankfully I wasn't left waiting for long. The alien retrieved yet another of the round device before heading back and repressurising the airlock and tunnel. Interesting. Were they important for something? Maybe I shouldn't have taken the ones it left on the wall.

Finally the alien opened its airlock, and I felt another sudden case of nerves. It was fine, I assured myself. The alien was clearly friendly. And it was showing me a tremendous amount of trust, letting me interact with its ship to make this tunnel. It hadn't even used its life support vessel this time. The least I could do in return was to power through some nervousness.

The alien entered the tunnel, and immediately its head turned to point directly at me. I almost trilled with excitement. The wall was a success! Then I was quickly confused as the alien's entire body tensed up, and it turned around as if to leave. Then it seemed to change its mind again and turned back towards me.

I wasn't sure what to make of any of that, so I raised a free hand and tried again to wave to the alien. And this time it finally waved back to me! I just barely refrained from squeaking. We were being professional, I told myself. No squeaking in front of the alien. Instead I waved again, and this time the alien shook its head from side to side. I tried to copy that too, but I had to rotate my whole body to do it since I didn't have any parts that articulated that way.

The alien didn't respond, so I decided we were probably done with gestures time. And it didn't seem to have noticed the models I had left on the wall. Maybe it really did just have an extremely narrow field of focus. I tapped on the wall, this time pointing in the direction of the gifts. It turned its head to follow my finger- it's good to know that pointing means something to it, many animals do not have a concept of pointing- and seemed to notice the models.

"ɔlˈraɪt lɛts si wɑt ju lɛft mi"

Oh, good. It was making the flesh noises again. I chastised myself for thinking that; This was probably perfectly natural behaviour for its species. Its not its fault that it evolved to be so squishy. Maybe it thinks carapaces are gross.

"I'm sure you're a completely normal specimen for your people." I assured it. Then wondered why I would say something like that.

The alien's head turned sharply around to face me again, the hole in its face just hanging open for a moment. I managed not to startle back at the sudden motion.

"ju hæv ə ˈlæŋɡwəʤ haʊ du ju hæv ə ˈlæŋɡwəʤ ju doʊnt hæv ə maʊθ"

It was a little louder than before, I thought it was a little higher pitched. What did that mean? Was it excited? Upset? It seemed to react to me speaking, but it couldn't have understood what I said. Right?

"Sorry?" I said, just in case. It occurred to me that I hadn't actually spoken in front of the alien before. That hadn't been a conscious choice or anything, I just hadn't thought to say anything during that first brief meeting. Not that it would have understood me, even if I had. The alien was still pointing its head at me, and I was feeling very uncomfortable. I pointed at the models again. "Look, there."

"raɪt raɪt"To my relief it went back to inspecting the spheres. Discomfort aside, it really was fascinating to watch it move around. The alien had a definite front and back, and I was certain at this point that its head was providing sensory input. It always pointed it in the direction of what it was paying the most attention to.

I thought about that while it got the spheres open. The fleshy meat exterior was probably not ideal for transmitting sound to the nervous system. It was too soft, it would absorb all the vibrations. So where was it getting sound input from? When it had pressed its head to the wall I had heard quite a bit of its insides. The flesh that was lying over the head was much thinner than it was in most of body, particularly on the top just under all the fuzz. Maybe that was the only point where the flesh was thin enough to allow the sound through.

The alien, having cracked open the spheres and removed the atomic models, said something quietly and tapped its own head with its fist. I absent mindedly copied the gesture while I kept pondering. Even the thinner flesh would dampen the sound quite a lot. I knew the alien was getting enough information to understand its environment, even if it was in limited ways. And why was its attention so directional?

The only theory I could think of was that the gelatinous orbs on the front of its head were involved somehow. Vibrations would travel through them better than they would through flesh, although it still wouldn't be a very clean translation. I wished the biologists were here, they'd probably have much better ideas about this. Something inside me squeezed painfully.

Thankfully the alien distracted me at that moment by exclaiming loudly: "ˈmɑləˌkjulz ðiz ɑr ˈmɑləˌkjulz jʊr ˈtraɪɪŋ tu tɛl mi ˈsʌmθɪŋ əˈbaʊt ˈkɛməstri" It held up the O2 model towards me as it spoke.

"Oxygen." I said, helpfully. The alien pulled the model back to itself, holding it closer to its head. It touched one proton bead at a time, muttering to itself. Maybe it was counting. I hoped that meant it understood what it was.

Whatever meaning it was taking from them it seemed enthusiastic about it. Yes, it was probably bad practice to make assumptions about its mood based on my understanding of Eridian emotions. But it was difficult not to project familiar feelings onto it as it talked, occasionally gesturing emphatically. After a few minutes of this the alien held up one finger like it had earlier, the first time it had left the tunnel to fetch something. I copied the gesture, and the alien left again, heading towards the adjacent room. I guess that gesture meant "Wait while I get something". Or something to that effect. It returned with a larger circle this time.

This new device had a hard, flat material covering the front, and a small box attached to the back of it that made a regular ticking sound. If I listened closely I could hear a simple gear system inside the box. It rotated something at the front of the clock with each tick, but it was behind the cover so it was difficult to hear clearly. The alien adjusted a dial at the back, which made the thing at the front move faster, and I could hear that it was three thin lines, of varying lengths and thicknesses. I followed its circular motion with one of my fingers, to indicate that I could hear what was happening.

The alien moved the hands again, and then took out a stick and rubbed the tip of it on the device, as if indicating an acute angle. I didn't think it was indicating the current position of lines, which I was pretty sure were all pointing up. What was the signficance of this? I took a moment to consider it. It was a circle, with lines attached to gears at the back of it. The gears moved at a regular rate, and each gear movement moved ones of the lines in a six degree arc. For each full rotation of that line another line would move in its own six degree arc, and-

The realisation struck me suddenly. It's a mechanism moving at a regular rate, with lines to indicate how much it had moved, and therefore how much time had passed. It was a clock! The different lines must indicate different units of time!

"aɪl kʌm bæk wɛn ðə klɑk ˈmæʧəz ðɪs" The alien said. It talked a lot, even though it must know I couldn't understand it. I also still couldn't hear its clock very well. Why had it been designed with the lines enclosed like that? It would be much easier to hear without the cover, and from everything I'd observed so far it didn't seem like its hearing was that good to begin with.

"Bring it here." I said, before remembering that it also could not understand me. So I made a motion with two of my hands, like I was reaching forward to grab the clock, and then pulling it towards me.

"wɑt" It said, not seeming to understand. I tapped on the wall, pointing at the clock, and made the gesture again. This time it seemed to get it, and moved the clock a little closer. Progress! I repeated the gesture, and then again, until it pressed the clock right against the wall. In this position I could hear it much more clearly. I gave the alien a small shake of my hands, to indicate success.

And then the alien let go, and the clock immediately began to drift from the wall as it turned to leave. That wouldn't do. I tapped on the wall again.

"wɑɑɑt"

"It's drifting," I said, pointing to the clock. Seeming to realise the problem, the alien pulled one of its adhesive strips off the walls and ripped it in half. It used the two halves on opposite sides of the clock, sticking it firmly to the dividing wall. I shook my hands again approvingly.

The alien turned to leave again, but I wasn't ready for it to go just yet. I tapped on the wall once more.

"dud," it said, turning back to me, "aɪ ʤʌst wɑnt ə dɑrn næp" I tried to copy the gesture it made before, folding down two fingers on one hand and holding up the middle one. the alien repeated it back to me, which I hoped meant it was going to wait while I fetched something. The alien had given me a sense of what time looked like to it. The fastest hand ticked once every second³. A full circle took sixty seconds. By my maths, the next had turned once every 3,600 seconds, and the next in 43,200.

The next logical step was to present it with one of my clocks, so it can understand how my people measure time. Or at least, the standardised version of it used by most scientists. The alien waited patiently in the airlock while I went out to the lab, and brought back one of the clocks.

My clock was, in my opinion, much easier to read than the alien's one. All the clocks on the ship were identical. It was a simple cylinder, with a row of five square windows cut into the side. Inside the cylinder was a series of gears attached to five six-sided dials, with numbers embossed on each side. The dials rotated, displaying numbers through the windows to show the time. The cylinder was made of a sound insulating material, so that the display numbers would be more obvious.

I held the clock out for the alien to inspect, and it became very interested in it. Maybe too interested. For the next 500 or so seconds it did nothing but watch the clock. That probably doesn't sound like a long time, but when you're standing in a tunnel with nothing to do and the only intelligent life form in the star system is quietly watching a clock tick over, it feels like a very long time. It was holding yet another circular device- these aliens loved circles- which it occasionally turned to while the clock ticked.

I waited. I fidgeted. I briefly considered leaving and doing something else for a bit, but then thought better of it. I didn't know what the alien's culture was like but among my people that would be considered rude. The last thing I wanted to do was offend them only other sentient being within trillions of kilometres of me.

"You're taking a long time." I informed it.

"aɪ noʊ aɪ noʊ" The alien held up a finger again, and I held one up in return to acknowledge. At least we were learning a little about each other's hand gesture, although I wasn't sure how we were going from that to having actual conversations. I bounced around for a while, pushing myself from handhold to handhold. It didn't seem to mind, it just kept watching the clock.

Finally, it clicked something on the smaller device, and looked at it. Then it pulled out the stick again, and began rubbing it on its own arm. I had no idea why, as far as I could tell it didn't do anything in particular. But maybe it reacted with the flesh in some way? Although that wouldn't explain why it used it on the clock. After a minute of this it made a circling motion with it, and that seemed to satisfy whatever it was doing.

The alien unstuck the clock from the dividing wall, and used the stick to indicate lines again. One pointing straight up, on angled about 60° from the first. It made a circling motion around the top of the second line, and then reattached the clock to the wall. It waved at me again, and I waved back to it. And then it left. I didn't stop it this time, although part of me really wanted to.

It didn't end up getting very far, anyway. It had exited the airlock, and was heading back towards the room it had used before when it suddenly just... stopped. That didn't seem like something that was supposed to happen. Worriedly, I tapped on the tunnel wall, hoping to hear more clearly. The alien was just hanging there, suspended in the middle of the room just beyond the airlock, its body curled in on itself.

It was almost like it was sleeping. Except that it was nothing like that. Its body was still moving slightly, the air still passing in and out of it, more deeply now. Although now the air made more of a noise as it passed through, as if it was forcing its way past something. I knocked on the wall again, but the alien didn't react. Non-responsive, like I'd expect from someone sleeping.

I hummed worriedly. I didn't like the way it was just floating in the middle of the room. If it was sleeping it should be secured down somehow, so that it didn't drift around and bump into things. Had it not made it to its sleeping quarters because I'd distracted it? That made me feel guilty, but what could I do about it now? Besides, it was the one that had spent 500 seconds staring at a clock. Why did it do that if it was so close to falling "asleep"?

For a while I just waited there, unsure of what to do. The alien should be relatively safe, it was aboard what appeared to be a functional spaceship with no imminent threats. It wasn't as though a predator was going to find it inert and defenseless. And even if it were in danger, it wasn't as though I could help it. It might only be a few metres away from me but it might as well be on the other side of the star system for all I could interact with it. But still. It was seemingly asleep, and there was no one else here to watch over it.

I listened to the alien breathing. Eridians breathe to draw cool air over their radiators, helping to keep the temperature down during waking cycles. I couldn't imagine overheating being a concern in an environment of 20°C, but it must have a temperature range it was as most comfortable in. Assuming it even breathed for the same reason Eridians did. I still knew basically nothing about how its body worked.

I was still not the right person for this. The others could have learnt much more about it by now, would probably have understood far more than I did from the same observations. They'd already have theories about what the shape of its body implied about its evolution, and how it was perceiving the world around it. Not that they would have needed to be in this system long enough to meet the alien in the first place.

But it didn't matter, because I was the one that was here. Me and this alien. And I really needed to think of something to call it other than "the alien". A new species needed a name. Its species probably already had a name for itself, but I didn't think I could recreate any of the noises it made for speech. I needed to think of a word in my language for it.

Ayda had been especially interested in species classification. It could talk for hours about categories and evolutionary lines. From its talks I knew that new species were normally named for distinctive anatomical features or behaviours. That seemed as good a system as any. I could call them Squishies. No, I couldn't do that. If I made it home I was going to have to justify my naming choices to our scientists. I should name them something more dignified. Like Flesh-Clothed.

No actually, that was disgusting.

They weren't rotationally symmetrical like Eridians. They had a front and a back, and the left side was roughly symmetrical to the right side. On the exterior, anyway. Their lower hands were distinctly different to their upper hands. Their upper hands more closely resembled Eridian hands, but were softer and had more fingers. None of which seemed like a good feature to name them after.

I focused on the alien again, breathing softly in its sleep. Occasionally its body would shift around a little, without it seeming to rouse. It was really strange to listen to. It was like it was half asleep somehow, unresponsive but not entirely shut down. Well, I could hardly hope for a more distinctive feature to name it for.

Alright new alien associate, I thought. I name your people Humans⁴.

Chapter Text

If I understood its message correctly, the Human was trying to let me know when it would return. Some brief maths told me that the clock lines would match the angle it had indicated with the stick 7,200 seconds after the start time.

I was pondering this while I made further modifications to the tunnel. It had taken some time to convince myself to step away, but I would be done before the two hours had passed, and I could still hear the Human from where I was working. What made me curious was how it could be sure it would be awake by then. Were Human sleep cycles that regular? Or was the upper range of their cycle just very short, so it knew it would be no longer than that? It was incredible how quickly my list of questions about the Human was expanding, even while it slept.

But until we learnt to understand each other it would be difficult to answer many of those questions. Instead, I focused on the task at hand. We couldn't talk yet, but we could still exchange physical items. The few models I had made had already showed their value in communication. But I didn't want to dismantle the tunnel every time I wanted to give the Human something, so we needed a way to pass things between our environments. Luckily there was a very straightforward solution to this problem: An airlock.

I built a box into the wall that was about 30cm³, and stuck out into the Human's side of the tunnel. There was a door with controls on each side of it, and a pipe that would pump air in and out. It was designed to pull air directly from whichever side of the tunnel it was opening into, which ensured that the pressure would be equal to the atmosphere on that side. I had also mounted my clock onto one of the lattice polls on my side, with the display facing the tunnel wall to make it easier to hear. I didn't know if the Human needed or wanted to hear my clock, but it had left its clock on the wall for me so I wanted to return the gesture.

It was as I was testing the pipe system for a third time that an alarm went off. Not an alarm on my ship, but on the Human's.

My first instinct was to panic. The Human was still asleep, and alone on a ship with an alarm going off. Had something broken? Was it because of something I had done? Maybe I had caused damage to the ship while attaching the tunnel after all. I couldn't hear anything obviously wrong but it wasn't like I actually knew anything about its technology. The Human was completely helpless right now, and there was no way for me to get over there-

The Human began moving, cutting off my spiraling thoughts. It uncurled itself slowly from its ball and muttered something, and the alarm cut off abruptly. Relief flooded through me. Along with more questions. It had seemed like the alarm had pulled the Human out of its sleep cycle somehow. Could that be right?

I had already speculated that the Human wasn't fully asleep, so did it somehow retain its ability to hear? Or was I projecting a cause and effect onto the situation? There was no way for me to know, and I was still calming down from my sudden panic so maybe it wasn't the best time to theorise. But the Human didn't seem to bother investigating the cause of the alarm, which would have been the first thing I did. Instead it made its way back to the airlock, moving a little more sluggishly than it had before.

It noticed the new addition as soon as it entered the tunnel. After spending a moment inspecting it, it perked up.

"ɪts ən ˈɛrˌlɔk" It said, "ju meɪd ən ˈɛrˌlɔk ɪn ˈaʊər ˈɛrˌlɔk ˈtʌnəl" It's raised its upper hands and shook them slightly. I just barely contained another squeak of excitement. I had taught it that! And it seemed that it approved of the new airlock. I copied the gesture back to it, while trying to keep a handle on my enthusiasm.

It held up a finger again, and after I returned it it darted out of the tunnel and back to the adjacent room to fetch yet another round device. Well, to be fair this one was only partly round. It had one flat edge, and there was a metal tab sticking out on one corner. The Human took hold of the tab and pulled, revealing a rattling strip that unspooled from within. Then it let go, and it retracted back into its casing. That was interesting.

The Human pointed to my airlock. I took that to mean that it wanted to know if it was alright to use, and shook my hands in confirmation. It opened the door on its side, placed its new device within so that it floated roughly in the centre, and closed it. On my side, I pulled a lever to adjust the atmosphere within. The oxygen wtihin was rapidly pulled out and the box began to repressurise with ammonia. The new device rattled around inside as the movement of the air shifted it.

It also began deforming. Well, part of it did. There were pads on the flat side that were made of a softer material than the rest of it, and as it was exposed to the temperature of my atmosphere the softer material completely melted, forming a globule that clung to the device. I really needed to find a way to relay the temperature of my atmosphere to the Human so that it would stop sending me things that would melt.

I opened the door anyway, carefully taking the device by the non-melting parts and poked at the globule. It clung harmlessly to my finger, held together by surface tension. When I shook it off it floated over to the wall and stuck there. It was pretty sticky, whatever it was. I'd have to run an analysis on it later to figure out what was in it. The Human did a weird motion with its arms, where it lifted them up by the top joint and dropped them. I tried to copy the move with my arms, but my joints didn't really accommodate it.

The device itself was pretty unassuming. It was made of metal, and I could hear a spool of something inside it that was attached to the little tab. I grabbed the tab, pulling on it like the Human had, and stretched out the spool a little way before letting go. It retracted rapidly, snapping back into place as it had before. Even though I'd seen the Human do it, the force was still a little startling. Also, kind of satisfying.

I pulled out the tab again; It was made of a semi rigid material, able to roll into a spool but also able to hold itself straight when pulled out. The edges of it were curled in a little, prevent it from bending the other way. This time when I released the tab I let go of the device entirely, and the retraction caused it to spin in place.

Then I did it again. And again. New information about Humans: They make fantastic toys.

I could hear quite a lot of spool on the inside of the spool. It was longer than even the span of the Human's arms would accommodate. I experimented by pulling the tab out as far as my arms could reach, and then releasing it again. The recoil was much stronger this time, and it spun wildly in place before me. The gleeful squeal I let out was not especially dignified, but I was too excited to care very much.

"ˈrɑki joʊ" Right. I wasn't alone here right now. I'd gotten so distracted I'd been paying no attention to the sentient alien life form I was attempting to establish communications with. In fact I'd been so distracted that it had managed to leave and come back without me noticing, as evidenced by the second toy it was now holding.

It pulled out the tab a short distance, and pointed to the strip. "lʊk hir si ðiz" It seemed like it was trying to communicate something about the strip to me, although I had no idea what. I pulled the tab out to about the same distance, and it pointed at it again.

"lʊk wʌn ˈsɛntəˌmitər ðɪs laɪn hir" It tapped on the strip, producing a rattling sound as it wobbled. I repeated the action, tapping on it with the same rhythm. It was a good noise, but not nearly as fun as letting it retract was.

"hir ɑr ju blaɪnd" The Human stopped tapping suddenly. "weɪt ɑr ju blaɪnd" I tapped a few times more, but it seemed that the Human was done with that part of the demonstration. It floated there for a minute, watching me. "saʊnd du ju si wɪð saʊnd". It didn't seem like it wanted me to copy it anymore, so I went back to playing with the toy.

The Human excused itself from the tunnel again, but I wasn't paying a lot of attention. I was thinking about how I could utilise the rest of the spool's length. Was the tunnel long enough that I could unspool the whole thing? There was one way to find out.

Pulling out the end, I used the strip to tie a rough knot around a handle near the dividing wall. The material didn't knot very easily, but it would do for my purposes. Then I began climbing back towards the airlock while holding onto the shell. The knot was unstable, so I was moving slowly so it wouldn't pull apart.

"heɪ heɪ". Ah, the Human was back. With a square sheet of metal this time. Was that also a toy somehow?

"What's that?" I asked, before remembering again that the Human didn't understand me. Its bad habits were already rubbing off on me. The Human held up two fingers, so I held up two on an unoccupied hand.

"ˌoʊˈkeɪ wir ɪn ˈmɪmɪk moʊd əˈɡɛn". Now the Human held up one finger, switched to two, then one again, then three. I had no idea where it was going with this, but I copied the sequence. Then it held up the sheet of metal in front of its hand, before doing a sequence of two, one, three, and five fingers behind it. If this was a game it was a very simplistic one. I repeated the sequence, bringing in a second hand to do the five fingers at the end.

"waʊ" It said, moving to hold the sheet at its side. There was something very focused about the way it kept it's head pointed at me, not moving it around as it often did. "hjumənz spɛnt ˈθaʊzəndz ʌv jɪrz ˈlɑkɪŋ ʌp æt ðə stɑrz ænd ˈwʌndərɪŋ wɑt wʌz aʊt ðɛr. ju ɡaɪz ˈnɛvər sɔ stɑrz æt ɔl bʌt ju stɪl wɜrkt speɪs ˈtrævəl. wɑt ən əˈmeɪzɪŋ ˈpipəl ju ɪˈrɪdiənz mʌst bi. ˌsaɪənˈtɪfɪk ˈʤinjəsɪz."

It was the longest thing the Human had ever said to me. Even though I had no idea what it was saying, it felt like this was somehow significant to it. I couldn't have explained why, there was just something different about the way it held itself, a gentleness in the way it spoke that wasn't usually there. Was I projecting? Maybe. But it made me feel an unexpected pang of longing. I wished I could talk to this Human, to contribute to whatever moment it was having right then. I wished I could tell it that I liked its toy, and that I thought I could acclimate to its flesh noises.

In my moment of distraction I must have shifted my weight, or maybe the strip just gave up trying to be a knot, because at that moment it came loose. Now unmoored, the strip with the metal tab at the end recoiled violently, waving recklessly around the tunnel as it did so. Before I had a chance to react it had whipped back towards me, and the metal tab struck me in the hand before fully retracting. For such a small thing it was a surprisingly vicious attack.

I let go of the tape measure, letting it float for a moment while I shook the pain away from my hand. This was apparently the kind of toy that came with an inherent risk. If it was allowed to build too much momentum it could recoil backwards and inflict minor damage. I could only imagine how much it would have hurt if it had been the shell that hit me, and not the small metal tab. Fortunately the pain, while sharp, was short lived.

Next time I would have to tie a more secure knot.

We spent a little longer not getting very much done, before the Human left to work in the room just beyond the airlock. I wasn't entirely sure what it was doing. It was resting on something, similar to a chair¹, using its lower arms to grip onto it while it interacted with some kind of device with its upper arms. Not a circle this time, a sort of rectangle that could open. Inside it were a lot of buttons, that the Human was tapping away at rapidly. I wasn't sure what that accomplished, unless the Human just really enjoyed pressing buttons. Maybe it was some kind of enrichment activity.

I really needed to stop watching it when it left the room, it was impolite. Although it was curious that the Humans hadn't added any kind of sound dampening. As far as I could tell, none of the rooms on the ship were protected against sound traveling through them. Maybe they hadn't thought of it? Or maybe it wasn't desirable, for whatever reason. Whatever the case was they probably hadn't accounted for the possibility of an alien spying on them.

Not that I could hang around listening much longer anyway. As much as I hated to admit it, it was almost time for me to sleep.

It would have been nice to leave the Human some kind of message, but unlike it I didn't have any idea how long I would be out for. There was no way for me to indicate that I would be back "Maybe in two hours, maybe in eight, maybe any time in between". At least not one that I could be sure it would understand. I'd just have to leave, and trust it knew that I would be back.

I re-entered my ship, closing the airlock and pushing myself towards the back where my room was. The room was as I had left it that morning, before I had made contact with the first known sentient alien species in my planet's history. The enormity of it kept hitting me. It was all so impossibly tremendous, I had no idea how I was handling any of it.

I grabbed one of the loops in my sleeping area, before something occurred to me. The fabric pockets were still strapped by the sleeping area, and I dug into the one containing Adrian's rock. It was still damaged, obviously. The crack had carved through Eridani, and part of Planet Three, but it had missed Erid. The missing chunk was broken into several pieces, which I kept carefully stored in my desk so they wouldn't drift around.

If I was very careful, I might have been able to glue the pieces back into place. But Adrian had never liked attaching rocks with glue, it insisted that it ruined the sound of the rock. Besides, Adrian was of the opinion that it was in the nature of art to deteriorate. It was a poignant reminder, it would say, that nothing was forever. No matter how long it seemed to last. But maybe I could ask it to re-carve the missing section for me.

Carefully, I held onto the rock as I hooked my arms into the loops. I ran a finger as lightly as I could across the top of it, feeling the transition from smooth to rough to smooth again. From within my sound dampened room, I couldn't hear the Human anymore, even if I tapped on the wall. But it was out there, maybe still tapping away at its buttons.

I knew there was nothing it could do to help me if something went wrong. Even if it could hear me, which was very unlikely, and if there was a way to get onto my ship through the tunnel, which there wasn't, it would probably be crushed by my atmosphere, and possibly also melt. But even so, knowing that there was a living person somewhere nearby made the sleep that washed over me just a little less frightening.

When I woke up the Human was asleep again. I think. It wasn't floating the middle of the room this time, at least.

It had retreated to the third room of the ship, behind the room it had fetched all the round devices from. In the room were three ovals with soft material inside them. The Human was lying horizontally on one of these, using a blanket to secure it in place. I guessed that must be a Human nest.

It had left me something on its side of the tunnel too. Stuck to the dividing wall was some kind of model made out of flat stick things, which had been snapped and bent to resemble Eridian numbers. I had absolutely no idea what kind of material it was made of, although it obviously wasn't any kind of metal. All this gave me three data points.

1) The Human's wake cycle was somewhat erratic. Between our initial communication, setting up and re-configuring the tunnel, and our first interaction, it seemed unlikely that the Human had been awake for less than 30 hours before it slept the first time, at which point it had slept for two hours. Now after being awake again for only a few hours, it was asleep again.

2) It was very confident in its ability to predict its sleep cycle. This was the second time it had left me a message to let me know when it would return. At least, that's what I assumed it was. The number it had left me had six digits, one more than the clock did, but it seemed like a safe assumption that it was letting me know it was returning some time after the clock finished a full cycle.

A brief calculation told me that the model was indicating a time a little over four hours from now. Longer than the last sleep cycle, even without knowing how long ago it went to sleep. And so soon too. Was this typical for Humans? I felt a brief swell of anxiety, remembering how tired my crew mates had become when they got sick. How they had slept longer and longer every cycle.

I shook the thought away from me. There was no reason to assume that was happening now. I didn't even know if Humans could get sick in the same way. Although there was the third data point to consider. Three nests, and one occupant. Whatever had happened on its way here, the Human had not left its world alone.

Wild speculation wasn't going to get me anywhere except spiraling into uncontrollable anxiety. I had four hours before the Human was scheduled to wake up. That was fine. There was other work to do while I waited. In fact, there was a backlog I really needed to address. The arrival a new ship in the system had somewhat distracted me from my usual chores, and I hadn't even checked the systems in a couple of cycles. I really couldn't afford for the ship to break down now, while it was attached to the Human's ship.

I conducted a thorough systems check, as I had done every cycle for many years. But now as I did it I could hear the Human ship hanging onto mine. Incredibly there were no new issues yet, despite being unattended for longer than usual. Although there was still the existing list to work through. It was all fairly uninteresting busy work, and I had a much harder time focusing on it than usual. I was mostly listening to the clock by my workshop bench, waiting for the time the Human was supposed to return.

Finally I heard the alarm sounding on the Human's ship, and I perked up. It was the same sound that had happened last time, and the Human began moving in response to the sound. Then it said something quietly and the sound stopped. The Human settled down again without rising. Hmm.

I made my way from my workshop back to the tunnel. There was no further indication that the Human was waking as I went, and by the time I arrived it seemed just as asleep as it had been for the last few hours. I fidgeted, bouncing from handhold to handhold. This was the time that the model had indicated. Had the Human made a mistake in its calculations? Or was something wrong?

Images of my crew, sick and exhausted, rose unwillingly to my mind. It wasn't that. It couldn't be that. I wouldn't allow it to be that. Although even as I thought it I was aware how painfully little say I got in the matter. What was I going to do about it? Float in the tunnel and panic some more?

I brought one hand to the dividing wall, curled loosely into a fist. Knocking seemed to get the Human's attention before. Maybe I could pull it from sleep, the way the alarm had before. The way this alarm was probably supposed to. I desperately wanted to make sure that it was okay. I wasn't ready to be alone again. But I forced myself to pull away

An Eridian always sleeps until its body is ready to start again. I didn't know the first thing about Humans or their sleep cycles, but presumably sleep was important to its function. Maybe I could pull it out of sleep, but I didn't know if that would be detrimental to it. If it needed more sleep than it anticipated then I should probably leave it to it.

That sentiment got me through the next two hours of fretting. I abandoned my repair work, which I was too wound up to focus on. Instead I spent a while inventing new games with the Human toy. My favourite one involved tying the end to a handhold, and then pushing myself while holding the shell and seeing how far I got before I was pulled back. I found I could easily get to the end of the spool that way, so I started trying to push the exact right amount to go specific distances. That was a lot more challenging, but it only resulted in minor injury four times.

It was an admirable effort, but the more time that passed the more my anxiety built. Could Humans sleep for too long? It clearly intended to be awake by now, could sleeping longer than it intended harm it? The concept of sleeping the "wrong amount" hadn't existed to me until just now, so I really had no idea what the rules were.

After two hours I found myself back in the tunnel, scuttling up and down the handholds. It was still a bad way to pace. The Human had been asleep for at least five hours, probably more. That was more than double the amount it had slept previously. That wasn't unreasonable, but it had come very soon after its last sleep cycle. I had no way to know if that was normal. If the Human was in danger I would at least like to know, even if I couldn't do anything about it.

Finally I just couldn't take it anymore. I knocked on the dividing wall, just hoping that doing this wouldn't hurt the Human somehow. No response. I knocked again, trying to ignore the rising panic. This time the Human moved, but remained horizontal. I knocked again, louder, and that finally got a result.

The top half of the Human rose off of the bed. It mumbled and rubbed its head with its hand. It was such a relief that I felt weak for a moment. The Human was awake. That was good. I hoped it was good, anyway. A mechanical arm descended from the ceiling, handing something to the Human. So it did have a robot. Why didn't it use that for the outside of the ship? That would be so much safer than the little vessel it was using.

It was a relief to hear the Human moving around, but it wasn't coming to the tunnel and I felt restless and impatient. I knocked once more, trying to get its attention. The Human said something, and I was startled to hear the sound of another Human voice emanating from the ship. Was that a recording? There definitely weren't any other Humans aboard, I would have heard them. But I hadn't seen the Human activating any devices either.

There wasn't a lot of time to ponder on it, as the Human very suddenly rose from its nest and rushed towards the airlock. Some of the tension eased from my muscles as it finally arrived and opened the door.

" ˈsɑri ˈsɑri" it said, stumbling in. I was glad to hear that it was alive and not in obvious distress- although I wasn't sure what that would sound like- but I was also quite irritated that it had let me worry about it for so long. What was the point of leaving behind a message if you couldn't stick to the schedule? I knocked on the wall again, to make sure I had its attention, pointed to the model it had left behind, and then balled my fist to shake it in admonition.

"aɪm ˈsɑri" The Human interlocked the fingers of its upper hands, clasping them together in a gesture I didn't recognise. I decided to assume in good fairth that this was a way of apologising for its lateness. It hadn't given me any other reason to assume it was usually inconsiderate. Besides, it had been sleeping. And while it seemed like it could still hear to some extent while asleep, I didn't actually know how it worked for it.

The Human held up one finger again, and I reluctantly returned the gesture. Thankfully it didn't go far, just to the room outside the tunnel to grab the device it had been working on before I went to sleep. Except that it had a second, identical device attached to it now. They were both open, stuck to each other by one of the halves so that the halves with all the buttons were sticking out on opposite sides.

It pressed the joined devices to the tunnel wall, securing them in place with more adhesive strips so that it could access both sides by moving around. Then it turned back to the wall and pulled off one of the little number models. It was the one that was shaped approximately like a one.

"wʌn," It said, pointing to the model. "wʌn." It pointed to the opening in its head, and back to the model again, and repeated "wʌn." Then it pointed to me, and waited. Any lingering agitation I had vanished in a moment. It was clear what was happening; The Human was teaching me its word for "One". It was as good a place to start as any, if we were going to teach each other our languages.

I pointed to the figure so it would know what I was communicating. "One," I said.

It wasn't my first time learning a new language. People from all over Erid work in the orbital facilities, and the work is a lot easier if you learn at least some of each other's language. But for every other language I have ever learnt there has always been some kind of baseline. Most of the time I would be learning from someone who also knew some of my language. But even when I've had no language in common with another person we at least had shared concepts. For example, we had objects that both of us would recognise, or similar gestures. We would at the very least have the same body parts that we could use as a foundation. Sometimes there are even a lot of very similar words, if the two languages are closely related.

Exchanging language with the Human was nothing like that. Our languages were not only completely unrelated, but the Human didn't even produce sound in the same way that I did. As I had noticed before the sound was created just below the head, and was shaped by the Human's head opening and the position of a muscle inside it. It could only produce one tone at a time, and although the pitch would rise and fall as it spoke that didn't seem to be related to the meaning of the words. We were starting at the lowest possible baseline, and I was thankful that the Human had determined a good starting point.

We began with numbers, and simple words like "Yes", "No", "Me", and "You". There wasn't really any structure to it, we just started with whatever little words we could, and then used those to build up to other ideas. It was achingly slow to begin with, but the further we got the easier it was to learn more. It probably helped that we were both highly motivated. Or I was, at least, and I thought that the Human was too. It was here making the effort, after all.

We were a little slowed down by the Human's learning process. Every time I said a new word, it had to press buttons on one of the joined devices, then move around to the other side to press buttons on the other one. Even when I was repeating words it had to consult the device. And I still had no idea what it was for. From context I was tempted to assume it was some kind of record keeping device, either for posterity or because it needed help remembering, but I had no idea how that would work. I couldn't hear any moving parts within the device. I couldn't even hear any way for the device to produce sensory output. There was a slight hum to it, which made me think it must be running on electricity. It was a little loud, which suggested that it wasn't running very efficiently. But I didn't know how any of that translated to storing information.

We did make good progress though. We even managed to cover some of the basic scientific units, which were going to be crucial if we wanted to work together. I really hoped that it wanted to work together. After several hours of this the Human retreated to the other room, and did some more button pressing on its device. By the time it returned I was too curious not to try and ask.

I pointed at the devices, which it was sticking onto the wall again, and asked "What is that?" Well, I sort of said that. I had realised early in the process that the Human understood me faster if I used its grammar when I spoke, so in my language the words were all in slightly the wrong order. It seemed to speed things along though.

The Human pointed to the machine. "This is 'kəmˈpjutər'. It..." It took a moment to consider how to describe it. "It is thinking machine." Well that didn't explain anything. How does a machine think?

"Thinking machine?" I asked, hoping for more clarification."

"Yes. Remembers things. Does... thinking." It shook its head, which sort of meant "No" but was also just generally negative. "Hard to explain. Sorry ˈrɑki." I clicked two fingers together to dismiss the apology. It had been too much to hope that it would be able to describe a machine with our limited vocabulary. Now I had more questions that ever about it, but it would have to wait until we had more to say.

At least now I knew I had been at least partly right. The devices were storing information somehow. It must have been storing a reasonable amount too, considering how many words we had already exchanged. It reminded me of my mentor. My mentor was a brilliant engineer, and responsible for designing some of the earliest vehicles to be launched into orbit. It had also had considerable difficulty with recalling information. It was constantly forgetting facts, numbers, appointments, and the locations of various items. One of my duties as it student had been to help it keep track of information, and to take notes that it could review later. I imagined a machine like Grace's could have been invaluable to it.

"Understand," I told the Human, "What was last word?" It had said something after sorry that I hadn't recognised, and I was trying to keep on top of any new vocabulary. The Human hesitated before answering.

"Oh. ˈrɑki is word for you."

"Word for me species?"

"No, species word is ɪˈrɪdiənz. Word for you is ˈrɑki." It clarified. Oh. Apparently the Human had named me. That was interesting, if a little presumptuous. Was that something Humans did? Naming strangers? It didn't seem like a very efficient system for identifying people.

"Understand." I said, which wasn't true but was close enough to what I meant. "Why that word?"

The Human took a moment to consider how to explain. "Need word." It said, "My planet made of soft part and hard part. Need word for hard part" Hard part of planet.... oh! I had a pretty good idea what it meant. I held up one finger, then exited the tunnel and went to my workshop. Adrian's rock was back in its pocket, and I carefully removed it and brought it back to the tunnel. I showed the rock to the Human, who perked up.

"Yes!" It said, "That!"

"This is 'rock'," I told it. It was a sedimentary rock that Adrian had collected from a hill near our home. At some point in the distant past that hill had been part of a mountain range that stretched across a continent, and stood thousands of metres tall. Over the course of hundreds of millions of years the incomprehensible weight of time had ground it down to nothing more than a steady incline of rocky ground. Adrian said that it represented the history of our world. It represented how the mountain had survived, even though it had to become something different. It represented all the love and concern it felt for me, going so far away from home. There wasn't a word I could tell the Human that would encompass all of that. Rock would have to suffice.

That Human pointed to the rock. "That is ˈrɑk," it said, and then pointed to me. "You are ˈrɑki." I took a moment to sound that out in my mind. The name it used for me was a variation of its word for "rock". Apparently Humans also liked to name things for their most distinctive feature. Maybe I should have called it a Squishy.

There was a tap on the glass, and I turned my attention back to the Human. It pointed at me again. "What is... word for you?" I trilled with amusement. This was probably the longest it had ever taken to introduce myself to a new acquaintance.

"Name." I said, "Word for person is 'name'. Name for me is 'Rocky'." The Human gave me its own word for "name", and tapped some more at its computer.

"Does you name mean something? I can call you something... same?" It asked. It wanted to know if there was an equivalent to my name in its language it could use instead of the one it had chosen. I thought about it. One of my parents had given me part of a song as my name. My parent had loved to sing, especially when it was happy. The song was one that its own parent had sung to it as a child, and that it had loved its whole life. It had said it wanted my name to bring people as much joy as I inevitably would. Once again, there was no word I could give the Human yet that would explain that. I dragged my finger lightly across Adrian's rock, feeling the rough surface of the break. Rock would suffice, I thought.

"No." I said, "Name you use is good."

Chapter Text

We carried on like that for some time, slowly expanding our shared vocabulary. Whatever Grace had done with the laptop seemed to have sped up its learning process considerably, so we were moving a bit faster now. It was nice. I'd never been the most social person in the world but it was nice to be talking to another person again. And it was so different from anything else I had been doing for the last 46 years. I could almost feel the disused parts of my brain waking from slumber.

I even learnt the Human's name. It was called Grace. Well, actually it was called Ryland Grace, which was two separate names that was used as one name. But Grace was a noun, which meant I could use an equivalent word for it in my language. To me, its name was just Grace.

After a few more hours of vocabulary building, Grace retreated to the room it sometimes fetched things from and returned with a tube of liquid. "ˈæstrəfeɪʤ" It said. I didn't need it to explain what it was. I felt my whole posture stiffen, my body instinctively moving to a more protective position. Somehow, despite it being the whole reason I was here, I hadn't been ready to confront this conversation.

"Astrophage." I said. I hated how quietly the word came out, like I was afraid of alerting it. Grace entered the information into its "thinking machine". Then it pointed to the tube.

"Astrophage on my star. Bad."

"Astrophage on my star. Bad bad bad." Bad wasn't a strong enough word for what Astrophage was, but I don't think such a word exists. If every person on Erid spent the rest of the lifespan of the universe writing exclusively about Astrophage I don't think we'd ever truly be able to express the horror of discovering it on our star. I only hoped that future Eridians would never have to understand it for themselves.

"You come from where?" I asked Grace.

"Not understand"

"You star is what name?" I was assuming that its star had a name, if only for the purposes of astronomical study. If we were going to work together we were proabbly going to be talking about each other's stars a lot. Besides, if I was going to help to save it I'd like to know what the Humans called it.

"Oh! sɔl. My star is called sɔl."

"Understand. Eridian name for you star is Sol¹."

We traded our names for Eridani as well. I noticed that Grace's word for it was very similar to the word it used for my species. Had it named us after the star? That was a very non-specific way to name a species; There were a lot of other things that lived on Erid, although none of them had representatives in this system.

I really wanted to talk more about this subject. There were a lot of questions I wanted to ask, like "What has your species learnt about the Astrophage?", "How long did it take you to develop your space travel technology to get here?", "Do you have any, and I mean any idea at all what we should do about this?". But we didn't have the vocabulary yet for me to ask any of those questions. At least this seemed to confirm one thing: Grace and I were here for the same reason. I had suspected as much from the first time I heard its ship, but this made me certain. That meant that we were fighting the same fight, and therefore that we could be allies.

Grace checked something on its arm. It was yet another round device, but this one was attached to two straps that fastened together to hold it in place just below Grace's hand. Then it turned to me again.

"Human bodies must slip," it said. That was a fairly abrupt change of conversation, so I assumed this must be important. "slip is this." It curled up into a ball, and began making some very grating sounds with its breathing, which was a little alarming. It quickly uncurled again, and pointed to my clock. "Humans slip for 29,000 seconds."

"Many seconds... why be still so many seconds..." I pondered aloud. The sound it had made had been worrying, but familiar. It only took me a moment to recall the first time I had heard it sleep. It had curled up just beyond the tunnel and made a similar but less exaggerated sound. It was mimicking Human sleep.

"Understand!" I said, and I let my arms go limp and curl up in an imitation of my own sleeping cycle before springing back to life. "Eridians same! Sleep!" 29,000 seconds was a long time though. It was in the middle range of an Eridian sleep cycle, but Grace had only woken about 17 hours ago. It seemed like it was getting much more sleep than a healthy person should.

But then, Grace didn't really seem to properly shut down when it slept. It still moved around, it was still able to respond to external stimuli. It was an incredibly useful skill, but maybe the trade off was that their bodies weren't rested as well as an Eridian's during a typical sleep cycle.

When we knew more words I really needed to ask Grace every question about Human biology I could think of. Biology wasn't something I knew a lot about, but alien biology is pretty fascinating regardless of your usual fields of interest. Plus I had friends back on Erid who would never forgive me if I met an alien and didn't bring back as much information as I could about it.

Grace pushed some more buttons, and then turned to leave the tunnel. "I'm going to sleep now," it said, "I'll be back in 29,000 seconds."

"I observe." The words had left me before I even realised I was going to say them. Not for the first time I reflected on what I poor choice I was for first communication with an alien species.

It's not exactly rude to offer to watch another person sleep. But it is considered something done only among very close friends, family, and paramours. Asking someone to watch you sleep is an extension of trust. Offering the service was incredibly forward. Offering it to a person you met one cycle ago and with whom you could not even have proper conversations yet was... not something a more suitable Eridian would have done.

"You observe?" Grace asked. I didn't yet understand Human body language, but I had to imagine that it was conveying incredulity at the suggestion. I considered that I really ought to apologise for overstepping. Maybe teach Grace some more words so that I could explain that I really wasn't very good with people. That other Eridians would be better at this kind of thing, and that I was sorry it got stuck with me just because I was the only one here. That of course it was ridiculous of me to expect it to want me to watch over it.

The last person I had watched over was our navigator, Ursus. It had hung on longer than everyone else, but it had eventually fallen ill as well. It had needed so much sleep as it got sicker, and it had moved into my workshop so I could work while I watched over it.

"I have to sleep now," it had said, and it was so, so quiet. "I'm sorry I haven't finished my work yet."

"Don't worry about that," I told it, taking its hand and squeezing gently, "You rest, I'll watch. We can continue the work when you've recovered."

"Thank you Rocky. I love you."

I think I already knew it wasn't sleeping. Even if I couldn't admit it, I knew. I watched for six hours, twelve hours, twenty-four, forty-eight. Then it had been almost eighty hours, and I could feel my own waking cycle coming to an end. I couldn't keep watching over Ursus. And there was no one left to watch over me.

"I observe." I told Grace, because we were so very, very far away from anywhere where etiquette mattered. Maybe I was the wrong person for this. But I was the one who was here, and so was Grace.

"I will be still for 29,000 seconds. Many seconds. I will not do anything." Grace warned me.

"I observe." I assured it. "Wait." I bounced back along my ship to the workshop, where I picked up a ship part I had been in the middle of fixing, along with my tool belt. I really was going to have to do something about falling behind on repairs, but there was nothing critically wrong on the ship at the moment. It could wait. For the time being I brought my items back to the tunnel, where Grace was still waiting.

"What is that?" It asked, noticing what I was holding.

"Turbulent oscillator². Turbulent oscillator not function. I change, turbulent oscillator function." I mimed working on the device with one of the tools.

"fɪks" Grace said. "You fɪks."

"Fix," I confirmed, and Grace added the word to its thinking machine. Then it went back to its own ship, and fetched the soft parts of its nest, along with the blanket. It stuck the big soft oval to the wall with a large amount of adhesive strips, and taped down the blanket so that it covered all but one end of it.

"I sleep now." It announced when it was finished.

"Sleep" I confirmed, getting my tools ready to take apart the device.

Grace reached over and clicked the round devices on the wall, which I had yet to determine the purpose of. I really needed to ask about those. With that attended to, it wriggled itself into the space between the soft oval and the blanket, so just its head was sticking out. Then it wedged a soft rectangle between its head and the nesting material.

It didn't take long after that for Grace's breathing to become slower and deeper. It made that grating sound again, but not as loudly as it did when it was demonstrating. I had intended to begin work on the turbulent oscillator, but I found my attention drawn to Grace.

After hours of talking to it and learning its language I still didn't know a tremendous amount about Humans. They had a star infected with Astrophage, like we did. They built a ship to study Tau Ceti, like we did. They, or at least this one, seemed to need a lot of sleep. They're very squishy.

I believed that Grace was also excited to meet an alien species. I believed that it wanted to work with me, to save both of our worlds. Its memory was poorer than most Eridians, but it still had a keen enough mind to keep up with our evolving conversation. I suppose if the Humans hadn't considered it intelligent, they wouldn't have sent it on this mission.

There were still so many question to ask, and not nearly enough words to ask them. I wanted to know everything there was to know about Humans. About this person. I wanted to know who it was. What kind of life it had lived that led it all the way out here. Whether it had been afraid to come, like I had been.

I remembered the last cycle I spent at home. Adrian had been afraid, although it had been trying not to show it. We had sat together, quietly thrumming while we waited for the hour I would need to leave. We hardly said a word to each other the whole time, but there had been no need to. I remembered the way it had held my hand so tightly, like that would keep me from drifting away. I remembered the press of its hand when it gave me the rock the next cycle, and the weight of all that gesture asked of me.

Had Grace sat with anyone before leaving? Was anyone waiting for it back on Earth? Was it also terrified that it wouldn't make it home?

Grace shifted in its sleep. What strange creatures, I thought. What a bizarre and fantastic companion to find, so far away from everything. I finally picked up my tools and turned my attention to my work. My mentor used to say that hope was like a high powered cutting tool. It was necessary for a lot of work, but there was always a risk of slipping and cutting off a finger with it. Many people found they were too afraid to use it again after hurting themselves with it. I was afraid to use it. But I knew I wouldn't get very far without it. And once I had it in hand again, I had found that the weight was still familiar. Only time would tell if I would use it well, or if it would cost me another finger.

Although we hadn't been able to actually talk about biology yet, I still learnt a lot about Humans over the next cycle. Or at least, I learnt a lot about Grace, and I hoped that would extrapolate to most other Humans. Here are some of the observations I made:

1) Grace required constant intake of liquids. It always had some kind of fluid-filled pouch with it that it slowly ingested over the course of our conversations. Apparently it needed a lot more than it could get from its food. Speaking of which:

2) Grace had absolutely no shame about eating in front of me, be it solid or liquid. Either Grace was very strange or this was normal behaviour in its culture. It ate through the same orifice which it used to speak, which I guess made that its mouth? Except that it was really different from an actual mouth. I decided to call it a mouth, to differentiate³ . I suppose if you had to spent all day opening your orifice to communicate you might be less self conscious about opening it to eat. But I tried very hard not to listen when it was happening.

3) Its hearing range was very limited. Grace couldn't seem to hear things that weren't happening in the same room as it, unless they were quite loud. It could hear me tapping on a wall, or speaking if I raised my voice, but not much else. It also couldn't seem to hear most things unless its head was pointed directly at it. My leading theory was that the orbs were involved somehow, but I didn't really have any idea how that worked.

4) Human technology is almost fantastical. The thinking machine stored a tremendous amount of information. Any time Grace was unsure of something it would find the information on the machine. It could also play recorded sounds, and was apparently translating a lot of what I said. I wanted to take one apart so badly, but I wasn't even sure its components would survive in my atmosphere. Plus it seemed rude to ask.

5) As noted previously, despite its memory issues it didn't struggle with comprehension. While it relied heavily on the machine to store information for it, it had no trouble incorporating that information into our discussions. It was also incredibly curious, which is a good quality in a scientist.

6) It really did need to sleep a lot. Before my next sleep cycle it had to complete three more eight-hour sleeps, as well as an occasional shorter one hour sleep. I wasn't sure if there was an appropriate time to ask if that was a normal amount of sleep for its species, or the result of illness. The rate didn't seem to be increasing, and it was lively enough when it was awake. I was still observing closely for any signs of deterioration, although I had no idea what that would sound like for a Human.

At the same time I was learning all of this, I was also having to invent a lot of words for various parts of its anatomy. I was doing my best with it, but it really wasn't something I excelled at. So far I had named:

The Head: Lumpy round protrusion at the top of the Human body.

The Hair⁴: Soft fuzz that covers the top and back of the head. I was uncertain as to the purpose of this feature.

The Face⁵: The front of the head. Includes several structures that serve various functions, such as:

The Nose⁶: Pyramid made of a rigid but flexible material, the primary orifice through which Humans breathe.

The Mouth: Used for talking, as well as eating. Also appeared to be connected to the Human lungs, which facilitates Human speech.

The Legs: The lower arms, which Grace distinguished from its upper arms. It seemed that in an environment with gravity Humans use the legs for walking, and the arms for interacting with objects. They lack the range of motion and flexibility of the upper arms.

The Feet⁷: Hands attached to the lower arms. Not shaped for holding things, mostly used for stability while walking. These were covered most of the time by Grace's clothes.

A lot of this information had been gleaned from observation or from tangential conversations. It really made me want to ask further questions about it all, but I was wary of derailing our conversations. We still hadn't managed to properly talk about the Astrophage problem yet, and I didn't want to do anything that would delay that. I was still taking careful note of everything I learnt though. Our biologists and scholars would probably be thrumming about this subject for decades, and I wanted to remember all I could for them.

I wondered occasionally if Humans and Eridians would ever meet again after this. It seemed strange to think we might not. After all, I knew exactly where Earth was, and Grace knew where Erid was. We both had access to Astrophage, and the technology to harness it for fuel. Theoretically we could build ships to travel to each other's worlds and learn even more.

But I was the only survivor of my mission. 22 Eridians had died on this ship, from causes I still didn't understand. And while I didn't know what had happened to Grace's crew it seemed that there had been three Humans aboard when it left, and only one of them had made it here. Would traveling the stars to meet an alien culture, and explore and alien world, be worth the cost of so many lives?

No. No it wouldn't. But it was still sad to think that I might be the only one of my kind to ever meet a Human. I wasn't worthy of such an honour, or fit to carry such a burden. But all I could do was listen, learn, and try to bring as much back to my people as I could.

We managed to fall into something of a rhythm. Grace's full cycle was about 24 hours long, with 16 waking hours and 8 sleeping hours. Approximately, anyway. It ate solid food just after sleeping, and twice more during its cycle, and ate liquids throughout. I know, it's incredible its species gets anything done when they have to eat and sleep so often.

However it made up for its lack of consciousness with sheer enthusiasm. It spent nearly every waking hour in the tunnel with me, learning my language. I even occasionally heard it playing recordings of my speech on its thinking machines when it was away from the tunnel, apparently practising its memory. At the end of each of its cycles, it would sleep in the tunnel while I watched over it.

We were making very good progress, considered we had only met each other two cycles ago. Grace seemed as determined as I was to begin working together, making special effort to make sure we had a mutual scientific vocabulary. Toward the end of my cycle, it broached the subject of a unit we hadn't covered yet.

"We need to talk about mass." It told me, after returning from a meal.

"Mass, Kilogram⁸," I said. Kilogram was the unit Grace used for mass. Although I had, once again, had to make up a word in my language that meant "word Humans use for mass". If I had known making up words was going to be so important in this part of my life I would have paid more attention to the subject of linguistics. The scholars on Erid were not going to be happy with some of the choices I had made.

"Yes, how do I tell you about a Kilogram?" When Grace wanted to tell me about time, it could show me a clock. When it wanted to tell me about distance, it could use objects of different lengths. But we couldn't show each other weight, because we were in a weightless environment.

Luckily, there are other ways to measure mass, and I had given this particular subject some thought already. I reached under my carapace to my toolbelt, and retrieved a small ball made of iron.

"I know mass of this ball." I told it, "You measure. Tell me how many kilograms ball is. Then I knew Kilogram." Mass is a function of size and density. I know Grace is aware of elements, so if it knew the density of iron it could calculate the mass easily.

"Yes! Give me the ball!" I was beginning to recognise what enthusiasm sounded like in Grace's voice. It was a complicated blend of pitch, volume, and speed that I don't think I could have described to another person. It was kind of instinctive, a feeling I started to develop after so many hours of conversation. I think it was pleased that I had a solution already.

I put the ball in the airlock and cycled it to match Grace's atmosphere. Grace waited a few moments for it to cool before reaching in to take it. It was very mindful of touching things that were too hot, which probably wasn't good for its exposed flesh.

"How will I measure this?" It said quietly, inspecting the ball.

"26" I told it. It had recognised the molecules I had given it during our first meeting, so it must be able to identify elements by their number of protons.

"What about 26?" Or maybe not. I pointed to the ball it was holding, to make the point clearer.

"Ball is 26."

"I understand. Ball is a mass of 26."

"No. Is not."

"It isn't?"

"Is not. Ball is 26"

"I don't understand." Right, okay. I could see where the miscommunication was happening. This would be easier if we had talked more about elements before now. But I could figure this out. The models had helped it before, maybe another one would be useful now.

"Wait." I told it, and headed back into my own ship. Building a model wouldn't take very long. That was good, because it wasn't going to be long before my next sleep. It wasn't quite on me yet, but I could feel it creeping in around the edges.

I made it back to my workshop, and quickly carved out a mould for an iron model. Xenonite started as two liquids that would soldify when combined, so it was easy to shape. I just had to create a mould, fill it, and allow it set for a few moments. Before long I had a model of an iron atom in hand, and was bringing it back to the tunnel.

Apparently that wasn't quite fast enough though, because Grace had wandered off. Point 7 on my list of facts about Humans: They're bad at waiting. A quick listen told me that it was in the adjacent room again, playing around with the ball, some string, and a pouch of liquid. Water, probably, since it consumed the stuff endlessly. Normally I tried not to listen when it was eating, but I was baffled enough by what it was doing that I momentarily forgot my discomfort.

After a moment I realised what it was likely doing. In my absence it had devised a rudimentary means of gauging the weight of the ball, by using the water as a counterweight. How terribly clever. Of course it was a lot less accurate than waiting, like I asked, and calculating the mass of the ball based on density.

I tried not to be irritated, but it was difficult to ignore how close I was to sleeping. I didn't want to fall asleep when it wasn't here. I had spent almost 50 years falling asleep alone, it would be nice to finally have some company again.

Luckily Grace finished its experiment before I could get too anxious about it. It came back to the tunnel with the iron ball.

"You left!" I accused, "Bad!"

"I measured the mass!" Grace defended. "I made a very smart experiment." Smart maybe, but also very unnecessary. To make this point I held up the model, which was just a loop with 26 beads. I held it carefully by the string, so that Grace could hear all the beads.

"26" I said, trying to emphasise the point. Grace spent a moment examining the model.

"ˈaɪərn" It said, and pointed to the model. "ˈaɪərn"

"Iron" I told it, and it recorded the word onto its thinking machine. Somehow it still didn't seem to have made the connection between the model and the iron ball. I reminded myself that Grace was clearly a very intelligent being, from a very intelligent species. I pointed at the model again.

"Iron."

"Iron." Grace repeated. I pointed to the ball.

"Iron." There was a moment where Grace just watched the ball, not responding. Then it brought one of its hands up to slap the top of its head. It seemed it had finally realised what I was trying to tell it. "You are bad." I told it again. Maybe I was a little smug about it, but I don't think Grace understood my tone well enough to catch it.

Grace retrieved a tool from a case on its side of the tunnel, and used it to measure the ball. It reported that the ball weighted 0.3285 kilograms.

"I was only off by one percent." Grace said. It was doing the thing where its voice was low and quiet, as if its words weren't intended for anyone to listen to.

"You talk to you?" I asked it.

"Yes! I'm talking to me." It wasn't the first time I had heard it doing that. I wondered if that was a common trait in Humans, or if this was an individual difference. I decided to give Grace the benefit of the doubt and assume it was cultural.

"Humans are unusual." I said.

"Yes." Grace agreed. I liked Grace. It was an unexpected thought, especially just after being so irritated, but it was true. We hadn't had all that long to get to know each other, but I was enjoying learning its language and mannerisms. I would dare say I would enjoy its company even if it wasn't the first person I had spoken to in almost 50 years.

My muscles had begun to feel sluggish, a sure sign that sleep was almost on me. I stretched out my arms, pushing back against their slowness.

"I sleep now." I told Grace.

"Wow. How long do Eridians sleep?"

"I not know."

"You don't know? You're Eridian, how can you not know how long Eridians sleep?" I didn't take Grace's incredulity personally. It's actually an interesting question; Aside from its first couple of cycles, Grace's sleeping seemed to occur in a regular rhythm. Its surprise made me think that that must be standard in its experience. Did most animals in its world keep regular cycles? Why would that be the case? It seemed like a very interesting topic of conversation for when I was not about to be unconscious.

"Eridians not know how long sleep last. Maybe short time, maybe long time."

"Is there a minimum time? A maximum time?"

"Minimum is 12,265 seconds. Maximum is 42,928 seconds."

"I understand." Grace said. And then it turned to leave. A stab of panic ran through me. Why was it leaving? It wasn't supposed to leave.

"You observe?" I called after it, hoping it didn't understand me well enough to hear the edge of desperation in my tone.

"Not necessary" The words stung more than I wanted to admit. It was one of a storm of emotions that had broken out very suddenly. I needed to calm down. There was clearly a miscommunication happening, and I just needed to clear it up.

"You observe?"

"No."

"Observe." I wasn't yelling. I was speaking in a very reasonable way. Maybe not a very polite way, but I was doing my best. That finally seemed to break through to it.

"You want me to observe you sleep?"

"Yes. Want want want." We had a mutual understanding that repeating a word three times was for emphasis, since we couldn't yet convey that through tone. I felt very emphatically about this.

"Why?"

"I sleep better if you watch." I said, which technically wasn't true. Sleep is sleep, you couldn't really change the quality of it. But I wasn't sure how to say "it would be less terrifying if you watch" in our existing vocabulary.

"Why?"

I wasn't even sure where to begin answering that question. I mean, it's sleep. It's sleep. But then, I'd never seen Grace sleep the way that an Eridian does. It only half slept, still awake enough to respond to the world around it. Were Humans ever forced to submit to the utter oblivion of true sleep? To feel it closing in and know that there was nothing they could do to avoid it? To wonder if they'd wake again in a few hours, or if this would be their final conscious moment?

I waved my arms around, grasping for a way to convey any of that. Finally I just said: "Eridians do that." It would have to do for now.

"Eridians are unusual." Grace said. Yes, I understood what it did there. Very cute. I wasn't in the mood for it.

"Observe. I sleep better."

Grace gestured towards my ship. "Have some other Eridian observe you."

Ah. Right.

I had known for a while that Grace's hearing was mostly limited to whatever room it was currently in. However its sound reception worked, the walls interfered too much for it to hear beyond. I had known that Grace was alone because I hadn't heard anyone else on its ship. If I had taken the time to think about it I would have realised that Grace couldn't do that. It didn't know the rest of my ship was empty.

"No"

"Why not?"

"I am only Eridian here." It was surprisingly difficult to say. I hadn't ever had to say it out loud before, I realised. That shouldn't have mattered. It had been true for a long time, saying it didn't make it any more true. It sure felt like it did though.

Grace's mouth hung open. It floundered for a moment, struggling to start a sentence before asking "You're the only Eridian on that huge ship?"

I hadn't thought it was possible to feel any smaller, but I could feel myself shrinking. I wanted to curl all my hands under me and hunker down for comfort. But hunkering down didn't really work in Zero G.

"Original crew was 23. Now is only me." I said, and I hated how I couldn't keep the emotion out of my voice.

Grace didn't respond immediately. It consulted its thinking machine, as though it needed to check what I was saying. Maybe it had struggled with the change it pitch. I really, really hoped it wasn't going to make me say it again. I wasn't sure that I could. But then its whole body went tense.

"They... did they die?"

"Yes."

"Wh- er," Grace stammered, "Bad"

"Bad bad bad." I agreed.

Grace breathed out heavily, it body loosening in a way that would have had it slumping if there had been any gravity. "My original crew was three," it said quietly, "now it's just me."

It moved and rested one of its hands against the dividing wall. I lifted one of my hands and placed it on the same spot on my side. Our hands are so alike, I thought. I mean, they were incredibly different. Grace's was a soft, fleshy thing with two extra fingers on it. But they both had fingers, and knuckles. Both were made to gesture and count, to hold things and handle delicate tools. We were separated by a centimetre of xenonite, but that distance was insurmountably wide. We were worlds apart, and unbearably close.

"Bad." I said

"Bad bad bad." Grace echoed. The words should have felt laughably inadequate. They should have been too small to carry the weight of so much grief. But somehow it was enough. It was the first time since we'd met that I felt we had truly understood each other.

"I'll watch you sleep" Grace said softly. It was almost on me now, I could feel it. The familiar and terrifying wave of unconsciousness rose to drag me under. But it was going to be okay. I was more sure of it than I had been in a long time.

"Good, me sleep." I barely had time to get the words out before sleep washed over me. The world faded away, for now. The last thing I heard was Grace, with its head turned to watch me.

Chapter Text

Somehow I had wound up with a little workshop set up in the tunnel. It hadn't been an intentional choice, it had just sort of evolved over a couple of cycles. Between sleeping and building our language skills Grace and I were in the tunnel almost constantly. But I couldn't keep ignoring the repair work on my ship, so I brought things to the tunnel to work on them. I ended up bringing more and more tools and equipment into the tunnel, until it resembled a small version of my usual workspace.

During one of Grace's sleep periods I was working on a component from the temperature regulation system. Obviously a key part of its function was to generate heat; Space is very cold, and if you don't warm up your ship then you will freeze to death very quickly. But you couldn't just put a heater in the ship and have it constantly generate heat. If you did that, then the ship would overheat and you would die from the heat instead. So the system was designed to only generate heat if the temperature fell below a certain threshold.

But there was a failsafe measure in the case of overheating. There were a few steel pipes that ran along the outside of the ship, exposed to the temperatures of space. If the ship was in danger over overheating air could be passed through those pipes, cooling it down to the ambient temperatures of space. It would allow the ship to drastically lower the temperature fairly quickly.

During the design phases of the ship building project I had suggested that we could build pipes through the fuel tanks instead, allowing the Astrophage to cool the air. Astropahge would absorb any heat above 96°C, which would lower the temperature much less drastically. But we had ultimately decided that would overcomplicate the design of the fuel tanks, and we had been in a hurry. But now it had given me another idea of how I might use an Astrophage-based cooling system.

Grace shifted slightly in its sleep, and muttered " ˈlaɪtnɪŋ round." Normally that kind of thing happened shortly before it woke up. Grace had explained to me that Humans experience thoughts while they sleep. Their brains spent many of the sleeping hours imagining various scenarios, and Humans would experience them as though they were actually happening.

The idea of a mind inventing new realities while it slept was a little disturbing, although I hadn't said that to Grace. Apparently that sort of thing was normal and expected for Humans. Although I sometimes got the impression that it was distressed by its sleeping thoughts. There were times when its sleep was fitful, and it woke up disoriented and upset. We hadn't really talked about it.

That morning it seemed okay. It took a long, loud breath and began stretching out its limbs.

"Good morning." I said, continuing my work on the device.

"Morning" Grace replied, rubbing its face. It did that every cycle, it seemed to be part of the waking process. "I'm going to eat. I'll be back."

I waved absent-mindedly, still mostly focusing on my work. "Eat." I said, and it made its way back to its sleeping quarters. It had gotten easier as time went by to stop listening to Grace every time it left the tunnel. It helped knowing that it was going to eat, which I really didn't want to listen to any more than I did already.

On the whole, Grace spent more time outside the tunnel than I did. Sometimes it was to go eat, sometimes it was changing clothes, sometimes it just preferred to work on the thinking machine in a different room. I suspected that the tunnel was a little cramped for it; Grace was a lot bigger than me, and the tunnel didn't afford it as much space.

But then, Grace's whole ship seemed quite small to me. Granted, its original crew had been much smaller than mine was. But still. It wasn't a lot of room for three people to spend years of their lives in.

The size of the ship bothered me, actually. Something about it didn't feel quite right. I didn't know much about Humans, but my observations of Grace suggested that they required quite a lot of food. Grace ate solid foods three times during its very brief wake cycle, and liquids throughout. Assuming that was standarad for Humans, then they would need quite a lot of food for a mission lasting several years.

So where was it being stored? I hadn't heard every detail of Grace's ship, there was too much sound interferance to hear everything clearly from the tunnel, but it was hard to imagine there was a hidden room somewhere large enough to contain that much food.

When we had planned our mission, we had decided to bring enough food to last a little over 16 years. 6.64 years to travel to Tau Ceti, 6.64 to travel back, and up to three years to investigate the star. If we couldn't find a solution in that time, we were supposed to bring our findings back to Erid and organise a thrum to decide if there should be a second mission.

Of course things hadn't worked out that way. The journey had not been what any of us had expected. I'd run the numbers many years ago, and I still had enough food left to survive for over 200 years. If I failed to find an answer, I could have outlived all of Erid just by staying on the ship. I had thought about that much too often.

Clearly I was missing something. There was something I didn't know about Humans, or something I didn't understand about space travel, that would explain everything. That wasn't really surprising, there was clearly a lot I didn't know about both Humans and space travel. Despite the best efforts of many specialists we had managed to very badly miscalculate the travel time to Tau Ceti. And the ship and not borne the journey well, even before it spent 46 years in orbit.

Grace didn't seem to spend any of its time repairing things on its own ship. It was possible that was because it was not an engineer, and attempting to fix anything might result in making it worse. But I was inclined to think that the ship simply didn't need fixing. And the ship had arrived in the system without seeming to need any kind of course correction. Human technology seemed better suited to space travel than Erid's. Someday I really hoped Grace could explain some of it to me.

Grace returned to the tunnel, and came right up to the dividing wall to point its face at me. Usually it did that when it had a particular topic it wanted to start with. It even made the "I would like your attention now" noise, so it must have had something important on its mind.

"Rocky, I am here because Astrophage makes Sol sick but doesn't make Tau Ceti sick. Are you here for the same reason?"

Oh, we were having that conversation. I put down the piece I was working on, this needed my full attention.

"Yes. No understand why Tau Ceti not sick but Eridani is sick. If Astrophage no leave Eridani, my people will die."

"Same! Same same same! If Astrophage continues to infect Sol, all the Humans will die." This was great. I mean, it was terrible that both our planets were on the verge of death. But it was great that we both wanted the same thing. It meant that we could help each other.

"Good, same. You and me will save Eridani and Sol." Grace seemed happy with that answer. Humans don't express emotions the same way Eridians do, but I had learnt that the way Grace moved its face was an indicator of mood. Its mouth had stretched out and slightly upward at the corners, which indicated happiness. I was pretty sure that's what it meant, anyway. I has very happy too; finally I had someone to work with. Someone who actually knew things about science. It was an incredible relief to know I wouldn't have to rely solely on my own skills anymore.

Speaking of which... I didn't want to bring the mood down, but there was something else we had to talk about. If we were going to work together, we needed to help keep each other alive. I had no idea what had killed my friends, or how I could prevent the same thing from happening to me. But if whatever happened to Grace's crew was something that could be avoided I wanted to begin taking measures against it immediately. I couldn't think of a delicate way to bring that up, so I went with the direct approach.

"Why did other Humans on you ship die?" Grace's mouth stopped stretching. It rubbed the back of its head with its hand.

"We uh... We slept all the way here. Not a normal sleep. A special sleep. A dangerous sleep, but necessary. My crewmates died, but I didn't. Random luck." An unpleasant tingle ran through my carapace, and I suppressed a shudder. They slept for the whole trip? That would have meant being asleep for years. And with no one to watch over them.

I had already known that the Humans must have been desperate to come here. We certainly had been. But the idea of willingly subjecting themselves to that, with no idea if they would wake on arrival... it was horrifiyng.

"Bad." I said, unable to think of anything else.

"Bad." Grace agreed. "Why did other Eridians die?"

"I not know. Everyone got sick. Then everyone die. I not sick. I not know why." A quaver crept into my voice toward the end. I'd had so many years to grieve my friends, I should have been able to handle it by now. But it was still so hard to talk about.

"Bad." Grace said again. "What kind of sick?" That was an excellent question, for which I lacked a good answer. Sickness wasn't very common, nor was it something I knew very much about. But there had been two doctors aboard the ship, and neither of them understood what was happening either. They had known what was happening to their bodies, but couldn't figure out what was causing it. It was unlike anything any of us had ever heard.

"I need word." I told Grace, "Small life. Single thing. Like Astrophage. Eridian body made of many of these."

"sɛl" it said, "My body is many many sɛlz also."

"Cell." I told it, letting it add it to its thinking machine. "My crew have problem with cells. Many many cells die. Not infection. Not injury. No reason. But not me. Never me. Why? I not know." This was a very hard conversation, but Grace's face was not in its sad configuration. Its face was shaped the way it was when it thought about things.

"I need a word: fast moving hydrogen atoms. Very very fast."

"Hot gas" I said, a little confused. We'd already discussed temperatures and gases. I knew Grace didn't remember things as well as I did, but normally it would at least check its thinking machine before asking me for a word. It shook its head.

"No, faster than that. Very very fast." I wiggled my carapace. What was it asking for? Very very hot gas? That seemed like a simple extrapolation to make, and Grace wasn't stupid. It was asking for something specific, and I wasn't sure what it was.

Grace must have been able to tell I was confused, because it tried to elaborate. "Space has very very very fast hydrogen atoms. They move almost the speed of light. They were created by stars long long long ago."

The conversation was quickly becoming incomprehensible. "No. No mass in space. Space is empty." Space was a vacuum. It was a whole lot of nothing, occasionally punctuated by hunks of matter. Wasn't it?

"No, that's wrong. There are hydrogen atoms in space. Very very fast hydrogen atoms." Okay... hydrogen atoms. This wasn't something Erid scientists knew anything about. But Human technology was more advanced than Erid's, so they could probably detect things that we couldn't. But why did they matter? And why so much emphasis on the speed?

"Understand." I said, although I was only sort of true.

"You didn't know that?" Grace seemed very surprised about that, and it was making me uncomfortable. Space travel wasn't exactly new, we'd had vehicles in low orbit around Erid since the creation of the space elevators. But this mission had been the first to take us beyond our own atmosphere. We had not encountered these very, very fast hydrogen atoms before, as far as I knew.

"No." I said, and Grace didn't respond. It was just watching me, seemingly shocked by my response. The discomfort was rapidly morphing into something sharp and frightening. What did Grace know?

"Why it important?" I asked.

It was a long and very upsetting conversation, which required exchanging and inventing dozens of new words. Grace was very patient through the whole thing, giving me all the time I needed to absorb the information. I think it could tell how difficult it was for me.

I've said already that I'm not a biologist, but I understood the role of cells and DNA in the body. What I hadn't known, what none of us had known, was that stars emitted a kind of energy so powerful it could break DNA apart. And space was absolutely full of this deadly energy. "Radiation¹", as Grace called it. The thing that had killed my friends.

We'd done nothing to protect ourselves. We hadn't known to. And my entire crew had paid the price.

"Thank," I said, not bothering to try disguise the drop in my voice, "now I know how my friends die."

"Bad bad bad." Grace said.

"Yes." I agreed. It was difficult to keep engaging with the conversation through the numbness I felt. Grace kept talking, and I answered its questions about Erid, about our space travel, about all the elements that had conspired to hide the threat from us until it was too late. Our planet, as it turned out, was perfectly formed to protect us from the radiation emitted by Eridani. We had lived on a safe haven for our entire history, and we had left it behind. But there was still something I didn't understand.

"Why did I not die?"

"I don't know. What's different? What do you do that the rest of your crew didn't do?"

Somehow we'd never actually gotten around to talking about our jobs. I hadn't even given Grace my word for "engineer" yet.

"I fix things." I said, "My job is to repair broken things, create needed things, and keep engine running."

"Where were you most of the time?"

"I have room in ship. Workshop."

"Where is workshop?"

"In back of ship. Near engines."

"Where does your ship store Astrophage fuel?"

That seemed like an abrupt turn in the conversation. I waved vaguely in the direction of the back of the ship. "Many containers of Astrophage. All in back of ship. Close to engines. Easy to refuel." Grace exhaled deeply at that. It did that sometimes when it was frustrated or upset. I was suddenly certain that it knew the answer, and that I wasn't going to like it. I didn't want to hear the answer. But I had to hear the answer. Grace's voice was softer as it continued, and hesitant, as though it was wielding something sharp it was afraid to cut me with.

"Astrophage stops radiation." It said. "You were surrounded by Astrophage most of the time. Your crewmates weren't. So the radiation got to them."

It probably would have hurt less if Grace had cut me. I felt hot, and cold, and numb. Astrophage stopped radiation. We'd had the solution the whole time. Millions and millions of Kilograms of it. I could have saved my friends at any time if I'd just known.

Fresh grief washed over me. Grief, and an unexpected spike of anger. It would have been so easy to fix. If we had taken more time, if we had learnt more about space, we could have fixed it so easily. We had been so desperate to launch the mission, in such a hurry to gather information quickly, that we had sentenced the crew to death without even realising it. They were always going to die. It was just bad luck that I was the one shielded by Astrophage.

Grace didn't say anything, it just remained with me quietly while I tried to process everything. Despite it all I was so very, very grateful to Grace.

"Understand." I said finally, when I could trust my voice again. "Thank. Now I know why I not die."

"Radiation is here too." Grace warned me, "Stay in your workshop as much as you can."

"Yes"

"Bring Astrophage to this tunnel and put it on the wall."

For better or worse, I was the last member of the crew. I had to survive. Even if I couldn't solve the Astrophage problem, I had to bring this information back to Erid. We couldn't let this happen again. "Yes." I agreed, "You do the same."

"I don't need to." Grace said.

"Why not?"

There was a beat before Grace answered, one that had been getting less and less common in our conversations. I guessed that it was looking for the right words to explain. "Earth's atmosphere is thin, and our magnetic field is weak. Radiation gets to the surface. So Earth life evolved to survive radiation."

"Understand." I said. Once again I was struck by the incredible perseverance of Humans. With no access to xenonite, and while knowing about the dangerous of radiation, they still made the decision to venture beyond their star. And they had done it in a ship that they knowingly filled with oxygen. They were incredible. And insane. And that might just give us a shot at this.

And to make use of that shot, I was going to have to keep my ship working for a little while longer. I picked up my tools again, settling back into repairing the component. Grace's head stayed turned towards me, listening to me work.

"I have a question." It said suddenly.

"Ask."

"Why is Human science and Eridian science so similar? Billions of years apart, but almost the same progress."

I could have pointed out that Humans actually had a lot of technology that Eridians didn't, but to be fair they also seemed to lack a lot of what we had. That was beside the point anyway; On the scale of billions of years, our development was startlingly close together. "Has to be, or you and I not meet. If planet has less science, it no can make spaceship. If planet has more science, it can understand and destroy Astrophage without leaving their system. Eridian and Human science both in special range. Can make ship, but can't solve Astrophage problem."

"Understand. Good observation. Still unusual. Humans and Eridians are close in space. Earth and Erid are only sixteen light years apart. The galaxy is one hundred thousand light years wide! Life must be rare. But we are so close."

"Possible we are family." I said. Grace's face wrinkled, in a way that usually meant confusion, before it sorted through my meaning. Then its face stretched in surprised.

"Oh! You mean... ˈwoʊ" That last noise was meant to convey amazement. Which was appropriate, given the scale of what I was suggesting. Astrophage was capable of travelling through space, and our scientists had already noted the similarities between its cells and Eridian life. It was a logical conclusion that we shared some common ancestor that had also been capable of surviving space. So why not Earth too? Both our planets were within Astropahge's travelling radius, so why couldn't they have been seeded by the same ancestor?

"I not certain." I said. "Theory."

"It's a dɑrn good theory!" Grace said. I couldn't disagree.

It was nice to think that mine and Grace's people might be related, however distantly. There's this belief that some Eridians have, that things in the universe are connected on a scale beyond what we can understand. No, that's not a good way to explain it. Some Eridians believe that the universe is an entity. A being with a consciousness, if one vastly different from anything we would understand as consciousness. They believe that events occurring in different places are connected in the same way that the movement of my lungs is connected to the sensation of water dripping across my fingers. It wasn't that one was directly impacted by the other, or that something had deliberately brought the two things together. They were simply processes occurring in the same body, connected by my conscious experience of them.

It wasn't something I necessarily believed myself. But being here with Grace, light years away from our respective worlds, it was impossible not to marvel at the way we had been connected to each other. At how after billions of years of divergent evolution we were here, learning how much we still had in common. It was almost enough to make me rethink my entire understanding of reality.

The enormity of events that had to conspire to have me and Grace meet here was overwhelming. First, (theoretically), a life form capable of surviving in and travelling through space had journeyed many light years to seed both mine and Grace's worlds. From that seeding, both worlds had evolved life forms capable of scientific study, which was hardly a guaranteed outcome.

Then, billions of years after the first seeding, and almost at the same time, a descendant of that life form had infected both of our stars. And it just so happened that we had both been in the specific range of development that made traveling to Tau Ceti a viable way of finding a solution. Then, through tragic circumstances, I just so happened to still be in the systen at the time Grace arrived.

There were billions of scenarios where any of those factors didn't quite line up. Countless possible versions of events where Humans and Eridians remained completely unaware of each other's existence. What were the odds that the two planets with intelligent life forms happened to be threatened, and happened to meet here? Impossibly low. So impossibly low that it strongly suggested other possibilities. But I didn't think we were ready to speculate about that yet.

"Very good theory." Grace said again, apparently still processing the idea.

"Thank." I said.

We picked the conversation back up not long after that, and I was happy to go along with it. I was still processing everything I had learnt. I still hurt a lot. But the anger I'd felt had largely drained away. Deep inside I knew that it wasn't actually anyone's fault. We could have spent an 30 extra years preparing for this mission and we still wouldn't have known about the danger of radiation, or how to protect ourselves against it. We had simply done the best that we could with the information we had, and I knew that. Someday I might even accept that it wasn't my fault either.

For now, there was work to do. And I had a pretty good idea what the next step was.

Chapter Text

Human biology is weird.

I'd gotten a brief sounding of Grace's body when it had pressed itself against the wall that first cycle, but that really didn't prepare me for learning about it in more depth. Grace and I spent hours talking about it, as well as talking about my own anatomy. It was something we were both very interested in, because you know. Alien anatomy.

Obviously Humans are mostly flesh, but their squishy organic matter is supported by a skeleton. Their bones aren't like Eridian bones though, they're made of collagen, and minerals like calcium and phosphate. They're technically a kind of organ, and are responsible for producing important cells.

The Human brain is stored in the head, protected by a group of bones known collectively as the "Skull"¹, which connects to a long line of bones called the "Spine"². The spine runs down the back of the body, and the nerves from the brain run through it, branching out to all points of the body on the way down. The nerves transmit information back and and forth by some complicated electro-chemical system.

As I had already noted, Grace's body was almost entirely composed of organic matter. In fact it had so much organic matter that it required over 1,300 calories per day just to operate the various organs, and thousands more to power movement. Even its fleshy exterior was covered by a very large organ called the "Skin"³. Yes, an organ on the outside of the body. That's just how Humans are made.

I even found out what the oxygen was for. Like Eridians, Human cells use oxygen to fuel chemical reactions. Unlike Eridians, their bodies don't recycle the resultant carbon dioxide back into oxygen. That's actually why Humans breathe; it's not for temperature regulation, it's to expel carbon dioxide and take in more oxygen. They can get away with that system because their atmosphere has a very high percentage of oxygen, which is good because they need a LOT of it. Enough that Humans have to breathe constantly, and if they stop for a even a few minutes it can result in severe brain damage, or death.

Breathing brings oxygen to the lungs, where it is passed to the blood, which conveys the oxygen around the entire body, before returning to the lungs to deposit the built up carbon dioxide and absorb more oxygen. Grace could control its own breathing too, to an extent. At my request it was able to demonstrate "holding" its breath, and breathing harder and faster. But most of the time the process is automated by the brain.

"So why Humans sleep?" I asked. I was working on making something new, and it was almost finished. "Not have hot blood, not need cool down. Why need sleep?"

Grace did the thing where it lifted its shoulders and dropped them. That gesture generally means "I'm not sure".

"We don't know exactly why. Some healing happens during sleep, and brains don't work well without it. If we don't sleep for a long time we get sick, and sometimes die. But we don't know all of why." Well, that was interesting, if a little frustrating. But if science had all the answers already we wouldn't need to keep doing it.

"Humans can control sleep? Sleep when want? Wake when want?"

"A little. If we're awake for a very long time we start falling asleep without meaning to. And sometimes things will wake us up when we want to sleep."

"Amaze. What wakes Humans?"

"Things touching us. Loud sounds. Bright lights. Pain. Sometimes bad dreams can do it." That almost made me stop in confusion. What??

"Light wakes you?" I asked.

"Yeah. Humans need dark to sleep, sleeping in light is difficult."

"How can tell there is light?"

"We can sense light. Like you sense sound." I promptly forgot everything I had been wondering about sleep.

"You hear light??" The corners of Grace's mouth stretched again. I ought to have a name for that, I thought. Maybe I'd call it a smile⁴.

"Yes, I hear light."

"How? How can you hear light?" Grace pointed to the two gelatinous orbs in its head.

"These are special body parts that focus and detect light. They send information to my brain."

"Light gives you information? Enough information to understand room?"

"Yes. Light gives information to Humans like sound gives information to Eridians." Okay. Okay. So Humans have special organs that allowed them to detect light. And that light gave them information about the surroundings. I supposed it must work in a similar way to a camera. Humans just had cameras built into their bodies, apparently.

That thought stopped me in my tracks, and I put down my tools to give Grace my full focus.

"You hear light from space? You hear stars, planets, asteroids?"

"Yes." Grace confirmed. Wow. Just wow.

Wow.

Eridians had theorised about the existence of things beyond our world for thousands of years. Scientists knew that there must be some source from which energy was entering our biosphere, and it couldn't be purely from geothermal activities. But it wasn't until the invention of cameras and the space elevators that we were actually able to perceive the rest of the universe.

We hadn't know about stars. We hadn't know about planets, and galaxies, and nebulas, and asteroids. But Humans had. They had probably known about them before they had been Humans, before they even had a language to name them.

Wow.

And suddenly a lot of things clicked into place. This was why Grace's hearing was so directional. Light travels in straight lines, and Grace's light sensing organs were on the front of its head. And that was why it had so much trouble hearing outside the room it was in; the light wouldn't travel through walls. And the thinking machine! It must have some kind of light-based display! That's why I couldn't hear how it was conveying information to Grace!

"Amaze. What about sound? You can hear sound." I knew that, because it could hear me talking, and when I knocked to get its attention. Grace pointed at the oddly shaped flaps on the side of its head.

"I hear sound with these. it said. I examined the flaps more closely. I could understand how the shape might work for funneling sound, although the way they were angled with favour sound from in front of it. It seemed like an inefficient system, but that aligned with my observations of Grace's hearing. "How do you hear sound?"

I made a vague gesture across my carapace. "Everywhere. Tiny receptors on outer shell. All report back to brain. Like touch." Grace bobbed its head, indicating its understanding.

"I can't hear as well as you do. Without light, I can't understand the room. I can hear you talk, but no more." That actually raised a question. I gestured to the wall between us.

"This is wall." I said, leaving the question implied.

"This is a special wall, light passes through it." I thought back to my first encounter with Grace, and how it hadn't seemed to register my presence at all until I had tapped on the wall. Even then it hadn't actually focused on me until it had found the panel made of this material.

"Amaze. I give you many choices for wall when first built. You choose this because light pass through it?"

"Yes, I chose this because light passes through."

"Amaze." I couldn't stop saying it, because it really was amazing. Light sense. It had never even occurred to me as a possibility. But Earth had a much thinner atmosphere than Erid, so they must have evolved with light as part of their environment. It made sense that at least some creatures would evolve to use it. "I gave choices for different qualities of sound. Never thought of light." Grace checked something on its thinking machine quickly. It had been relying less on it as time went by, but still needed it for some words.

"Just good luck." It said.

"Good luck." I agreed.

There were many more questions I wanted to ask Grace about its world and its people. I could have spent cycles just talking about what it was like to perceive light. But it was going to have to wait for later, because I was just about done with my little project. I picked it up again, and made a few last adjustments before announcing: "I am done."

"What is it?" Grace asked, turning to observe the device better. Observe with its light sensing organs. Which sense light. Crazy.

"Device keeps me alive in small room." I told it. It was an entirely new invention of mine, inspired by Grace's "space suit". That's what it called the small vessel it used to go outside of the ship. Of course I wasn't planning to exit into space any time soon, I planned to leave that to Grace. But it was going to allow me to leave my ship in a different way.

"Wait," I told Grace, and headed back into my ship. I had prepared some sheets of xenonite earlier. It was the same compound that the wall was made of, which was apparently transparent. I would need to let the engineering hive know about that, transparent compounds were very useful for things like cameras and telescopes. It could be difficult to identify good quality ones. Maybe I could run a few more by Grace, while we were here. I brought the sheets back to the tunnel, where Grace was still waiting.

"I make room now," I told it, and quickly began assembling them into two halves of a sphere. Well, it's not technically a sphere because it's made of flat panels. It was like a bad ball, basically. "Room!" I declared when it was done.

"What's the purpose of the room?"

"Room and device keeps me alive in you ship." I explained. Grace's face shape changed. I wasn't sure what the meaning of this configuration was, but I wanted to imagine it was pleasantly surprised.

"You're coming to my ship?"

"Want to see Human technology. Is allowed?"

"Yes! Allowed! What do you want to see?"

"Everything! Human science better than Eridian science." I pointed at its thinking machine, and its toolkit. "Machine that think. Eridians no have that. Many machine in there Eridians no have."

"Yes! Come look at anything you want!" Its voice was easier for me to understand than its face. It sounded excited. I certainly was. There had been many firsts in the course of this journey, and many many firsts in the last few cycles. Now I would be the first Eridian to enter an alien spaceship. What kind of engineer wouldn't be excited about that? What kind of person wouldn't be excited about that?

Grace pointed to the small airlock I had built into the divider wall. "How will you get through that?" Grace was clearly a very intelligent being, but sometimes it forgot obvious things like "I built the wall, I can change the wall".

"You leave tunnel. I make new divider wall. Bigger airlock." I picked up the new device, my new little life support system. Grace's space suit was designed to maintain temperature, atmospheric pressure, control humidity, and supply oxyen. My system was a lot simpler. My body didn't use anything from the air, and I didn't generatre moisture. The only real concern was managing the temperature. Xenonite was an excellent insulator, and I would be at serious risk of overheating if I didn't keep the temperature down somehow. I picked up the device and carefully affixed it to the top of my carapace, over the radiator.

"Is that blocking your radiator?" Grace asked, "Isn't that dangerous?"

"No. This makes hot air into cold air." I explained. Even in the relatively cool air of the tunnel I could feel the chill radiating from the device as I breathed out, quickly lost to the heat generated by my own body. I climbed into one half of the ball, and picked up the other one to cover me. Then I sealed the two halves together with adhesive.

I could have made this with a door, but that would have complicated the shape and introduced more failure points. My atmosphere was 29 times denser than that atmosphere of Grace's ship, if the ball breached it was going to be explosive. I wanted to avoid that happening at all costs. The glue was reliable, and I had the solvent in my tool belt for when I needed to get out.

"I test." I told Grace. The test consisted of floating in the sphere for a little while, just monitoring the temperature. The heat in the ball remained consistent. "Works! Happy!"

"Great! How does it work?"

"Easy." I tapped one part of the device. "Astrophage here. Astrophage take all heat hotter than 96 degrees." Astrophage was a pretty remarkable life form. I might even like it if it wasn't in the process of killing both of our worlds. As it was, I had a hard time feeling postiviely about its many interesting attributes. Perhaps future generations who had never had to live with the terror of the world ending would grow up loving it.

"Clever." Grace said. I tried not to feel too pleased about it. The device wasn't really anything much, but it had been a while since I'd had a cause to invent something. It was nice to have it be appreciated, even if it was very simple.

"Thank. You leave now, I make large airlock for tunnel."

"Yes yes yes!" Grace chimed, and I could definitely tell it was excited now. It collected all its belongings from the tunnel, which took multiple trips. I was not the only one who had been accumulating items while we talked. Once it was safely sealed behind its own airlock, I used the solvent to remove myself from the ball and began emptying my side. That took longer than Grace's had.

Even through the tedious process of moving things around, I could barely contain my own excitement. I was going to enter an alien spaceship. I mean, it was Grace's ship, and it didn't seem so much like a mysterious alien anymore. But it was still an alien spaceship, full of alien technology. I was literally buzzing with anticipation.

In the end I decided to build an entirely new tunnel. It gave me an opportunity to reconfigure my side of it for use with the life support ball, and to add an Astrophage lining to the entire thing. Despite Grace's assurances I made sure its side was lined as well. I had not come this far to lose it to the same thing that had taken my crew.

I also modified it to make it easier to replace. Not that I anticipated needing to make a third tunnel, but I liked to be prepared. Now the tunnel was made with two anchor points that attached to our respective ships, and a midsection that screwed onto them. It would make it easier to remove the tunnel without having to dissolve the glue again.

All of that took a few hours. I had to manufacture the parts inside the ship and pass them to the hull robot for construction, since the completed tunnel wouldn't fit through the airlock. I was planning to use magnets to manipulate things from within the ball, so I included a metal strip along the floor and controls with metal components. And of course, I included an airlock large enough to fit me through.

I did briefly consider making a larger door that Grace could fit through, but in the end I couldn't think of a situation where it would be safe for Grace to attempt it. Its space suit would never withstand the pressure of my atmosphere, and creating a similar bubble for it would require much more complicated life support, which I wasn't confident in my ability to create. Not to mention that if I got stuck on Grace's side, I would be fine for a long time. If Grace got stuck on my side, it would be on a time limit before its oxygen supply ran out. Maybe if I could think of a way to mitigate the risks we could revisit it in future, but for now the risks just weren't worth it.

Eventually I finished the tunnel, and I had to detach the old one from our ships. All I had to do was have the hull robot apply solvent to seams, and then it came away easily with a twist. I let it drift away into space. Trying to hold onto it would have been a pain, I'd either have to dismantle it to bring it back aboard or try to attach it to the hull somehow, and we didn't need it anymore anyway. For a few minutes, Grace's ship was gone from my perception again. I didn't like that. Logically I knew it was still right there, but it sounded like it had popped out of existence. Luckily it only lasted long enough for me to apply fresh glue and attach the new tunnel.

As the glue set I climbed into the xenonite bubble and sealed myself inside. I was fidgeting anxiously, waiting for the tunnel to be ready to enter. I had brought along my tool belt, fastened under my carapace, and two strong magnets for manipulating objects. That was about as ready as I could hope to be for what was about to happen.

I could hear Grace again, already waiting at its own airlock door, pointing its face into the tunnel. It was holding another one of those round devices it was always using.

...huh. Grace had said that it couldn't understand a room without light, but I had never built any light sources into the tunnel. To be using its light sense it must have been bringing its own in with it. Was that what the device was for? Light? It would explain why it had gone to fetch it before our first meeting. It always turned it off before it slept too, and Grace had said it had trouble sleeping in light. It was almost anticlimactic to realise after I had wondered about it for so long. But there was no time to worry about that, I had an alien spaceship to investigate.

Using my magnets I moved a lever, and Ammonia rushed into my side of the tunnel through a pipe along the ceiling. A second lever filled Grace's side with oxygen. I shuddered a little, unable to help myself. While constructing the tunnel I had come to terms with the fact that it was bad safety practice to rely on Grace to pressurise its side of the tunnel, without having a way to do so from my side. Of course it was also bad safety practice to have oxygen aboard a ship, but some risks were necessary.

I already had carbon dioxide on the ship, since it was important for studying Astrophage, and I had separated some of it out into carbon and O₂. It was being stored in a tank with extra thick walls. Was I being a little paranoid about it? Maybe. But I would rather be overly cautious than on fire.

With both sides of the tunnel pressurised, I opened my airlock and floated in. Grace watched from the other side of its door- I guessed that at least some of the door must be transparent too- and I used a free hand to wave at it. It waved back to me. I moved the magnets down to the bottom of my bubble, and the magnetic force caught the metal strip along the floor (I had decided that it was technically a floor for now, since I would be using magnetic force to attach myself to it. It wasn't the same as gravity, but it was close enough for these purposes).

The whole bubble was pulled downwards by the magnets, and I landed with a "thunk". It was oddly satisfying. I wondered if I could incorporate the use of magnets into pacing in Zero G. If I held a magnet in each hand and made an iron plate that I could "walk" across it would almost be like having gravity. I shook the thought away. I could figure that out later, it was time to focus.

Using the magnets I rolled the bubble along until it reached the dividing wall with its new, bigger airlock. I had already gotten the hang of using the magnets to manipulate the controls, and easily cycled myself through it. Another little shudder ran through me as the airlock filled with oxygen. In theory there was no reason that any of this would go wrong. The bubble was effectively the same as the dividing wall, just with a different shape. It could handle Grace's atmosphere easily, and I wouldn't even feel any different from being on my side of the tunnel. But it still made me nervous to know I was now surrounded by oxygen.

Nothing disastrous happened as the airlock pressurised. It was just simple engineering working exactly as expected. Nothing to worry about. I opened the airlock, entering Grace's half of the tunnel for the very first time, and rolled all the way up to its outer door. Memories of visiting my friends as a child ran through my mind, of nervously waiting for a parent to let me in after knocking.

This time there was no need to knock. Which was good, because I was in a bubble and couldn't actually knock on the door itself. As soon as I approached Grace pulled open its airlock, looking down at me and smiling widely.

"Hello!" It said.

"Hello!"

"So... do I carry you around? Is that the plan?"

"Yes, carry. Thank." Given a lot more time and resources I might have been able to devise a way to move myself around, but I didn't really have either of those. Grace's ship was made of aluminium, which was non-magnetic, so I couldn't use my magnets to move myself along the floor. And I couldn't exactly install metal strips through Grace's ship for myself. If I was going to get around, Grace was going to have to move me.

Grace gingerly touched the bubble, before grabbing onto it properly. The air inside would have been too hot for its delicate skin, but I had accounted for that when building the bubble. The xenonite was just a little thicker than the dividing wall, thick enough to keep the heat from leaking out and burning Grace.

It took a moment for Grace to get the bubble moving, and it was a noticeable strain for it. Obviously there was no gravity, but objects still have inertia. The more mass an object has, the more work it takes to set it in motion, or to halt it when already in motion. I knew Grace's world had less gravity than mine, and it had squishy organic muscles, so even though I wasn't particularly heavy it was a lot of work for Grace to move me. I felt a little bad, but there wasn't much I could do about it.

"You are heavy." Grace commented, breathing harder than usual.

"My mass is 168 Kilograms." I knew the exact weight because we had all been weighed before departure, to calculate fuel usage.

"Wow. You weigh a lot more than me."

"What is you mass?"

"Maybe 80 Kilograms." Maybe? Was it not sure? Surely the Human scientists had also needed to know how much weight was on the ships. Maybe the crew hadn't cared about knowing their own mass. Or maybe it varied. Or maybe Grace had just forgotten.

"Humans have very small mass!" I chirped.

"I'm mostly water." Grace explained, and heaved me through the door into the first room. "Anyway, this is the control room! I operate the ship from here." It was a fairly empty room. It had chairs, and a lot of flat surfaces. Also some clutter that had previously been in the tunnel. There were very few buttons or levers. I didn't like that. There should be buttons and levers for controlling the machines. But I didn't know how Human technology worked, maybe this way was better for them?⁵

"Understand." I said, choosing to follow up those thoughts later. Grace took this as a cue to begin moving me to the next room. That involved travelling down a short tunnel, into a room that had many, many more things in it. This was the room Grace would occasionally fetch items from. I skittered around inside the bubble, trying to hear as many angles as possible. Sound passed through the xenonite just fine, but it could still be difficult to get good details while floating in a bubble in the middle of a room.

"This is my lab." Grace told me. I had to restrain myself from squealing with excitement. The science room! Where science would happen! All of these things were science things! Any piece of equipment in this room might be crucial in finding a solution to the Astrophage crisis.

"Good good good room!" I squeaked. "Want to understand all!"

"I'll answer any questions you have." Grace promised.

"Later. More rooms!" Grace's ship was small, and I knew there couldn't be much more to see.

"More rooms!" Grace echoed, pushing me onward. The third room was the one where I heard Grace sleeping, before we had started watching over each other in the tunnel. It was also where it went to get its food while I tried to ignore it.

"I sleep here." Grace said. "Well I used to. Then you made me sleep in the tunnel."

"You sleep alone?" I asked, although I already knew the answer.

"Yes."

"I also sleep alone many times. Sad sad sad." Grace didn't comment on that, instead moving to open a panel to another compartment.

Grace had explained this before. Humans don't have the same instinctual terror of sleeping alone that Eridians do. On Earth Grace slept alone the majority of the time, as did many other Humans who didn't have partners, or who simply preferred not to share a nest. But I couldn't help but be sad for it anyway. Three Humans had fallen asleep in this room, with no one to watch over them. Two of them had never woken. I hadn't been able to help my friends, but none of them had had to sleep alone. It was the only comfort I had been able to offer them. I was sorry that Grace's friends hadn't had that. I was sorry that Grace had had to wake up alone.

Grace pushed me towards the open panel, without pushing me all the way in. Probably because there was not very much room inside. "This is a small room for storage." It said. The room was full of soft boxes, the contents of which I could only guess at.

"Understand". I said, and Grace pulled me back into the dormitory.

"That's all the rooms. My ship is much smaller than yours." There were more spaces I could hear around the ship, but I guessed that those were not spaces Grace had access to. At least some of them must be for fuel storage, with a lot of fuel being used up from the trip here.

It really was very small, considering how much larger Grace was than an Eridian. Why had they limited the space so much? Earth gravity was weaker than Erid gravity, which would have made launching objects with a lot of mass much easier. They had Astrophage too, which was an incredibly potent fuel source. I knew from experience it could easily move a ship many times this size. Why not include a larger ship that could accommodate more Humans? Or just give the three they were sending more space?

I filed the question away with my other niggling concerns. It was something I could ask about later.

"You ship has much science!" I said instead. "Show me things in science room?"

"Sure." Grace dragged me back into the lab. It was actually quite interesting to listen to its body working. With it touching the bubble I could hear the straining of its muscles, and the way its heartbeat and breathing increased. It was a little gross, but I knew the biologists on Erid would be thankful for the information.

We reached the lab, and I turned excitedly to take the room in better. The room was full of devices that I couldn't begin to guess the functions of. I'd had enough trouble trying to identify the scientific equipment in our own ship lab. Grace pushed me to the middle of the room, so that I was hovering over a table.

"Use your magnets." It said. I moved them down towards the surface, and the magnetic force pulled me down onto it.

"Good!" I chirped. Now I had a stable surface to sit on while Grace explained the equipment to me. I rolled the bubble back and forth a little, getting a feel for it. It was a little clumsy, but serviceable. Grace floated away from me, hovering at the edge of the room.

"There's a lot here. What do you want to know about first?" That was a very good question. There were so many strange and unfamiliar things in the room. My attention would land on one thing, and the immediately be drawn to something equally intriguing. Finally I just picked a random object and pointed to it.

"That. What is that?"

"It makes small things" Grace said. "I tell the computer a shape and it tells this machine how to make it." I had not known that the thinking machine could do that. That sounded incredibly useful. I wondered what the limitations were. How small did the object have to be? What did it make them out of? How complicated a design could it produce?

"I can watch it make small thing?" I asked hopefully.

"It needs gravity." Grace said. Interesting. That seemed like a terrible limitation to work with in space. I remembered back when I had sent the first capsule to Grace, which seemed like a long time ago despite only being a few cycles. Shortly after it had received the capsule the entire ship had begun spinning. Presumably during the period when it would have been running tests on the capsule. I remembered the centrifugal force I had experienced while my own ship spun. That gentle half-gravity. Maybe that had been the intention.

"That is why you ship rotates?" I asked.

"Yes! It makes gravity for science things."

"You ship can no rotate with tunnel attached."

"Right." I thought about that for a minute. I had spent 46 years in this system, failing to solve the Astrophage problem. The simple fact of the matter was that I couldn't do it, not with my skills and not with the equipment on my ship. Grace had lots of scientific equipment, and was a scientist. It seemed obvious that our only path forwards was for Grace to study the Astrophage, which it couldn't do with my ship attached to its.

I made a decision. "You ship has more science than my ship. Better science. I bring my things into you ship. Release tunnel. You make you ship spin for science. You and me science how to kill Astrophage together. Save Earth. Save Erid. This is good plan?"

Grace's face stretched in a way that I thought meant surprise. "Uh... yes! Good plan! But what about your ship?" It reached over and tapped on my bubble. " Human science can't make xenonite. Xenonite is stronger than anything Humans have."

"I bring materials to make xenonite. Can make any shape."

"Understand. You want to get your things now?"

"Yes!" I said. The sooner we moved things over, the sooner we could release the tunnel, and the sooner Grace could demonstrate its scientific equipment to me.

"Okay! Let's get started I guess." I moved my magnets to release their grip on the table, and Grace began the laborious task of pulling me back towards the airlock. I suppressed the urge to fidget and skitter, not wanting to shift my mass around while Grace was carrying me. It was difficult to contain myself.

This was it. We were really doing it. Working with Grace had been my intention since I first initiated contact, and now we were finally here. I could tell I was getting a little ahead of myself; There were still many hurdles in front of us, and we didn't even know what all of them were yet. But there was a chance now. In a few years, I might be back on Erid with the answer my people needed. In just a few years. I just needed them to wait that little bit longer for me.

Chapter Text

If you had asked me before, I would have said I hadn't brought many "things" with me on the mission. It wasn't as though I had much in the way of personal items. But trying to pare what I was bringing with me to just the "essentials" proved to be a much more difficult task than I'd expected.

Obviously I needed food, and clothes. And I needed enough ammonia to support an atmosphere, with extra in case of an emergency. And of course I brought Adrian's rock, carefully transported in an empty pocket of my tool belt. None of that was too excessive. But the vast majority of my luggage was comprised of equipment and materials.

My understanding was that Grace was not a skilled engineer. It probably had tools on its ship that would be useful for engineering, but I wouldn't know how to use them, and Grace didn't have the training to teach me. So to best use my skills I needed access to my own equipment. Plus I needed the materials to create xenonite, which Grace's ship didn't have.

Even I was surprised by how much I had to bring over. You never realise just how much you need for your work until you have to transport it. I was also unable to help bring all of these items into the ship, since I was confined to the bubble while in Grace's atmosphere. Grace was not especially happy with this arrangement.

"This is a lot of things." It said. It was breathing heavily, and its skin was moist. Grace told me that that is a cooling mechanism; The evaporation of the moisture draws heat away from the skin. Humans are very leaky. It had been hauling bags in from the airlock for over an hour now, and the dormitory area was almost entirely filled with my things.

"Yes yes, I need these things." I assured it.

"A lot of things" Grace repeated. I noted that Grace got grumpy when exerting itself. It wasn't as though I wouldn't have helped if I could. And I was the one who'd had to pack all the bags and bring them into the tunnel in the first place, so it wasn't as though I'd done no work.

"Yes yes, understand. Things in tunnel is last things."

"Okay." Grace grabbed the last of the things, floating them down to the dormitory and jamming them wherever they would fit. I was going to have to organise everything, to try and maximise our space. I was also going to need to build myself an area that could contain my own atmosphere. I would be of very little use to Grace or the mission trapped in the bubble.

I surveyed the room, taking stock of the space. There were still a couple of clear spots, around Grace's nest and in the area where I intended to sleep. A habitat zone large enough to accommodate my supplies and give me room to work would probably take up the majority of this room. I wasn't sure how Grace would feel about that, but it was for the sake of the mission after all. It would have been much easier if Grace's ship weren't so small.

"Are we done?"" Grace asked, interrupting my thoughts.

"Yes. Now detach tunnel." Grace made an unhappy noise.

"You made the tunnel, you detach it."

"How I detach tunnel? Me inside ball."

"Well how do I do it? I don't understand xenonite."

I gestured the act of turning with two hands. "Rotate tunnel." It was a good thing I had decided to make the midsection of this one detachable. It would have been much more annoying to have Grace attempting to apply solvents to the seal. Of course I had intended for the hull robot to be doing the rotating, but I couldn't control that while I was on this ship.

"Okay, okay," Grace grabbed its space suit. "ʤɜrk"

"No understand last word."

"Not important." Grace climbed into the back of the life support suit, closing it up behind it. It got really grumpy when it was working. I fidgeted a little as I listened to it cycling through the airlock. As the air was pumped out the sound of Grace became indistinct, until I couldn't hear it at all unless it made contact with the wall. It made me nervous, even though I knew it was only in the tunnel.

I could at least hear when it began rotating the tunnel. It took it some time to shift it, but eventually it managed to twist it far enough to detach from the anchor points. And just like that, my ship was gone.

The anxiety I felt at that was unexpected. That ship was all I had known for almost 50 years, and it was gone. Vanished into the lifeless void of space. After all this time I hadn't considered what it would feel like not to be able to hear it anymore. And with Grace floating in the vacuum, I suddenly felt very alone.

Thankfully Grace wasn't gone for long. It cycled back through the airlock, fading back into existence with the air pressure. I decided to busy myself with tidying my bags, to try and diffuse the tension I felt.

It returned to the dormitory, and hung onto a free nest to watch me work. Each of the bags had a metal clip on them, so I could anchor myself to one of them and shift around the others with my magnets. Despite my best efforts I occasionally dislodged myself, and Grace had to get up to move me back to the boxes. It complained every time it had to do it. It also loudly lamented that it didn't have a large tub of warm water to soak in, which was apparently something that Humans did.

It was nice, listening to Grace complain. And I did a great job at not being consumed by the feeling that the universe had just shrunk down to a ship 49 metres in length. But it was still a relief when Grace decided we should get to work.

"Okay," it said, "step one. Astrophage sampling"

"Yes yes." I held up two hands, and used one to circle the other. "Planet move around Tau. Astrophage go there from Tau. Same at Eridani. Astrophage make more Astrophage with carbon dioxide there."

"Yes. Did you get a sample?"

"No. My ship had device for this. But device broke."

"You couldn't fix it?" I suppose I should have been flattered by the note of surprise in its voice. Grace always seemed very impressed by my engineering work, no matter how modest.

"Device not malfunction." I clarified, "Device broke. Fell off ship during trip. Device gone." Which I hadn't discovered until I reached Tau Ceti. I wasn't even sure when in the journey I had lost it. Finding out had been a very difficult time for me, and I didn't like to think about it.

"Oh! Wow. Why did it break off?" I wriggled uncomfortably.

"Not know. Many things break. My people make ship very hurry. No time to make sure all things work good." We'd hurried too much, I knew now. But even if we had taken more time, it wasn't as though we would have known what to prepare for. Besides, it was done now. There was no point dwelling on it. "I tried to make replacement. Failed. Tried. Failed. Tried. Failed. I put ship in path of Astrophage. Maybe some get stuck on hull. But robot on hull no can find any. Astrophage very small."

Thinking about it brought it all back to me in a rush that made my carapace slump as low as it could go. Failure and despair, compounded by grief. My voice came out low and pained.

"Fail fail fail. I am repair Eridian. I not science Eridian. Smart smart smart science Eridians died."

"Hey... don't think of it like that..." Grace said. It's face was folded in sad ways.

"No understand."

"Uh..." Grace pulled itself away from its nest, and moved over towards me. It tended to move closer to me whenever it was trying to be comforting. I suspected that touching was something Humans did to comfort each other, like Eridians holding hands. Of course we couldn't touch, but I appreciated the gesture all the same.

"You're alive." Grace said, "And you're here. And you haven't given up."

"I try so many times. Fail so many times. Not good at science."

"I am." Grace said. "I'm a science Human. You're good at making and fixing things. Together we'll figure this out."

I thought about that. Simply surviving seemed like a paltry accomplishment in the face of what my crew was sent here to do. But if it meant that I was here at the right time for Grace to help, to find the answer we needed, then maybe that was enough. It still hurt. I think it's always going to hurt. But some of the weight lifted off of me.

"Yes. Together. You have device to sample Astrophage?"

"Yes. I have device for this."

"Relief! I try so long. So many times. Fail." The grief welled up again. "Much time here. Much time alone."

"How long were you here alone?" Grace asked gently.

How to answer that. I could tell it how many cycles I had been here, but I knew Grace struggled with larger numbers. I needed to break the time into larger chunks for it.

"Need new words." I told it. Then I waited while it pulled the thinking machine off a nearby wall. It was never very far away.

"Ready."

"Seven thousand seven hundred and seventy six seconds is a day. Erid rotates one circle in one day."

Grace made a note on its machine. "Eridian deɪ." It said. "A planet rotating once is a deɪ."

"Understand. Erid circles Eridani one time ever 198.8 Eridian days. 198.8 Eridian days is a year."

"jɪr. A planet going around a star once is one jɪr. So that's an Eridian year."

I was glad Grace's people had names for these concepts. Although perhaps that wasn't surprising, since its star was observable to it from the ground. Time keeping on Erid tended to be localise withing clusters, with mostly scientists relying on standardised seconds. On Earth it was probably more intuitive to use Sol to track the passage of time. I made a mental note to ask Grace more about it later.

"We stay with Earth units or you get confused." I said. Not that I was judging, it was just a lot faster to accommodate Grace's mathematical limits. "How long is Earth day? How many Earth days is one year?"

"One Earth day is 86,400 seconds. One earth year is 365.25 Earth days."

I ran the numbers quickly. "Understand. I am here for 46 years."

"46 years?!" Grace's voice came out much louder than usual. It seemed startled. "EARTH years?!"

"I am here 46 Earth years, yes." I confirmed. Grace's eyes were fixed on me, its face stretched.

"How... how long do Eridians live?"

I wiggled a finger vaguely. It was hard to be exact with life spans. "Average is 689 years."

"EARTH years?"

"Yes." I said, perhaps a little more sharply than I'd usually speak to Grace. I might have been getting a little annoyed. I was always very careful to keep things simple for Grace. Always defaulting to its grammar, to its units. It wasn't really hard, but it could still be a little tiresome to constantly change how I naturally spoke. I felt like I was never properly speaking my own language. So maybe I was a little more irritated than was really warranted by the questions. "Always Earth units. You are bad at maths, so always Earth units."

Grace didn't respond to that for a moment. It just watched me with its light-sensing orbs. Eventually it asked. "How many years have you been alive?"

"291 years." I told it. Then I added "Yes, Earth years."

Grace finally moved its orbs away from me, pointing it off at a wall while holding its head with one hand. I recognised this as its "running numbers" pose. It preferred to face away from me when it was doing that. This information seemed to have started it for some reason.

"Why you so surprised? How long do Humans live?"

"Uh... about 80 years?"

I wasn't sure what answer I had been expecting, but that was definitely not it. 80 years??? These creatures that did science and built ships and walked through space only lived 80 years??? It was so shocking I couldn't even respond for a minute. Finally I blurted out: "Earth years?"

That made a sound burst out of Grace. I'd heard it before, that was how Grace laughed. It was very different to the trilling sound made by Eridians, it was more like a loud exhalation. Or sometimes a series of them.

"Yeah. 80 Earth years."

"How old are you?"

"Twent-" It cut itself off mid word, and its face folded in a way I didn't recognise. Human faces are so complicated. "No, I guess I'm about 33 now? Maybe 34?"

33 years old. Most Eridians wouldn't even have finished growing at that age. Grace was younger than many still considered children on Erid.

"You are not certain?" Grace smiled, which normally meant happiness. This didn't seem like the usual happy shape though. Its face was folded the wrong way for it.

"I was asleep for a long time. About four years, I think. But I'm not really sure."

Oh. Right. The Humans had slept all the way to Tau Ceti, for reasons I still didn't entirely understand.

Four years of sleeping. It had already sounded terrifying at the time, but they only lived for 80. It had slept through 5% of its entire expected life span. 10% by the time it got home, assuming it slept again.

The sense of unfairness was overwhelming. Even for someone who knew it was going to happen, and who had agreed to it, it seemed very cruel. I wanted to say something to Grace, to convey the incredible sadness I felt for it in that moment. But I didn't have the words for it. Instead I used my magnets to climb over the boxes, a little closer to Grace. I placed a hand against a spot on the bubble that was close to it.

"Bad" I said. Grace placed its own hand on the other side.

"Yeah. But necessary." We stayed there a moment, hands resting a centimetre apart. Then Grace made a noise "I need your attention" noise. Sometimes it also meant "let's talk about something else". "So, are you done sorting your bags?"

The mound of the bags had not been fully optimised yet, but they were secure enough for what we needed to do next. And I was more than ready to get started.

"Yes." I said.

"Then let's go turn on the gravity."

The transition from Zero G to Earth gravity was very smooth. There was just a briefly confusing direction of forces while the ship's shape was reconfigured, and then it gently accelerated to the necessary speed. The most disconcerting part was having half the ship disappear. I couldn't hear the back half of the ship very well through the cables joining the two halves, so now the universe was about 24 metres long.

I was still in my bubble. Grace was next to me, seated in front of the Hail Mary's primary thinking machine. That's what Grace called its ship, the Hail Mary¹. Apparently naming things is an important behaviour in Grace's culture. It had even named my ship the "Blip-A". I didn't really get it, but it was helpful to have a way to differentiate between them besides "your ship, my ship".

Gently I tested the gravity, bending my elbows and hopping a little. It was a pretty weak force, similar to the space elevator. And similar to what I'd experienced when rotating my ship. But weak as it was, it was nice to have a floor again.

"This is Earth gravity?" I asked, still bouncing my elbows and shifting my weight from side to side. Grace turned its head to check the thinking machine screen. It was strange to think that there was so much information there, completely inaccessible to me.

"Yes. this is Earth gravity." It confirmed.

"Not much gravity. What is value?"

"9.8 metres per second per second." I converted the numbers mentally. That was a little under half of normal gravity.

"Not much gravity." I repeated. "Erid gravity is 20.48."

"That's a lot of gravity." It commented. I wondered for a moment if the Hail Mary would be able to handle accelerating at the speed necessary to simulate Erid's gravity. Not that we'd want to try that. Grace's squishy body probably wouldn't be very well suited to working under that kind of force. It struggled enough in Zero G.

"So," it said, leaning back in its seat and turning to face me, "What's the plan? Fly into the migration line and get some Astrophage?"

"Yes! But first I make xenonite room for me." I'd been turning the design over in my mind and had mostly figure it out now. I gestured back to Grace's dormitory. "Mostly in sleep room. But tunnels in lab and small area in control room. Is okay?" I would need the space to do our work, but I wasn't going to start modifying Grace's ship without its approval.

"Yes, that's fine. Where is the xenonite?"

"Xenonite parts in bags in dormitory. Liquids. Mix. Become xenonite."

"Interesting! Someday I want to know all about xenonite."

I could have told Grace all about the tensile properties of various xenonite compounds, how they absorbed sound, their conductivity, how to gauge the quality by the sound, and any number of its infinite uses in machining and construction. None of which was what Grace was really interested in. I was an engineer, not a chemist. And Grace was... some kind of scientist². I actually wasn't sure what its specific expertise was, but it definitely wasn't engineering.

I not understand science." I admitted. "I just use. Apology."

"That's okay. I can't explain how to make a thinking machine. I just use it."

"Good, you understand." That was a shame though. I would have loved to hear about how the thinking machine was made.

"How long will your xenonite construction take?" Well, I would need to build a fully contained space, since Grace's hull probably couldn't contain the necessary pressure. And I would need to build tunnels through some of the walls. I was certain I could do that without compromising Grace's ship, but I'd want to be careful about it.

"Four days. Could be five days³. Why you ask?"

"I want to work fast."

"Why so fast? Slower is safer. Less mistakes."

Grace fidgeted uncomfortably in its seat. "Earth is in a bad state. It's getting worse all the time. I have to hurry."

"Not understand. Why Earth bad so fast? Erid go bad slower. Have at least 72 years before big problem." I was very aware of that number. It had been slowly counting down in my mind every cycle for almost 50 years.

"Erid is much hotter than Earth." Grace explained, " And Erid is much larger, with a thicker atmosphere. So Erid has a lot more heat stored in the air. Earth is getting cold fast. Very fast. In fourteen more years, most humans will be dead."

The statement hit me like a blunt impact. Fourteen years. And that was just until most Humans were dead. Who knew what would be happening to them in the meantime. I wasn’t sure how long the Humans had planned for Grace to stay in this system, but it had said it took it four years to travel here. So even if we found an answer immediately it would take another four years to get back. How many Humans were going to die just in that time?

I had thought that the situation on Erid was dire. And it was. But I hadn't considered that it might be so much more desperate on Earth.

My voice flattened completely as I spoke. "Understand. Stress. Concern."

"Yes." Grace agreed. Okay, then we didn't have time to work too slowly. We also didn't have time to mess anything up. I would just have to work as quickly as I could while still maintaining reasonable safety. I clicked two fingers together.

"Then we work. We work now! Learn how to kill Astrophage. You return to Earth. You explain. Save Earth!"

Grace released a loud breath from its mouth. That noise could mean a few things. Sometimes it meant that it was frustrated. But its face wasn't pinched in annoyed ways. It sounded more sad than anything. "I'm not going back." It said. "I'm going to die here."

My whole carapace shuddered. I couldn't help it. This conversation was already very stressful, and I was in no way prepared for this addition to it. What did it mean it was going to die here? Was something wrong with it? Maybe it had been sick after all, and I just hadn't realised.

After a moment of stunned silence, and unable to think of anything else, I simply said: "Why?"

"My ship only had enough fuel for the trip here. I don't have enough to go home. I have tiny probes that will return to Earth with my findings. But I will stay here."

"Why is mission like this?" I couldn't keep the distress out of my voice. Grace was talking about dying, here in Tau Ceti, light years away from home. I had no idea how to process this.

"This was all the fuel my planet could make in time."

"You know this when you left Earth?"

"Yes." It's voice was small. This was obviously a difficult conversation for it, and I couldn't blame it. My arms felt weak from stress and shock. They had sent Grace out here to die.

All at once the little things that had been niggling at me clicked into place. The size of the Hail Mary had been bothering me for cycles. It was so little space. It wasn't enough room for food, fuel, or comfort. But if you were only traveling one way, and if you didn't have time to make fuel for a larger vehicle...

Fourteen years. Most Humans would be dead in fourteen years. Every year spent on the mission represented lives lost as their climate turned against them. They had made a choice between three lives and billions of others. I couldn't say I didn't understand that.

Absurdly, out of all the things running through my mind at that moment, I found myself fixating on the tethers. Whenever Grace left its ship, it always brought two tethers, and it always had one attached at all times. The hull of its ship was absolutely covered in tethers points for just this purpose, spaced out so it was always in easy reach of two of them.

Leaving the ship was insane. But Grace did it with robust safety protocols designed to keep it alive. Human engineers had calculated the exact distances between tether points to allow it to move without endangering itself. That's what engineers were for, building things that would ensure the safety of everyone who used them.

I imagined designing a ship like this, pouring my skills and my love into building safety releases in the airlock, and fire suppression systems, and teach the thinking machines to alert the Humans to any dangers. I imagined knowing that no matter what I did, the passengers would ultimately die anyway. That feeling was all too familiar. I imagined knowing, and having to send them anyway. The thought cut so deeply it made me feel wobbly. Our crew had known we were doing something dangerous. We had known we were risking our lives. But we hadn't thought it was certain death.

The sorrow I felt for Grace was overwhelming. I don't think I could ever have fully expressed to it how sorry I was. But it didn't seem like my place to try. Grace had made this choice, knowing the consequences. It didn't need my grief piled on its own.

It was only 33 years old.

"You are good Human." I said, knowing the words didn't convey the weight of the statement.

"Thanks." Grace said. "So, let's collect Astrophage." I couldn't blame it for wanting to change the subject. There were a lot more questions I wished I could ask though. Like why they had had so much trouble producing fuel. When we had been fueling our ship-

Oh, wait.

OH.

"Wait." I cut Grace off in the middle of something about sample collection. "How much Astrophage you ship need for return to Earth?" It was obviously thrown off by the unexpected question.

"Uh... just over two million kilograms." Relief washed over me so strongly I felt dizzy.

"I can give." I said. Grace straightened in its seat, startled.

"What?"

"I can give. I have extra. Can give that much and still have plenty for my return to Erid. You can have."

"Seriously?" Grace's voice had gotten higher. Its heart started beating hard enough that I could just hear it through the fleshy body. Was that supposed to happen? "It's a lot of fuel! Let me repeat it: Two million kilograms. Two times ten to the sixth power!"

"Yes." I confirmed. "I have much Astrophage. Ship was more efficient than planned on trip here." Plus the weight of the ship had been significantly reduced, but I wasn't going to bring that up. "You can have two million kilograms."

What happened next was a little terrifying. Grace's breathing got fast and heavy, heavier than when it was working to move things. Liquid began accumulating around its light-sensing organs. Its heart was positively hammering within its ribs.

"Oh my ɡɑd."

"No understand." I was trying not to panic. If something was wrong with Grace's body I wouldn't have even the first idea of how to do anything about it. I couldn't even touch it through the bubble. The liquid spilled out over its face, and it Grace rubbed at it with its hands.

"You are okay?"

"Yes," It managed to say, not very convincingly, "Yes I'm okay. Thank you! Thank you thank you!"

"I am happy. You no die! Let's save planets!" I was hoping to rouse Grace into action. Or at least get it behaving a little more normally. Instead it bent over, and began making loud noises as liquid poured down its face.

Oh no.

Chapter Text

When I was a child I was passingly familiar with the offspring of a couple that my parents worked with. Their house was close to ours, so I saw this other child reasonably often and we would sometimes be sent off to play together. I had known this child as a quiet, reserved person. It had an interest in games of strategy, and knew the history of our cluster up to 3000 years ago, but didn't discuss either much. In fact, it barely made any conversation at all. Most of the time I hadn't found it very interesting to be around.

Then one day we were joined by a friend of its. That day I learnt that this child was actually a highly excitable and energetic person. It skittered around its friend, talking faster than I could understand sometimes, and trilling at a dozen little jokes the two shared. I had been shocked to learn that there had been so, so much more to this person than I had realised. I realised that I had been stuck perceiving it in a single context. It was as though I had been listening to a single instrument playing, only to have its friend reveal an entire hidden symphony.

The Grace I knew over the next cycle was the same Grace I had gotten to know over the cycles before. But I was discovering layers to its sound that I had never realised were there. The Grace I knew was intelligent and inquisitive. Forgetful, yes, but quick to internalise understanding. This Grace was still all of those things. But it was also jubilant in a way I hadn't known it could be. Grace, in the context of not being condemned to death, smiled widely and often. It made jokes I didn't understand. It listened to music on its thinking machine and hummed along while it helped me to construct my enclosure.

It was nice. It was like Grace had been weighed down by a burden I couldn't perceive, and now it was free and buoyant for the first time.

After our conversation and its very alarming reaction, Grace had eventually calmed down enough to explain that the leaking was something that happened to Humans when they felt very overwhelming emotions. Despite how uncomfortable it sounded it was considered healthy behaviour for a Human.

It spent a while thanking me profusely, while I tried to tell it that it was okay. I wished I could have found the words to say what I meant. I would have told Grace that this was just as much a gift to me as it was to it. When my crew died, there hadn't been anything I could do to stop it. I took care of them, I comforted them, I watched over to them until the very end. But I couldn't stop them dying. The relief I felt at finally having an answer that kept someone alive was immeasurable. Two million kilograms of fuel was a minuscule price to pay for that.

But getting Grace home would come later. First there was science to do.

In the end it only took three days to set up my space in the dormitory, and the tunnels into the other rooms. Space was very limited, so we had to be strategic about what was allowed where. The dormitory was almost entirely my space. All my belongings were stored in there, and I would set up a workshop in the space that was left. The lab just had a tunnel running along the side and up to the ceiling. It would allow me to observe Grace working, but since I couldn't use any of the equipment in there there wasn't a lot of point in me taking over more of the space.

The control room was quite a small space. Once again, there was nothing i could really use in there, so I tried to intrude as little as possible. The tunnel that led up from the lab ended in a bulb that poked into the control room, just next to the hatch Grace used to enter. It wasn't much, but I'd at least be able to watch from there.

Grace helped me to install everything. It grumbled a little about me cutting holes in its ship, but seemed satisfied that I knew what I was doing. That was a lot of trust to put in the skills of someone it had just met, and I appreciated it.

In return, I was placing my faith in it to chart our course. When I had first arrived in the system I had identified the Astrophage breeding planet as the third closest one to the star. Over the first year I had calculated its orbit, speed, size, and approximate mass based on my observations. Along with five other planets in the system, mostly out of curiosity. Grace spent two days using this information to plot a trajectory that would bring us into orbit around the planet, which it told me the Human astronomers had named "Tau Ceti e". Or rather, it spent a few hours plotting a trajectory, and then spent the remaining time obsessively checking and re-checking its work.

It would take eleven days¹ to travel from where we were to Tau Ceti e. Of those eleven days we would only be thrusting for a total of six hours; Three to accelerate, three to decelerate. Again, this was Grace being very cautious and conserving fuel. Using this course we would only need 130 kilograms to move the Hail Mary 150 million kilometres.

Sometimes it was easy to forget how impossibly powerful Astrophage was.

"Boring name."

Grace turned away from its thinking machine to face me. We were in the control room, Grace sitting in its chair and me sitting on the floor of my bulb. It was nice to sit. Before this journey I wouldn't have thought that sitting was something I would miss. Now I couldn't get enough of it. We had to stop the centrifuge while we were doing the initial thrust, because trying to thrust while the ship was in two piece was a terrible idea, but now that the engines were off Grace had got it spinning again. Now it was carefully monitoring our trajectory, rechecking once again that we were following the course as expected.

I wasn't sure if Grace had been intended to pilot the ship, or if it had inherited the role after losing its crewmates. It seemed to know what it was doing, but it also seemed very anxious about it. I could appreciate its abundance of caution, but I was also worried that it might be obsessing. The levity of the last cycle had been nice, and I didn't want to lose it again so soon.

"What? What name is boring?"

"Tau Ceti e². Boring name." Humans might love naming things, but they could also be very lazy about it at times. If you were going to name things it should at least be something interesting.

"Then give it a name." Grace said.

"Me name? No. You name."

"You were here first." It said, unclipping itself from its seat and stretching its arms. "You identified it. You plotted its orbit and location. You name it."

"This is you ship. You name it."

It shook its head from side to side, dismissing the idea. "Earth culture rule. If you're at a place first, you get to name everything you discover there."

Well that was annoying. We had a sort of unspoken agreement not to argue against each other's cultures. It spared us from a lot of minor squabbling, but it was sometimes irritating to be trapped on the receiving end. I didn't want to be responsible for naming a whole planet, it was hard enough having to name Human body parts. But apparently that was the rule. At least it couldn't be too hard to come up with something better than Tau Ceti e.

I thought about it for a while. There wasn't a convention for me to follow here, Eridian scientists didn't tend to name planets. We hadn't even named the ones in the Eridani system. But if we found an answer here this planet was going to be historically significant. Any name I gave it now might well be repeated in the histories of both our worlds for generations.

What do you know. It turned out choosing a name was easy.

"Okay," I said, "Name is Adrian."

Grace dutifully noted the new word in its database. It very rarely needed to consult the machine anymore, but it still documented each word that came up. "What does it mean?" It asked.

"It is name of my mate." I explained. Grace turned to face me. This wasn't something we had talked about before, and I suspected it was surprised by the news. I hadn't exactly been avoiding the subject, but it was difficult to know what to say about it. We didn't have enough words for me to talk about Adrian. Even if we did I probably wouldn't do it justice.

"You have a mate?" Grace asked. Mate was technically not the right word. Adrian and I had never laid any eggs. Neither of us had wanted to, and I wasn't sure if we were ever going to. Adrian was my partner, my love, my closest friend in all of existence, my favourite artist, and the worst strategy game player I had ever met. I couldn't explain all of that though, and I didn't really want to try just then.

"Not known. Mate possibly has new mate. I gone long time."

"Sad."

"Yes, sad. But necessary. Must save Erid." I really didn't want to talk about this. "You pick Human word for Adrian."

Grace thought this over for a moment. I waited attentively. Whatever it picked was going to be the Human word for both the planet and my partner.

"ˈeɪdriən" It concluded, "Human word is ˈeɪdriən." I committed the sound to memory. I fixed it in my mind to the planet ahead of us, and the idea of home ten light years away.

If I thought about it for a while, I could probably come up with some very poetic reason to name the planet after my partner. There was probably a lovely idea in there somewhere about it representing hope, or about bringing a piece of home to this far away place. But the truth was that I just wanted a reason to say its name. Adrian was my favourite word, and it had been a long time since I'd said it to anyone. I missed the sound of it.

"Understand."

I had been awake for a long time, and I could feel sleep drawing closer. I needed to eat before that happened. Another strange thing about moving onto the Hail Mary was getting used to doing the exact same activities I had been doing for the last 46 years, but in a different place. Why did that make a difference? I have no idea. But it felt very strange. I stood up, and started climbing down the tunnel into the lab, intending to head straight through and to the dormitory.

"Where are you going?" Grace called after me.

"Eat." I said, continuing down the tunnel.

"Eat? Wait!" It hurried after me, climbing down its own ladder faster than was comfortable to listen to. Grace was, ironically, not very graceful when climbing. I didn't want it to fall and hurt itself.

"Hey!" It said, "I want to watch!"

I had made it down to the lab floor, but that made me pause. Grace had never seemed to have any kind of issue eating in front of me, and from our conversations I had gleaned that this was normal for Humans. Apparently eating was considered a communal activity in many Human cultures. That sounded horrifying to me, but I could appreciate that it was different for Humans. And I could appreciate that Grace probably didn't have any concept of how appalling its request was to me.

"Is private." I explained patiently. "I sleep after I eat. You watch me sleep?"

"I want to watch you eat." Grace insisted.

"Why?"

"Science!" Okay, yes. Obviously science. I wasn't a scientist, at least not in the way that Grace was, but I understood why the biological functions of an alien species would be of particular interest to it. It wasn't as though I had no interest in Grace's biology, but I was interested in an abstract kind of way.

I shifted a little, part from annoyance and part from sheer discomfort. "Is biological. Is gross."

"Science" Grace repeated, as though this was some kind of irrefutable logic. I could have kept arguing with it. I kind of wanted to keep arguing with it. But I would need to sleep soon and Grace could be incredibly stubborn at times. I fidgeted and wriggled a little more, and then gave into the inevitable.

"Okay. You watch."

So Grace watched me eat. It was highly uncomfortable the whole time. Thankfully Grace seemed to realise this was not something I wanted to discuss further, and it never brought the issue up again afterwards. I moved swiftly on to trying to forget it ever happened, instead focusing on the mission ahead.

The time to Adrian passed uneventfully. Very uneventfully. I... had nothing to repair. The xenonite compartment was holding together perfectly, the temperature regulation worked as expected, and other than some issues with a piece of equipment called the "Spectrometer", the Hail Mary seemed to be in perfect working order.

It was a good thing. I was thinking of it as a good thing.

I was being consumed by unending anxiety.

Repairing my ship had been a constant of my reality for many, many years. Every moment of every cycle I was either fixing something, or allowing the ship to fall into further disrepair. Now there was nothing to fix, and the ship was not in danger of deteriorating any time soon. But that didn't stop the feeling that I was allowing it to fall apart.

I tried to keep myself busy. Grace and I talked about science, and about our homes. Grace enjoyed talking about the history of its planet's space exploration. Apparently Humans had been doing space missions for over sixty years. Sixty years! I had assumed that space travel was something they had developed out of desperation, but long before Astrophage had arrived on their world they had already packed Humans into a highly flammable vessel and sent it to the planet's moon.

Not that Eridians had never gone to extremes in pursuit of science before. Scientists had been launching expeditions to the depths of Erid's oceans for centuries now, aided by little more than an airtight container and enough supplies to last a few cycles. But it didn't make the Humans' space escapades any less shocking to hear about.

Because of their light sense, space has been observable to Humans for their entire history. Sol blocks their view of it for much of the day, but during dark periods Humans can hear stars from light years away, with no special equipment. Humans had been observing the cycles of stars, theorising about their origins, and telling each other stories and myths about them for hundreds of thousands of years. Maybe it was only a matter of time before they ended up exploring beyond their world.

Crazy.

Grace had a lot of questions about Erid too. It seemed particularly interested in the life forms that lived there, not just Eridians. Unfortunately I didn't have a lot of information on that subject for it. Organisms have never been a particular interest of mine, and I knew very little about the way we categorise life, or how it evolved. But I could tell it all about Erid's technology, and it seemed happy enough with that. Talking about the recent developments in mechanics and engineering was probably the closest I got to feeling calm during the trip.

Well, what was the most recent developments when I left. There had probably been advancements since then, especially with the incredibly potent new power source we had discovered in Astrophage. That was strange to think about.

On one of the days we taught each other games from our worlds. Or, we tried to. The only games that Grace had access to were stored on its thinking machine, which I couldn't interact with or even hear any information from. It was still incredible to me how much power one of those machines had. It could store data, solve equations, play music, control various machines in the lab, and apparently run interactive games. I couldn't imagine what we could achieve with just one of those machines on Erid, and Grace had six portable ones hanging around its ship. Plus the main machine that controlled the ship.

I did have all the pieces for Space Catan³ though. The goal of this game is to retrieve resources from around the play area and use them to build up your zones. The rules were fairly simple, and Grace seemed to understand them, but it was a little difficult to play when Grace couldn't actually interact with the game board. Although it did still manage to play better than Adrian.

We briefly experimented with putting the game board in the airlock, and taking it in turns to pressurise with our own atmopshere to use the board. But that made the game take much longer, and Grace kept complaining about the smell⁴. Smelling is something Humans do, it's like tasting but from a distance. Apparently ammonia is a bad smell to them. And also lethal in high doses, although it assured me the residual ammonia on items from my atmosphere wouldn't hurt it.

Despite the difficulties it was a fun day, and I enjoyed spending time with Grace through the trip. But it was never quite enough to fully alleviate the anxiety. And with nothing wrong on the ship I could focus on, I started to fixate on Grace. Suddenly every little thing it did made me worry there might be something wrong with it. Did that face shape mean that it was in pain? Was that noise a sign of sickness? It forgot a word, is it losing its mental faculties?

It was worse when it was asleep and it was just lying there, making noises and shifting around. I had no way of knowing if all those sounds and movements were supposed to be happening. It didn't seem very different from the other times- although I had noticed that its sleep thoughts seemed to distress it less often now- but I had only been observing its sleep for a short while. Would I even notice a subtle difference?

It got so bad that when it was sleeping I couldn't focus on anything but watching it. Counting the seconds between its breaths, cataloguing every noise and movement. I was spending eight out of every twenty four hours just standing near it in my habitat, listening for anything to happen until it woke.

I was doing just that when it woke on the eleventh day of the journey. I listened as its breathing changed, and its body began moving more. It took Grace time to wake up fully, and I waited patiently for its body to cycle out of sleep. Finally its head turned to face me.

"You awake." I said. It was a relief every time.

"Yeah." Grace confirmed. It rose from its nest, and requested food from the robotic arms that lived in its ceiling. According to Grace the robot was also controlled by the thinking machine that ran the ship, and it was able to respond to voice commands. I didn't really have any idea how that worked, it's something to do with teaching it to listen to "phonemes".

Grace looked over to me after receiving its food items. "You don't have to watch me sleeping. It's okay."

I turned to my worktable, considering how to respond to that. I was aware that Grace didn't fear sleeping like Eridians do. But its sleep did scare me. And I couldn't think of a good way to say "I know, I've just been imagining dozens of scenarios over the last few cycles where you go to sleep and never wake up, and I worry that if I stop paying attention for even a moment you're going to suddenly die and I'll be alone again, but this time on an alien ship that I have no control over". It didn't seem like something someone would enjoy hearing.

Besides, even if I hadn't been in the process of losing my mind from anxiety, I think I would still have wanted to watch it sleep. It's what you do for people you care about. You keep them safe, when they can't do it for themselves. I hadn't been able to do that for anyone for a very long time. I wanted to keep doing it for Grace.

"Eridian culture rule," I said, deciding it wasn't the time to explain all of that, "Must watch."

Neither of us spoke while Grace ate. Some of us were raised with some manners, after all. I busied myself with my new side project in the meantime. Since I had no idea what kind of equipment we'd need when we got to Adrian, I'd decided to pass the time by building a device to allow Grace to play Space Catan more easily. It was basically two robotic hands that would be attached to the wall, with controls that Grace could use to move them. It would involve reconfiguring the wall a little, but it seemed manageable. Was it a lot of work to let us play a game? Yes. But it wasn't like there was much else to do.

Grace finished its food and disposed of the packaging, then headed straight for the control room to check our progress. It always did that when it woke up. And before sleeping. And usually at least once more during the day. I wasn't the only anxious person on the ship. But it seemed more confident the closer we got, and the more its observations confirmed our course.

I didn't bother following it, I could hear it just fine from where I was. Even if I couldn't I would have known exactly what it was doing at this point. It was sitting at its computer, tapping away at the screens and listening carefully to all the outputs. After a few minutes it said "We're getting close."

"You know air yet?" I called back, raising my voice a little. While Grace could hear further than it could use its light sense, it still struggled to understand me when I was in a different room if I wasn't loud enough.

I was asking because during the trip Grace had been trying and failing to scan the atmospheric composition of Adrian. The machine that was supposed to do this, the Spectrometer, had been struggling to gather enough data for the scan. Human technology was amazing, but it had also been traveling for four years without anyone servicing it. Grace believed that it might start working once we were close enough to the planet, so it had been checking on it every morning.

"I'll try again now." It said. It tapped some more, and watched the screen as the Spectrometer began its work. It usually took a few minutes for it to report back with insufficient data, so I carried on with focusing on my device. It wasn't complicated, but it would need to be capable of translating Grace's clumsy movements into something fine enough to handle the pieces. I also needed to build it in such a way that the device wouldn't be blocking the game, since Grace couldn't hear around it. Technically I could have used the same transparent xenonite I had used for the wall, but I didn't really want to use up my remaining supplies on this project. So it was a question of arranging the controls and arms in such a way that-

"It worked!" Grace called excitedly.

"Worked?" I hurriedly set down what I was doing, and scrambled through my tunnels though the lab, and up to the control room bulb. "What is Adrian air?" I asked, emerging beside Grace.

Grace consulted the thinking machine. "Looks like its... 91% carbon dioxide, 7% methane, 1% argon, and the rest is trace gases." A large amount of carbon dioxide wasn't surprising. The Astrophage needed it to breed, and seemed to always be drawn to the largest nearby concentration of it. "It's a pretty thick atmosphere too. Those are all clear gases, but I can't see the planet's surface."

"Normally you can see surface of planet from space?"

"If the atmosphere lets light through, yes."

"Human eyes⁵ are amazing organ. Jealous." I meant that too. At some point I needed to learn more about Grace's light sense. Like how far away it could see from, and how much light was needed for it.

"Well, not amazing enough. I can't see Adrian's surface. When air gets thick it stops letting light through. Anyway, that's not important. The methane- that's weird."

I tilted my carapace in interest. "Explain."

"Methane doesn't last. It breaks apart very fast in sunlight. So how is methane present?" By "sunlight" it meant the light from a nearby star. And it was a reasonable question. I knew a little chemistry, but not enough to be of use in this particular conversation.

"Geology creates methane." I suggested, remembering a conversation with a geologist from long ago. "Carbon dioxide plus water plus heat makes methane."

"Yes, possible." Grace conceded. "But there's a lot of methane. 7% of a very thick atmosphere. Can geology make that much?"

That I had no idea about. There was a lot of carbon dioxide in the atmosphere, but I didn't know if there was any water, or what the temperatures on the planet were like. "You have different theory?"

"No. Not really. It is odd, though."

"Discrepancy is science. You think about discrepency. Make theory. You is science Human."

"Yes, I'll think about it." I could tell the mystery was bothering it. It was probably a very interesting question, and if I was a scientist I might have been more intrigued by it. But now that we had the data about the atmosphere I was very keen to move forward with planning what to do next.

"How long until orbit?"

Grace checked its screens again, poking at things that I couldn't see. I really needed to make a system that would let me observe the screens. "Just under a day." It told me. So a little under 24 hours. Before the end of my cycle I might finally have a sample of Astrophage.

"Excitement! Then we sample Astrophage at Adrian. You ship sampler working well?" Admittedly it was a little late to ask about that, and I didn't really have a plan for it if wasn't, but after all my failures I was a little anxious about it.

"Yes." Grace confirmed, continuing to poke at its screens.

"After collection, how sample enter ship?"

Grace made an unhappy noise. "I have to go get it." Of course. Why would anyone do something sensible like build a way to bring the mechanism directly into the ship when you could send a Human out to go get it.

"Humans are amaze. You leave ship."

"Yeah, I guess." I mulled over my word choice. It was very easy for meanings to get lost when you were teaching each other the literal translation of things.

"Amaze is wrong word. Amaze is compliment. Better word is 'crazy'."

"What's that mean?"

"It is when person not act normal. Danger to self."

Grace huffed softly. It was like a laugh, but very small. "Ah," It said, noting down the new word, "ˈkreɪzi. My word for that is ˈkreɪzi."

"Crazy. Humans are crazy." Grace shrugged its shoulders, but I could hear it smiling.

It probably wasn't a good thing that returning to Zero G felt like returning to normal. I had been in space for much, much too long. But I knew that already. We needed to thrust again to decelerate, so Grace had spun down the centrifuge and we were back to weightlessness.

Grace had spent the last few hours before orbit checking and rechecking its numbers. I wasn't sure if I should be concerned with how little confidence it seemed to have in its work, but so far all of its calculations had been working perfectly. Maybe it's a Human cultural thing, where they assume a lack of competence in themselves. Or maybe Grace is just an anxious person. Or maybe it was the "if we make a mistake we'll both die and doom our planets" thing putting it on edge. That worried me too, but I had a good understanding of the extent of my skills.

Despite its anxiety we made it into orbit, and had been falling around the planet for a little under 24 hours without issues. Grace hadn't started up the centrifuge because it was worried about it interfering with sample collection, and because it would only need to stop it again when it had to retrieve the sampler.

It was also very, very excited to be so close to Adrian. Even now it was watching the screen with a big smile stretching its face. From our conversations I had gathered that Grace was not a space explorer prior to the Astrophage crisis, and had not intended to become one. Traveling to an alien planet was not a life experience it had expected for itself, and it was apparently a lot more exciting than traveling to an alien star.

I was listening to it lament that it couldn't visit the planet's surface as I finished my latest device. personally I wasn't sure I would want to do that, but I was sure Voyager would have loved the idea. It would probably have had me designing a landing system to propose to our leading entities when we got back. Voyager and Grace would have gotten along tremendously. The whole crew would probably have liked Grace. Well, Echo would have taken a while to warm to it, but that was Echo's nature. Grace probably could have won it over eventually, especially if it had gotten along with the doctor, who was Echo's partner.

I shook those thoughts away. This wasn't the time to be sad, there was work to do. I made a final adjustment to what I was calling the screen watcher, and the tactile readout came to life. I moved the device left and right, listening as the screen changed to match whatever it pointed at.

"Success! It functions!" I declared. Grace turned around to face me, trying to watch what I was doing.

"What's that?"

"Wait." I said, and pointed the camera towards the screen Grace had been watching. After a moment the readout changed, displaying Adrian in a way I could actually observe. "This device hear light. Like Human eye."

"Oh. It's a ˈkæmərə"

"Camera." I told it, letting it add the information to its thinking machine. "It analyse light and show as texture." I explained, tilting the device so Grace could watch the display.

"Oh, and you can sense the texture? Cool!"

"Thank." I set up the camera on a rig attached to the wall of my bulb, so it was pointing directly at the screen without me having to hold it. "What are wavelengths of light Humans can see?"

"All wavelengths between 380 nanometres, and 740 nanometres."

"Understand." I made a few adjustments to the device, and the readout rippled as the parameters changed. The camera could be adjusted to display many frequencies, but I wanted to have the same information that Grace had. "Now I 'see' what you see⁶."

"You're an amazing engineer." Grace said, watching my readout react to changes in the screens. I waved a hand dismissively, embarrassed by the attention. Grace wasn't familiar with the technology of my world, but being the one to introduce it did not make the accomplishments my own.

"No. Camera is old technology. Display is old technology. Both were on my ship for science. I only modify for use inside." I pointed to the circle in the centre of the display. "This is Adrian?"

Grace checked where I was pointing, and the display on its own screen. "Yes, and that part is green." I knew the word it was using. Different frequencies of light appear different to Humans, and they have different names for them. Grace called them "colours". This was, unsurprisingly, not a feature that we had developed in my language.

"I not have word for this."

"You name it then." Yet more things to name. Would I ever run out of Human things that needed naming? I decided not to spend too long agonising over this one, it wasn't as though it was something Eridians would every actually be able to perceive the way Grace did.

"Yes yes. I name this middle-rough. My display is smooth for high frequency light. Rough for low frequency. This colour is middle-rough."

"Understand. And yes, green is right in the middle of wavelengths that Human can see."

"Good good. Is sample ready?"

Grace checked its screen again. "Yeah, I guess so."

"You get."

"Ugh," Grace groaned, "EVAs are so much work!" EVAs are what it calls anything it does outside the ship. It's an abbreviation of "Extra Vehicular Activities". That seemed like a very dull description for something as remarkable and terrifying as floating around in space, but who was I to judge. And they did seem like a lot of work, but we needed that sample.

"Lazy Human. Go get!" I made sure to emphasise the humour in my tone, so Grace would know I was joking. We had become much more casual with each other over the trip to Adrian, the grandeur and mystique of meeting an alien giving way to the comfortable ease of becoming friends. Grace laughed, and began preparing to fetch our sample.

After it left the ship it stayed out for a long time. Long enough that I began to worry about it. Grace had set up its space suit so that it would sent its voice to the speakers on the ship, which helped with the anxiety of not being able to hear it when it was outside. Not when it wasn't using it though. I could hear the sound of it breathing, but it wasn't saying anything, and I couldn't hear it moving across the hull at all. Luckily Grace had also attached a microphone to my bubble that would let it hear me.

"You out long time." I said. "You are safe?"

It was a relief to hear Grace's voice come over the speakers. "I'm looking at Adrian." It said, "It's pretty." There was something soft in its tone. It was more subdued than it usually was, almost sounding far away. "Pretty" was something to do with sight. It was something that was pleasant to look at, the same way things could make pleasant sounds. I suspected that something was being lost in translation in this instance. And as happy as I was for Grace to have a pleasant experience, I would be happier if it would come inside with the sample.

"Look later. Get sample now."

"You're pushy." Grace said. I'd gotten pretty good at telling when Grace was joking too. It's in the way it emphasises certain words.

"Yes." I said. Distantly I heard Grace moving across the hull. Between the vacuum, the small points of contact, and the insulation under the hull it was difficult to track its movements, but the noise was still comforting. It made it feel less like Grace had vanished from the universe.

Finally it reached the sample, and then made its way back into the ship. It cycled through the airlock, becoming a solid presence again as it re-pressurised. It began climbing out of the suit as it re-entered the control room.

"All is good?" I asked hopefully.

"Yes."

"Good! You inspect with science gear?"

"Yes. Now."" Grace moved over to the controls and began adjusting the settings. "Prepare for gravity!" It was clearly eager to get to work, which was good because I was too. I desperately wanted to confirm that the sampler had worked as expected.

"Yes, gravity." I grabbed onto handholds with three of my hands, getting ready to support my weight. "For science gear!"

Grace got the centrifuge running with no problems, and took the sampler with the precious sample through to the lab. I scuttled along after it, barely containing my excitement. By the time I got there it was already opening up a panel on the sampler device. It smiled as it did so, and it turned its head to face me.

"This panel was white when we started; now it's black." Those were more colour words, but I wasn't sure what the significance of them was in this context.

"Not understand."

"The sampler's colour changed to the colour of Astrophage. We got a lot of Astrophage." With an incredible effort I managed not to squeal. A wave of relief washed over me so powerfully that for a moment I thought my arms my collapse underneath me. Finally. Finally, finally. After all this time, after so many failures, I had a sample. We had a sample. Finally.

I really wished there was some kind of action I could have immediately sprung to. It felt like the kind of moment that warranted immediate action. Unfortunately, science is not known for notable amounts of action. Now that Grace had the sample, it had to spend almost two hours cleaning and preparing it, and them running simple tests. I spent the entire time sitting in the tunnel, waiting to hear the results. After all, even if I'd understood the science of what Grace was doing it wasn't as though there was a way for me to participate.

The sampler had two sides, one that had faced Adrian and one that faced Tau Ceti. It put the samples from the two sides into different containers, and ran tests on them separately. It checked various DNA markers, and confirmed that they were the same as the markers from Astrophage on its own star, and as the Astrophage sample I provided from my ship. Then it checked the population sizes of the samples, and ran into its first anomalous result.

"Interesting" It said. I had been fidgeting in the tunnel, but I perked up at that. Interesting was good.

"What is interesting?"

"Both halves had approximately the same population."

"Not expected." I said. Astrophage was migrating to Adrian to breed. Theoretically that should mean that the population that was leaving the planet should be double the population heading towards it. That was the whole reason our stars were in danger, the constantly doubling population meant that the Astrophage was consuming more and more of their energy. Of course, we couldn't expect the population to be perfectly doubled. There would inevitably be defects that caused some of the Astrophage to die. But that didn't account for the population being almost the same.

"Flaw in counting?" I suggested, "How you count?"

"I measure total heat energy output of both samples." Grace explained. That was clever. Astrophage maintained consistent temperatures, so the more Astrophage there was, the more heat there was.

"That is good method. Population must be same. How?"

"I dont' know." Grace took a swab to the Adrian sample, and smeared it across a small flat piece of material. It took the little flat thing over to a piece of machinery, inserting it inside. I scampered across the tunnel to stay close to it. I know, being nearby didn't really make a difference, and it wasn't as though I couldn't hear perfectly fine from the other side of the lab. I could have heard it just fine from the other side of the ship. But I wanted to be close to what was happening.

"This is what?"

"ˈmaɪkrəˌskoʊp." Grace said. "It helps me see very small things. I can see Astrophage with this."

"Amaze!" Grace moved itself so that its eyes were positioned over a part of the machine. That must be where it sees the small things. I wondered how that worked exactly. There was a chance Grace might be able to explain it, but it could be hard to predict which things Grace understood and could explain and which things it needed to find information in the thinking machines for.

I didn't get to wonder about that for very long though, because after adjusting a dial Grace breathed in sharply. I perked up again. That sound usually meant something surprising had happened. Or that Grace had just injured itself. But the latter was usually accompanied by a "ɡɑʃ dɑrnɪt", it some other Earth expletive⁷.

"Wow!" It said, mercifully not leaving me in suspense, "Life! There's a whole bunch of life in here! Not just Astrophage! A bunch of other species!"

Oh. Oh wow. Somehow that had never occurred to me as a possibility. And maybe that was just me being stupid because why not? Astrophage was an alien life form, why couldn't there be more? I started bouncing around the tunnel, I was so excited I wanted to squeak.

"Amaze! Amaze amaze amaze!"

"Adrian isn't just a planet!" Grace exclaimed, "Adrian is a planet with life, like Earth or Erid! That explains where the methane comes from! Life makes methane!" I knew Grace would come through on the scientific explanation eventually. And what an explanation it was! This was an incredible discovery! A third planet full of life!!! If what Grace said was true there could be a whole ecosystem down there-

I froze as the thought hit me. A whole ecosystem. A whole ecosystem. Life forms that had to consume energy to survive. And Astrophage must be part of the food chain! My whole carapace shot up, I felt almost giddy with the revelation.

"Life is reason for population discrepancy! Life is reason!" My voice was high with excitement, but I didn't care at all.

"What? How, I don't understand."

I tapped the wall emphatically, pointing to Grace's machine and the life sample it contained. "Some life on Adrian eats Astrophage! Population is in balance. Natural order! This explains all things!"

This is why Tau Ceti wasn't dying, when every other star was. Astrophage was an invasive species, breeding with no natural predators to control the population. But if this was where Astrophage originated, if this was where it evolved as part of a balanced ecosystem, then some other species must be keeping it in check.

Grace's face stretched. It's breathing got faster. "Oh my ɡɑd." It said, it's voice wavering, "Astrophage has a ˈprɛdətər! This is amazing! If we find a ˈprɛdətər..."

"We take home!" I squeaked, finishing its thought. "It eat Astrophage, breed, eat more Astrophage, breed, eat more more more! Stars saved!"

"Yes!" Grace yelled. It balled up one of its hands into a fist, and pressed it to the wall of the tunnel. "Fist-bump!"

"What?"

It tapped the fist against the wall again. "This! Do this!"

I balled up my own fist, placing against the same spot on the wall.

"Celebration!" It declared, smiling wider than I had ever seen before.

"Celebration!"

Chapter Text

One of the interesting things to me about Grace is that despite how delicate its body is, it often treats it with very little regard to potential damage. I don't mean things like EVAs, which it at least took reasonable safety precautions for. I mean smaller things, things like the way it uses its body.

Take the brain, for example. Eridian brains are housed in the middle of the carapace, which makes them very difficult to access or damage. But a Human's brain is housed in its head, suspended in fluid. The skull is not nearly as hard or as thick as an Eridian carapace, which means that a Human brain is much more vulnerable. The fluid helps to absorb shock to some degree, but the brain can still be damaged by blunt impacts to the head.

Grace was the one who had explained all of this to me, so I knew that it was aware of it. Which made it confusing to watch it repeatedly smacking its own head with its hands with each word it spoke.

"Why. Isn't. This. Working." I cringed at every strike. The impacts probably weren't enough to do any actual damage, but it was still harder than I liked the sound of. It was a relief when it slumped back against its seat, frustrated by the lack of results.

"No predator?" I asked.

"No predator." It confirmed wearily.

It had been several hours since the exhilarating realisation that Astrophage had a predator, and the mood had somewhat declined since then. Largely because we hadn't been able to find the thing. Grace had immediately set up an experiment to try and isolate it from the sample. The experiment was just a bulb that contained a replica of Adrian's atmosphere, some Astrophage, and a small sample of the life forms from the migration line. Theoretically the predator should eat the Astrophage and reproduce, becoming the dominant population in the bulb. It was a good, sound concept. Unfortunately it hadn't worked.

"You are certain?" I asked, although I didn't actually doubt Grace's assessment. Grace also didn't doubt its assessment, but it dutifully checked the device it had set up to track the experiment's temperature anyway.

"Yeah, I'm sure. No change in Astrophage population."

"Maybe temperature in bulb no good. Too hot. Adrian upper atmosphere is probably much colder than you room temperature."

"Adrian air shouldn't matter. The predator has to be able to handle Astrophage temperature.""

Right. It could hardly prey on something that was 96°C if 22°C was enough to kill it, or prevent it from eating. "Ah. Yes. You are right."

"Maybe predator theory is wrong." Grace didn't sound happy about the idea. I didn't like it either. I paced down the length of the tunnel, trying to think through the problem. As frustrating as the situation was, it hard not to enjoy the simple pleasure of being able to pace properly again. There really was nothing else like it for thinking.

No matter how I came at it, the predator theory seemed like the most logical conclusion. On every other star the Astrophage infected, the population kept growing exponentially until the star's energy output was no longer enough to sustain growth. It couldn't be a coincidence that the one star with a stable population was in the one system where Astrophage was migrating to a planet with an ecosystem. Something here had to be controlling the population growth. But then, we hadn't gotten our sample from the planet. We'd gotten it from the Astrophage migration line. Was there any reason to assume that's where the predator lived?

"Predator is only explanation." I concluded. "Maybe predators no live in migration line. Maybe predators live further down in atmosphere."

Grace perked up a little at the idea. "Maybe!" It turned its head to a screen that I knew had an image of Adrian displayed on it, because I'd left my screen watcher in the control room. "Okay, let's say the predator lives in the atmosphere. What altitude?"

That seemed like a question for a scientist to answer, but by now I knew that talking was an important part of Grace's problem solving process. Sometimes it needed to hear questions posed so that it could arrive at the answers.

"What altitude is best?" I asked it, "If you predator, where you go? You go to Astrophage."

"OKay, so what altitude are the Astrophage at... Ah! There's a breeding altitude. Where air has enough carbon dioxide for Astrophage to breed."

"Yes!" I said excitedly. I climbed back along the tunnel, so that I was standing over Grace. "We can find. Easy. Use Astrophage frequency detector."

Grace made another one of those emphatic gestures, where it made one hand into a fist and used it to slam onto the other hand, which was held open. Hitting its hand was not nearly as worrying as it hitting its head, at least. I wasn't sure if all Humans were this effusive, or if this was simply a facet of Grace's personality. "Yes! Of course! To the control room!"

"Control room!" I echoed. We both made our way up to the control room, Grace following slightly behind me. By the time it took its seat I had already positioned the screen watcher so it was pointing at the main screen that Grace used. It never moved as fast as I did. Whether this was because it was bigger, less graceful, or just because I had evolved for much higher gravity, I wasn't sure. It was probably a combination of multiple factors.

Grace took its seat, poking at the screens to turn on its exterior cameras. After a moment my readout changed, but instead of displaying the planet it filled out entirely with a tactile rendition of low frequency light. It was the frequency Grace's screen associated with the Astrophage, but it didn't actually give me any information.

"What is this?" I asked Grace. "No data."

"Wait," Grace said, poking at the screens again, "We're inside the Petrova line, there's Astrophage all around us. Let me just change the settings to just show the brightest sources..." It took Grace a little time to fiddle with its controls by poking the screens. I still didn't really like the concept of "touch screens". It just seemed far too prone to failure. If a switch wasn't working, I could take it apart, examine the electronics, clean it, and replace it as needed. What was Grace supposed to do if a "touch screen" stopped working? Touch it more?

My readout changed as Grace altered the settings, the shape of the Astrophage concentrations mutating as the sensitivity changed. Finally it settled on a display that showed irregular blotches of very-rough. That was interesting.

"I think this is our answer. Not what I expected." Grace said, echoing my unspoken thought.

"Unusual distribution." I agreed. I had assumed that once it reached the correct altitude it would spread evenly across the atmosphere.

"Yes. maybe the weather affects breeding?"

"Maybe. Can you calculate altitude?"

"Yes. Wait." Grace touched the screens again, and my readout showed the screen was focusing on one particular clump of Astrophage. It made some notes with its Human note-taking equipment, and mumbled a lot to itself. I waited patiently while it did its maths.

"The breeding altitude is 91.2 kilometres from the surface," it concluded finally, "The width is less than 200 metres."

I folded one hand over another. 200 metres wasn't a lot to work with, when moving at orbital speeds. But there were multiple clumps, presumably at a similar height. That wasn't my main concern. my main concern was the altitude.

"If predators exist, predators are there."

"Agreed. But how do we get a sample."

"How close can orbit get?"

"One hundred kilometres from planet. Any closer and the ship will burn up in the atmosphere."

"This is unfortunate." I said, adding it to the list of massive understatements I had made. "8.8 kilometres away from breeding zone. No can get closer?"

"If we hit atmosphere at orbital speed, we die. but what if we slow down?"

"Slow down means orbit no good. Fall into air. Die." The thing about orbiting is that it's actually just a particular way of falling. Adrian was pulling us towards it, but our lateral movement meant that the arc of our fall matched the curvature of the planet. We were essentially perpetually missing the the ground. But if our lateral movement slowed down we would stop missing it, which would be very very bad for us. If we even made it to the ground, and didn't just burn in the atmosphere.

Grace leaned over so it could direct its head at me. Sometimes Grace wanted to face me during a conversation, sometimes it didn't. Sometimes this would change multiple times over the course of a conversation. I had not yet determined all the factors contributing to this, but more important conversations tended to involve more facing me. Generally. It was complicated.

"We can use the engines to keep from falling into the atmosphere. Just thrust constantly away from the planet. Lower ourselves into the atmosphere, get a sample, and then leave."

"No work. We die."

"Why no work?"

"Engines give off enormous infrared light. If you use in air, air become ions. Explosion. Destroy ship."

Grace's face folded a lot. "Right, of course." We both sat in silence for a while, thinking over the problem. At least, I assumed Grace was also thinking about it. It had its head pointed at the wall the way it did sometimes when it had to think. I was trying to think, but I was mostly just getting frustrated.

We were less than 10 kilometres away from getting a sample that might save both our worlds. I've taken walks longer than that, sometimes while carrying sacks of rocks. We had traveled 150 million kilometres across the system to reach this planet. Grace and I had traveled light years from our respective worlds. I had waited here alone for 46 years, and now the solution was blocked from us by less than 10 kilometres of atmosphere. It was infuriating.

"How do you make xenonite again?" Grace asked suddenly. "You mix two liquids?" I perked up. It sounded like Grace might have an idea. Maybe it would be a good idea.

"Yes. Have liquid and liquid. Mix. They became xenonite."

"How much can you make? How much of those liquids did you bring?"

"I bring much. I use to make my zone." That had needed quite a lot of xenonite. I still had some back on my ship, for safety, but I had a lot less overall than when I'd first met Grace. Grace started typing at its computer. The screen watcher showed me a bunch of symbols that I recognised as Grace's numbers. I waited once again for it to do its slow mathematics, keen to see what it had come up with.

"We need 0.40 cubic metres of xenonite." It said at least, "Can you make that much?"

"Yes. Have enough liquids remain to make 0.61 cubic metres."

"Okay. Then I have... an idea."

Some ideas are beautiful in their simplicity. Some ideas are so fundamentally grounded in good logic that they require no complicated mechanisms to ensure that they work. You simply insert them into the situation, and the laws of the universe align around them. This didn't seem like one of those plans, but it was certainly a low-tech solution.

The plan was a chain. Yes, that was the whole plan.

The breeding zone was 10 kilometres lower than we could fly the ship. So we were going to attach a sampler (which I was going to have to design) to 10 kilometres of chain. We get the sample, we reel it back into the ship. Simple.

There was a small complication, in that the chain would be dragging through the atmosphere. Xenonite was a remarkable material, but even it wouldn't survive in the atmosphere at orbital speed. Which meant that we would have to slow down. You may recall that this could make life difficult for us in terms of not crashing into the planet. But that was no problem, because Grace would be thrusting the engines to keep up above the atmosphere. At an angle, so that we didn't vaporise the chain and sampler. That would still ionise the air behind the ship, but it would be behind us, and theoretically we would be outside of the affected area. Theoretically.

I didn't like this plan. I didn't think Grace even liked the plan, and it was its plan. But we hadn't thought of anything better, so this was the plan we were going with.

After we talked about the optimal design for the chain links, Grace spent a little while telling its thinking machine about the shape of the mould that we wanted to make. That done, it took a piece of aluminium and mounted it into a machine. It wasn't the "3D printer" it had shown me before, it was some kind of milling apparatus.

"This will work?" I asked, watching Grace set everything up.

"It should" Grace said. Grace rarely gave definitive answers to questions, but this was normal for scientists in my experience. Everything is a hypothesis until proven. It started the machine, and it began drilling the shape out of the block. It was very interesting to watch.

If I wanted to automate the production of a specific shape, I would need to build a specific machine that would produce just that shape. A machine that was capable of automating multiple shapes sounded like it would be an incredible time saver. I imagined that all the small, fiddly parts that could be created quickly and accurately by machine, rather than slowly by Eridian hands.

The machine finished its work and Grace picked up the aluminium piece, brushing away metallic shavings. It held the block towards my tunnel to show me. That was unnecessary, since I could hear the block just fine from where it was, but I appreciated the gesture anyway.

"How's this?" It asked. The machine seemed to have worked perfectly. It had produced the shape of a loop, with a hole on one side that would let us easily link the chains together. Human technology really was remarkable.

"Very good! We will need many many many chain links." I could have thrown a few more manys in there. By my estimate we were going to need around 200,000 chain links based on our design. "More moulds means I can make more at one time. You can make many more moulds?"

"Well," Grace checked a nearby cabinet, containing more of the aluminium blocks. "I have a limited supply of aluminium"

"You have many items in ship you no use. Two nests in dormitory for instance. Melt them, make blocks, make more moulds."

"Wow. You don't do anything by half measures, do you?"

"No understand."

"I'm not going to melt a bunch of stuff. How would I even do that?"

"Astrophage. Melt anything." The challenge with Astrophage was never how to melt things, it was how to manage its output so nothing got vaporised.

"You got me there. But no. The heat would be too much for my life-support system to handle." Hmm, that was a problem. The delicate, heat sensitive Humans had not designed their ship with a mind towards melting and reshaping metals. But we could just use Astrophage to contain the excess heat, I thought. And if that was still too much I could do the work in my own habitat, which would keep the heat away from Grace's life-support completely-

"That reminds me," Grace continued, cutting off my train of thoughts, "Why do you have so much extra Astrophage?" Wasn't that an excellent question, I thought.

"Strange story." I said. Grace perked up at that. Scientists love strange stories, the anomalies are where all the interesting data lives. I walked a little way down the tunnel, so I could sit in a slightly wider section. "Science Eridians do much maths. Calculate trip. More fuel mean faster trip, so we make much much much Astrophage."

"How'd you make so much? Earth had a very difficult time making it."

"Was easy. Put in metal balls with carbon dioxide. Put in ocean. Wait. Astrophage double, double, double. Much Astrophage."

"Riiight. Because your oceans are hotter than Astrophage."

"Yes. Earth oceans are not. Sad." Grace had told me a little bit about its planet, and how different parts of the world had different "climates". I knew the two poles of the planet were so cold that there was a lot of frozen water on the ocean, and on the land, while other parts of the world were hot enough to cause harm to Humans who didn't take precautions against the heat. That's because of the thinner atmosphere; On Erid the atmosphere traps and distributes heats very evenly, making the entire planet the same temperature all the time. Earth's atmosphere can't do that, so the parts of the planet that are closer to the sun are warmer than the parts further away. The part that was closer changed depending on what stage of its orbit Earth was in. It all sounded very complicated.

But even the hottest parts of Grace's world wouldn't accommodate the temperatures required for breeding Astrophage. The Humans must have been scrambling to find enough heat energy to make the fuel they needed. It had taken so much of the very little time they had just to make enough for a one way trip. I tried to shake off the sadness that came with that thought. Grace was no longer dying here, and it was going to take a solution home.

"Scientists design ship and fuel requirements." I said, getting back to the story, "Journey to take 6.64 years. Strange things happen on ship. Crew sick. Die." I couldn't help the dip in my voice. "Now I know was radiation." The grief welled up again, and I let it wash over and past me. I wondered if it was ever going to get easier to talk about. Grace said nothing, giving me a moment to collect myself again.

"Everyone sick. I alone to run ship. More strange things happen. Engines not work right. I am engine expert. I cannot figure out problem."

"Your engines failed?"

"No. Not fail. Thrust normal. But speed... no increase. No can explain."

"Huh."

I stood up again, pacing a little up and down the tunnel. When my friends died it had been terrifying and awful, but it was a biological problem. If the doctors and biologists couldn't figure it out, I never stood a chance. But I was the engineer, the engines were supposed to be my expertise. But despite spending almost 50 years thinking about it I'd never been able to come up with any kind of explanation for what had happened. It bothered me whenever I thought about it.

"Then more strange. Reach half-way point much earlier than should. Much earlier. I turn ship around. Thrust to slow down. But Tau get further away. How? Still moving toward Tau but Tau moving away. Much confusion."

"Uh-oh."

"I speed up. Slow down. Much confuse. But get here. Even with all mistakes and confusion, I get here in three years. Half of time science Eridians say should be. So much confuse." In the end I had needed less than half the fuel allotted for the journey here. Even if I needed all the expected fuel on the way back I would have a tremendous amount left over. That's why I felt confident giving Grace so much of it.

"Oh... oh my..." Grace said quietly. It seemed oddly distressed. It was a strange and confusing story, but I wasn't sure why it was reacting like this.

"Much much much fuel remain. Much more than should have. No complain. But confuse."

"Yeah... tell me this: Is time on Erid the same as time on your ship?"

Well that was a confusing question. I understood all of the words it had said, and I understood the structure of the sentence, but I had no idea what it was supposed to mean.

"Question make no sense. Of course time is same. Time is same everywhere."

Grace did not seem to like that answer. It put its head in its hands. "Oh boy." I fidgeted uncomfortably. It didn't generally bother me that Grace knew things I didn't. Our specialities were very different, and Humans had had a lot more experience with space travel than Eridians had. But I could sense that Grace had found a large gap in my knowledge here, and I was worried that I might have fallen into it.

"Okay, Rocky." It said finally, "Get comfortable. I have a LOT of science to explain."

200,000 chain links. That's what we would need to get the sampler down to the breeding zone. Grace didn't have a clever machine for linking all these pieces together, so they had to be done entirely by hand.

Even streamlining the process as much as possible, and even with me continuing the work while Grace slept, it took four cycles to create and link all the pieces. First in ten metre rows, and then linking them into twenty, forty, eighty, and eventually stored on spools in segments of 500 metres. There wasn't enough room in the ship to store these, so Grace had to take them out and mount them on the hull. That meant shutting down the centrifuge so that Grace wouldn't be flung off the ship during its EVA, which meant the rest of the work had to be done without the benefit of gravity.

Grace obviously despised it. Apparently Human minds- or at least Grace's Human mind- were not suited to doing repetitive tasks for many consecutive hours. It had to take frequent breaks through its cycle to cope with it, and still complained a lot. It was especially unhappy about having to do it in Zero G.

I didn't mind it. It was a little monotonous, but it was the kind of work where I could easily measure my progress. And it was a vast improvement over the anxiety riddled trip here, when I'd had nothing to do. It also gave me a lot of time to think about what I'd learnt.

The conversation about time dilation had taken hours. I will admit, I did not readily believe Grace when it tried to explain it. And it still seemed inherently wrong now. But despite flying in the face of most of what I knew about physical law, it did align with my observations during the journey to Tau Ceti. It didn't help that neither of us were physicists. Grace seemed to know the basics of what it was talking about, but trying to drill down further required it to research a lot of information on its thinking machine, and trying to clarify concepts it only sort of understood itself.

The simplest version of it that kind of made sense to me was this: If the universe was a two dimensional plane, then space and time would be the x and y axes. If two people cross the plane at the exact same speed, but in different directions, it will take a person moving diagonally longer to experience the same amount of time than a person moving perpendicular to the time axis.

On a fixed frame of reference, like a planet, everyone experiences time and space in the exact same direction. But when you leave the frame of reference- for example jetting off to another star system in a very fast spaceship- you change your angle relative to the time axis. To me, on board my ship, the journey took three years. But to a person observing me from Erid, it would have appeared to take a little over ten.

Yes, that's the easy version. And it was also vastly oversimplified. The full version is unimaginably more complicated. This version of physics hadn't even been discovered on my planet yet, but I had unknowingly stumbled into the effects of it.

There is also apparently a hard limit on how fast anything can travel through the universe. Nothing goes faster than the speed of light, period, and objects with a mass never fully reached that speed. That's why the engines wouldn't produce any more thrust after a certain point, no matter how much power I threw at them. Why? I don't know. I also wasn't sure whether the speed at which light traveled determined the fastest speed of the universe, or whether light was simply moving at the fastest speed the universe would allow. I tried asking Grace about it, but it didn't seem to know.

It wasn't... I still had plenty of time. Erid still had plenty of time. Even with them apparently experiencing seven more years than I had, I still had over 60 years before there were any serious problems. But my clock was wrong.

I thought I had known what the time was on Erid. Of course, scientific standard time didn't matter to a lot of Eridians. Most clusters kept their own time through various methods. But the scientific community largely kept the same clock, and the clocks on my ship had been synchronised to them before we left. I had maintained those clocks all this time, meticulously checking to ensure that they were still in sync. I thought I'd held onto that, despite everything.

I tried not to dwell on it. Once Grace and I found Astrophage's predator, I could actually go home and it wouldn't matter what the difference between my clock and theirs was.

Finally, we had all 20 spools full and mounted onto the hull. Grace had to do the final work of linking them all together, which did not seem like an easy thing to do in a space suit. But in the end we had a single, 10 kilometre chain ready to deploy. We were finally ready to get the sample.

Grace and I were floating in the control room. Grace was performing some final system checks, but I think it was mostly delaying the moment when we had to put the plan into action. I couldn't blame it, I was nervous too.

"Status of probe?" It asked. The probe had been one of my key tasks in this project. The sampler Grace had used for the initial sample wouldn't work for this; Whatever Astrophage's predator was, it lived inside an atmosphere, and we couldn't assume it would survive being brought up into the vacuum of space.

The probe I had designed was essentially made of two spheres, one nested inside the other, with holes along the equator of each. The inner sphere could be rotated, either aligning the holes to allow air in, or misaligning them to trap it inside. The rotation was fully automated; we would send the probe down in the open position, and a pressure sensor inside would detect when it had reached the atmospheric pressure we needed. Then the sphere would rotate closed, and we should have a sample. There was even a thermal regulation system included inside, which would maintain the temperature at whatever it was at the time the sphere closed. I was not prepared to lose this sample over something as ridiculous as overheating or freezing. It wasn't like we had enough xenonite to make another chain and try this again.

The last thing I had included was a radio transmitter, which would broadcast the status of the probe to a console that I had in the control room bulb with me. Humans also use radio signals, as it turns out. Although they also do a lot of other very complicated things with signals that I didn't really understand yet. Grace was very impressed with the setup. It never ceased to baffle me how a person from such an advanced species could be so impressed by simple engineering work. Not that I disliked it admiring my work, but I was a little embarrassed about accepting praise for such small things.

I checked my readouts. Everything was reading as normal. "Device is functioning." I informed it.

"I guess... we're ready?" It didn't sound terribly confident about it.

"Yes." I said. I didn't sound much more confident than Grace did. Grace strapped itself into its chair, and I gripped tightly onto three of my handholds. I did sort of wish I had something to secure myself down with too. Grace's ship didn't tend to deal with any forces as strong as Erid gravity, but it would still be nice to rely on something other than my own grip.

Grace did something with the controls on its thinking machine, which began to reorient the ship. It needed to thrust in the direction opposite to where we had been traveling to slow us down enough for what we needed to do.

"Orientation is good," It reported, "Initiating thrust"

"Yes." I confirmed, gripping tighter. I still had my screen watcher set up to display Grace's screen, and I was listening to it closely. There was a lot of text I didn't understand, but Grace had outlined for me which part of the screen was showing what, and I knew roughly what the numbers meant.

"Here goes..." Grace adjusted another control, and suddenly there was a lot more force on the ship. Grace was pressed back into its chair, and I grabbed with a fourth hand, just to be safe. I reflected that this was a really, really bad plan. Grace's thinking machine was good at processing a lot of data very quickly, but it couldn't predict the kinds of variables involved in a situation like this. That meant Grace couldn't use it to plan this maneuver, it had to fly the ship manually. With each thrust it adjusted our angle and power, trying to find the delicate balance between falling and flying away from the planet. It was a nerve-wrecking experience, knowing that if it got it too wrong we might both die in the atmosphere.

It spent a few minutes doing this, making small adjustments and watching its readouts intently. There was nothing I could do to help with this part. I just had to wait while it figured it out.

"You tell me when to release probe." I said, my free hand hovering over a button on my own little console.

"Not yet." Grace said, not moving its focus away from the screen. Then it turned its head, like something had caught its attention. It was facing a different screen, one it usually used to display the external cameras.

"The engines are heating up Adrian's air a lot." It said, an edge of concern in its voice.

"How you know?"

"Sometimes I can see heat."

"What? Why you know no tell me this?"

"It's related to sight... there's no time to explain it. Just trust me: We're making the atmosphere very hot."

"Danger?"

"I don't know."

"I no like that response." Grace clearly didn't like it either. We were obviously always going to cause some heat in the air, we were firing Astrophage powered engines into it after all. But I don't think Grace would have brought it up if we weren't exceeding what we had expected. The whole reason we couldn't dip down into the atmosphere was because it would burn up the ship. But that was going to be a little redundant if we managed to cause the same damage with our own engines.

But what else could we do? We needed this sample, and neither of us had thought of another way to get it. I clung on tightly, quietly hoping while Grace continued to increase the angle of the ship. Finally it said "Angle achieved."

"Happy! Release?" I wanted to get this over with. The sooner we had the sample the sooner we could leave.

"Stand by. Velocity... 127.5 metres per second! Just what I calculated! ˈhoʊli kaʊ, it worked!" That was encouraging. This part of the plan at least was going to plan.

Now that we were not longer orbiting, I could feel the pull of Adrian's gravity. Of course, we'd still been under the influence of Adrian's gravity when we were in orbit, but we didn't experience it the way we would on the ground. When I said orbiting was falling, I meant that very literally. It's like if you were in a box, and the box was falling from a long way up. Gravity pulls you down, but it also pulls the box down away from you at the same velocity. The inside of the box become a weightless environment, right until it hits the ground. Being in orbit is exactly the same, except without the hitting the ground part. But now we were thrusting up away from the planet, so the floor was no longer being pulled away from us.

My readout of Grace's screen changed suddenly, showing a rectangle with some writing inside. I didn't know what it said, but its sudden appeqrance concerned me.

"Air is hot," Grace said, sounding concerned again. "Ship is hot."

Ship no touch air. Why is ship hot?"

"It's bouncing our infrared back at us. And it's so hot now it emits its own infrared. We're getting cooked." Oh, well that wasn't alarming at all. Getting the sample wasn't going to do us much good if we burnt to death in the process.

"You ship is Astrophage-cooled?"

"Yes, Astrophage cools ship." The Human engineers had set up some clever system that would allow Astrophage to draw heat away from the hull of the ship, keeping the insides cool enough for a Human. I don't think the system was designed with this situation in mind, but heat was heat.

"Astrophage absorb heat. We safe."

"Agree. We safe. And we ready. Drop probe!"

"Drop probe!" I confirmed, and hit the button to do just that. The spools were firmly attached to the hull, so I could just about hear them unwinding and ejecting from the ship in succession. The probe dropped away, and was almost immediately out of my hearing range.

"Spool six away..." I reported. On my screen watcher readout I heard the rectangle appear on Grace's screen again, and disappeared when Grace tapped at it. It must have been the heat warning again. I was a little concerned that it had shown up a second time, but there was nothing we could do about it. We were committed to this course of action now.

"Spool twelve away... Sampler signal good. Sampler detecting air now."

"Good!"

"Good good. Spool eighteen away... air density increase..." The readouts were showing the exact pressure changes we had expected at these intervals. It was encouraging to see the numbers line up so neatly with our calculations.

"Spool twenty away. All spools released. Air density of sampler is almost Astrophage breeding ground level..."

For a few moments we were both silent, as we waited for the probe to complete its descent. It was a matter of seconds, but it felt like an eternity while I watched my console, and Grace watched me. And then:

"Sampler closed!" I announced, my voice pitching up with excitement, "Seal is airtight, heater is on! Success success success!"

"Success!!" Grace shouted. I wanted to yell some more, maybe squeal and jump around in celebration. But we weren't done yet. The sampler had the sample, but we weren't done until we had it safely aboard. Which brought us to the next step of the plan.

"Step two now." Grace sounded considerably less enthusiastic about this. I could sympathise; this next part was probably the most dangerous to Grace personally. I was nervous for it, but it had to be done. And it wasn't as though I could take its place.

Grace unbuckled itself from the restraints, and climbed out of its chair. It was a little awkward, because the angle of our thrust meant that the whole room was tilted. It probably didn't help that Adrian has slightly more gravity than Earth. Not as much as Erid, but enough to make Grace's movement a little more difficult. Then it climbed into its space suit, and retrieved the winch I had designed especially for this next task.

The sample was currently 10 kilometres below us. It was obviously no use to us there, so we needed to reel it back in and bring it into the ship. Or more accurately, Grace did. It would have been nice to pull away from the planet before doing this, but we couldn't actually thrust directly away without vaporising the sampler with the ship's engines. Which meant that Grace was going to have to do this EVA while under the full effects of Adrian's gravity.

"Be careful." I told told Grace as it moved to the airlock. "You are friend now." I didn't feel awkward about saying it. Grace was not just my best hope of saving my planet, it was a person I cared about. I would be devastated if something happened to it. I really hoped I wasn't sending it out there for something to happen to it.

"Thanks. You are friend also."

"Thank."

And with that Grace stepped into the airlock, cycled through, and opened the door out into space.

Chapter Text

There was nothing for me to do except listen as Grace made its way across the hull. It was easier to track than usual, with gravity keeping it firmly rooted to the ship. Getting out had been tricky; The outer airlock door was facing away from the planet, so it had had to pull itself and all of its equipment up to get out of it. It had taken it a few minutes, and I heard a lot of profanities over the speakers.

My whole body was tense as I listened to its footsteps. Normally if Grace slipped during an EVA, the worst that would happen is that it would drift away from the ship. There was little actual danger in that because it always had at least one tether attached to the ship, and could just pull itself back. But now if Grace slipped, it might fall off the ship. It was still using the tethers, but I had no idea if they would actually be able to take its weight if that happened. I was a fidgeting mess of nerves. All it would take was one wrong step, and Grace was so clumsy.

Its footsteps stopped at the point where the chain had been anchored to the hull, and began working there. It was hard to hear anything in detail, especially over the sound of the engine, but I knew what the plan was. We had discussed a few ideas for retrieving the sampler, once we had firmly ruled out thrusting away from the planet. Grace had suggested one large spool to wind the chain back up, but I couldn't make one large enough to house that much chain. I had briefly toyed with the notion of a sampler that could climb the chain, and spent a while planning potential designs. But there was too much risk of failure. If something went wrong, it would be stuck on the chain and we would need to find some other way of getting it back up to us.

So instead, I had made the winch. The chain was extremely unlikely to come apart on its own, but the design of the links made it very easy to take apart on purpose. That's what the winch was designed to do; pull in a link, rotate it to remove it from the chain, and eject it. The links would burn up harmlessly in the atmosphere, and we wouldn't have to worry about storing the chain or getting separate lines tangled together.

Presumably at that moment, Grace was wedging the winch underneath the chain and activating it. I wished it would talk more about what it was doing, waiting to know what was happening was agonising.

"The winch works. " Grace finally reported.

"Happy." I said. All according to plan. No reason to be terrified of anything. "When winch get to link 216, you increase speed." At its current speed, it would take the winch about thirty hours to pull up the entire chain. That was too long, both for Grace to be awake and for us to be in this very precarious position. The winch's maximum speed was much, much faster, but I wanted to begin slowly to ensure the mechanisms were working as expected. We only had one chance at this, We we’re taking every precaution to ensure it worked.

After a little while Grace said " All good. At least 216 links now. "

"Increase speed." I told it. I could vaguely hear the sound of it pressing down on the lever which would do just that.

"The winch is at maximum speed. All is good. "

"Happy.” I stifled the anxious humming that tried to come out of me. Nothing had gone obviously wrong yet, and weirdly that made me more nervous. It felt like something should be going wrong, even though I really didn't want it to. The longer I waited for it, the bigger it felt like it would be. Obviously that was ridiculous, but knowing that didn’t stop me worrying.

We were both quiet for a while, waiting for the winch to do its work. Even at maximum speed, it was still 10 kilometres of chain. It would take a little while to pull it up. On my console panel I could hear the signal from the probe, getting steadily stronger as it approached.

"Sample device radio signal strong," I reported, "Getting closer. Be ready." The probe could not be allowed to hit the winch at its current speed. If that happened, the impact would tear apart the probe, and probably destroy the winch too, and we would be right back where we started. Except this time we wouldn't have enough xenonite to make the chain we needed. That meant Grace had to be ready to slow down the winch before the probe reached it.

"I'm ready " Grace assured me.

"Be very ready."

"I am very ready. Be calm. "

"Am calm. You be calm."

" No YOU be cal- wait. I see the sampler! " I wriggled and fidgeted, listening as carefully as I could for what was happening. I would have demanded more updates from Grace, but I really didn't want to distract it right now. If this went wrong, I had absolutely no idea what our next steps would be. They would probably involve a lot of screaming, whatever they were.

Grace pulled the lever, slowly and steadily decreasing the speed of the winch, until finally I could hear it in its fully stopped position. Grace moved around again, hopefully retrieving our sample. Finally, when it seemed safe enough, I gave into the temptation to ask:

"Status?"

"I have the sampler. Returning. " Relief washed over me.

"Amaze! Happy happy happy!"

"Don't be happy until I'm inside! "

"Understand" I could see its point, but it was hard to contain my excitement. It had the sample! At that very moment its fleshy hands might hold the answer to saving our stars, and billions of lives. If the predator was in there. If it wasn't in there... I decided to assume the predator was in there for the time being. I didn't think I could cope with the idea of the alternative just then.

Grace started back towards the airlock, and it turned out that it was right. It was too soon to celebrate. The entire ship shuddered, so suddenly and violently that I almost let go of the handholds in surprise. I heard Grace fall to the hull, and for a terrifying moment wondered if it was going to slide off the ship. But it managed to catch itself in time.

"What the heck was that? " It asked. There was a tone in its voice I hadn't heard before. From context I could guess that it was alarmed. I was alarmed, and I also had no idea what had happened. On the screen watcher's readout I could see that Grace's screens were cycling between colours, with large text displayed on them, but I had no idea what information they were trying to convey.

"I not know. Ship move. Sudden." Just as I finished saying that another shudder ran through the ship. This time it kept going. The gravity in the ship had shifted, some new force pulling us in a slightly different direction.

" We're thrusting in the wrong direction! " Grace yelled. Its voice was strained. I had never heard Grace afraid before. Concerned, yes. Also stressed, irritated, upset, and all manner of other things. But I was pretty sure this was what Grace being afraid sounded like.

"Get inside!" I yelled, "Fast fast fast!"

The noise from the ship made it difficult to track Grace's position. It was moving quickly, too quickly to be using its tethers. It if slipped off the hull now, it was going to die. But the hull was not safe right now, and I wanted it back inside as quickly as possible. I felt completely helpless, doing nothing while I waited to see if it would make it back alive.

The ship shook again, and I couldn't hear Grace at all now. There was just too much noise. I wanted to call out to it, but if I distracted it now it might slip and fall. Instead I clung desperately to my own handholds, and hoped.

It seemed like an eternity before I heard the glorious sound of Grace falling face-first into the airlock. I didn't think its face was supposed to take that kind of impact. I wasn't sure the suit was either. But it managed to close the exterior door and cycle the airlock, so it couldn't have been too badly injured. A few moments later it was scrambling into the control room, the space suit left behind in the airlock. I was relieved, but also still terrified. Something was wrong with the ship, and until we fixed it we were both still in a lot of danger.

"Screens flash many colours!" I shouted, hoping it could hear me over the noise. I moved the screen watcher around, hoping anything might provide more information. A horrible groaning sound started all around us, adding to the din. A new wave of terror washed over me. The hull was bending. This was really, really bad.

"Where's that noise coming from? " Grace asked, as it dropped into its control seat. It didn't bother strapping in.

"All around. But loudest at starboard dormitory wall segment. It bending inward!"

Something's tearing the ship apart! Got to be the gravity. "

"Agree." Everything was loud. Everything was screaming. I was so scared I could barely process it. I had been afraid of a lot of things since beginning this journey, but I had never been in such immediate danger before. We needed to go. "We have sampler. We leave now."

"Yeah, let's get out of here. " Grace agreed. It adjusted its controls and the engines came on at their full force. It wasn't bringing us directly away from the planet, just speeding us to bring us into orbital trajectory. We had been stable at that speed for over four cycles, so it should be safe. But the ship was not flying smoothly. I could feel the way it was shifting around, the floor tilting as the ship tried to tip forwards.

"Something's wrong. " Grace said " She's fighting me. "

"Engine damage? Much heat from Adrian." If it was a problem with the engine, maybe I could fix it. Or at least direct Grace in fixing it.

"Maybe, " Grace said, looking at its screens. Maybe there was useful information there, but I was distracted by new sounds from the hull. I really didn't like those sounds.

"Hull bending in big room below dormitory." I told Grace.

"What? There's no room below- oh " I've never learnt the exact layout of Grace's ship, but I could make an educated guess at what the large tanks at the back were for, especially since they still contained some liquid. The hull was bending around Grace's fuel tanks. That could not be good.

"Turn off engines?" I suggested. Using the fuel while the tanks were compromised seemed risky.

"We're going too slow. We'll fall into the atmosphere. "

"Understand. Hope."

"Hope. " Grace agreed. That was really all we could do. If we stopped now, we'd die in the atmosphere. If the fuel tanks got too compromised before we finished, we'd also die. Our lives were at the mercy of physics, and there was nothing we could do alter the outcome.

The wait was excruciating. Even with Astrophage powered engines we couldn't immediately jump to orbital velocity. The kind of power that would require would probably destroy the ship, and almost certainly kill both of us. For the next ten minutes, Grace and I waited and listened in tense silence as the hull groaned and distorted around us. I wished I could hold Grace's hand. I wished I'd brought Adrian's rock to the control room with me. I wished I was back on my ship in orbit around Tau Ceti, where things weren't good but they were at least stable.

I didn't mean that. I wouldn't ever mean that. But I was very scared.

Finally, finally, Grace said: "Velocity is good. Stopping engines. " The relief in its voice was obvious, even to me. I felt it too. It was a shame that it didn't last very long. Grace turned off the engines, and dropped back into its chair. It dropped back. We were in orbit, and the engines were shut down. Nothing should be able to drop.

Grace seemed to realise this too. It held up its arms, and when it relaxed they fell back down onto the chair.

"Uh... "

"Gravity still here . " I said. I wanted to scream. Why couldn't this just be over. Grace checked its screens, but didn't seem to find anything helpful on them. It repeated the test with its arms, and the same thing happened again, falling at an angle. I tried it with one of my own arms, feeling the strange direction of the gravity.

"Adrian gravity?" I asked

"No, we're in orbit. "

"Spin drive?" Admittedly that was a silly question. Grace would probably have noticed if it hadn't turned its spin drive off. But I was feeling a little panicked, and grasping desperately for an answer. Grace gestured at its screen.

"No, it's offline. Zero thrust. " It let its arm fall again. This time it hit the chair significantly harder, and it yelped in pain. Then it did it again. It was falling a lot faster now.

"Gravity increasing." I observed. I could feel it too. We were well above Grace's gravity, and nearing my own.

"This doesn't make any sense! " Grace's voice was strained again, and I thought it was beginning to panic. That wasn't good. Grace was in control of the ship, it needed to be able to use its brain right now. "Our velocity is increasing! "

"Engines on. Only explanation!"

"Can't be. The spin drives are off. There's nothing to accelerate us! " But the pull was still increasing. We had shot past Erid's gravity now, and it was still getting stronger.

"Force increasing." I said.

"Yes. " Grace didn't sound good. Its breathing was shallower and more laboured. I didn't think its body was designed to withstand this kind of force. Its ribs were struggling to move under their own weight. Human bodies needed oxygen, I remembered. Its brain would die without it.

It reached forward, fighting the pull of gravity to interact with its screens. I couldn't do anything but watch as it struggled. It swiped and tapped across the screen, until it stopped to look at something more closely.

"There's a hole in the ship... " It said, fighting to get the words out. That sounded bad. It sounded pretty catastrophic, honestly. The panic was getting to me too now, and I was too overwhelmed to figure out how that had happened. But Grace stayed calm enough to keep searching for information. " Confirmed. Hull breach. Port fuel tank. "

"Why thrust?" I asked, although I was less interested in that than I was in how we could make it stop. But I knew the why might lead to an answer to the how.

"Oh crap! " Grace said, realising something, " The Astrophage in the fuel bay! It's exposed to space! It can see Adrian! my fuel is migrating to breed. "

Oh. Oh no. "Bad bad bad" I squeaked, discovering a whole new level of understatement. The Astrophage exposed to Adrian were all leaping out of the ship to migrate, generating a tremendous amount of thrust behind them. That thrust was pushing the ship in the opposite direction. We probably should have been vaporised by the infrared they generated to move, but evidently there was enough Astrophage behind the ones migrating at the front to absorb that energy.

That couldn't keep up forever. And in the meantime, they were creating more and more thrust as each freshly exposed layer of Astrophage departed. Distantly I wondered which would kill us first; the thrust, or the final layer of Astrophage reducing the ship to a fine mist? I really wasn't keen to find out.

Grace reached out again, painfully slowly.

" Throwing... away... bad... fuel bay. " It wheezed.

"Yes yes yes," I said, desperate for this to stop. It tapped the screen, and the acceleration jerked suddenly in a different direction. The force was so strong that I lost my grip, slamming painfully into the side of the bulb. The vibration made it feel like there was noise screaming at me from every direction at once. I scrambled to grab the handholds again, dropping the screen watcher so that I could hold on with all five hands. There was a nasty sounding crack as it hit the floor, but I didn't have time to worry about it. I could repair it if we survived it.

The hull groaned again. "Thrust continues" I said. I felt dizzy from the impact, my arms hurt, but I didn't dare let go. Grace didn't respond. Its ribs were barely moving now. It reached again, agonisingly slowly as it fought to move. With all its strength it managed to tap the screen again.

The world devolved into chaos. The direction of the force changed again, and I was ripped away from my handholds. I slammed into the wall much, much harder than before. There was absolutely, mind numbing agony as my carapace cracked from the force. Instinctively I curled up as I was bounced around the bulb. Each impact made my body scream with pain, but there was no further damage. It took a minute for me to be catch one of the handholds, bringing myself to a stop. The gravity was working in almost the opposite direction now, pressing me towards the front of the room. There was still far, far too much force. It was almost too much even for me, and I could only imagine what it must be like for Grace.

And then Grace's chair broke. The support holding it snapped, and it was thrown forward on top of Grace . Through the pain in my carapace and the cacophony of the ship I could hear its desperate wheezing as it tried to inflate its lungs, but it couldn't do it. The chair was pressing down on it too hard.

It was going to die.

I barely had a moment to process all of that before my body was in motion, throwing itself down my tunnels.

There were sensible and tactical reasons why Grace should survive instead of me. I didn't know how to pilot the Hail Mary, I didn't understand how any of its thinking machines worked or how I could even interface with them. Without a pilot we would eventually crash into the planet, and even if we didn't I would be stranded in space with no way back to my vessel.

Beyond that, Grace was a scientist, and I was only an engineer. We had a sample now, but even if I could retrieve it from the airlock I wouldn't know how to examine it, wouldn't know how to study these life forms. Grace's ship was full of scientific equipment that only it knew how to use, and Grace would be able to understand and draw conclusions that I could not.

There were a lot of reasons Grace should survive. And as I hurtled towards the dormitory, toward the airlock that would bring me into its side of the ship, I didn't think of a single one of them. Because when I heard it fall, when I heard it trapped under the seat and the air being crushed out of it, there was only one thing that I could do. I lost 22 crew mates, 22 good, brave, smart people in that terrible trip from my world to Tau Ceti. I couldn't do it again. I couldn't watch my friend die again.

I practically fell into the dormitory, hurrying towards the airlock. The room was in chaos, with items randomly thrown around the place. Some things were definitely broken, but I didn't have time to think about them. I clambered into the airlock and then hesitated, just for a moment, with my hand on the atmospheric controls.

I wasn't going to survive this. I didn't know what being in Grace's atmosphere would do to my body, but it probably wasn't something that I would be able to recover from. If I was lucky I would have enough time to make it to Grace before I collapsed. It was probably going to hurt. It was definitely going to kill me. I was afraid to die.

I pulled down the lever, and the airlock cycled.

I mentioned before that there was very little temperature variance on Erid. There are no seasons, no climates, no change from "night" to "day". I could sense different temperatures, but I had very little experience in extreme changes. So when Grace's atmosphere washed over me, I didn't even really register it as "cold" initially. It was a temperature so far below anything my body evolved to recognise that my nerves couldn't make sense of it. I made it as far as opening the door, and stumbling a few steps through the dormitory, before they settled on interpreting the sensation as agony. It was so cold that it paradoxically felt like I was burning.

Except for the radiator, which I realised as I crossed the lab might actually be burning. There was definitely something happening there, the air moving across my radiator felt wrong, and thick. Oxygen, I thought. Terrible idea to have that on a spaceship.

When I reached the control room I could barely make sense of what room around me. I was trying to listen but my entire carapace was an unending scream of pain. I had to focus. If I couldn't find Grace then I would be dying in this room for nothing, and both of our planets would die too.

There. It was right where I'd left it, trapped under the chair. I couldn't even tell it if was breathing at all anymore. I pushed through the distractions- the pain, the hull still groaning around us, the fear, all of it- and focused on this one simple task. At some point during our flight Grace had strapped itself into the chair, and I used my fingers to slash through the fastenings. With all the strength I had left, I grabbed the chair and pulled it off of its unmoving form. Grace inhaled loudly, which quickly devolved into ugly spluttering noises. But it was alive.

It was alive.

I dropped the chair down next to us. It might have broken something, I wasn't paying attention. And Grace was trying to say something, but the world around me was beginning to fade. I was so, so tired. Maybe this was just like going to sleep, I thought. Sleep was frightening, but it was a familiar kind of frightening. And I didn't have to do it alone. Grace was here to watch me, and now its upper body was upright, its head facing down at me. I wasn’t standing anymore. I wasn't sure when that had happened.

I really wanted to reach out and take its hand. It would be nice to fall asleep holding someone's hand again. But my body was too hot, and I didn't want to hurt it. Humans were so very delicate. It was still trying to talk. I should say something, I thought.

"Save... Earth..." I said weakly, as the world grew fainter around me, “Save... Erid..." There was more I wanted to say. Things like "Thank you", and "I'm sorry" and “Please, please don’t die”. But the words were too far away now. Everything was so far away. Even the pain felt distant.

It's okay, I told myself. It would all be okay. The world was going away, but it's okay. I'm just going to sleep. And maybe Adrian will be there, when I wake up.

Chapter Text

Waking up after dying was a strange experience.

It also hurt .

The pain was the first thing that I was aware of. Every inch of me ached, from the tips of my fingers to my soft, fleshy innards. Waking up felt like dragging myself through a thick fog made of acid.

It didn't recede, exactly, but I slowly became of aware of things besides the pain. Where was I? Presumably I was back in my own atmosphere, since I didn't seem to be on fire anymore. Even if it did kind of feel like it. Everything sounded fuzzy and indistinct. I really hoped I hadn't permanently damaged my hearing.

I was resting on the floor. So there was Gravity, although it felt much weaker now. I was also no longer rattling around and bouncing off the walls, which was nice. Everything seemed much calmer than it had been before. Grace must have managed to get the ship under control.

Grace.

I forced myself to focus, to listen to the room around me. I was in the dormitory. Actually, I was in the airlock in the dormitory. Everything was still a mess, there were bits scattered and broken all over the room. And the walls were covered in something, some grimy- wait.

Listening more closely, that really sounded like scabbing residue. But that should not be on the outside of me.

Damage to organs is relatively rare for Eridians, since we are very well protected inside the carapace. But when it does happen, the body coats them in a powdery gunk that covers them while they heal. The gunk is full of... something. I don't actually know the details, but it's important for healing, and it prevents bacteria from infecting the wounds. Infections are a very serious problem. Even with medical intervention the fatality rate for them was very high. So it was a little alarming to hear that it had somehow been removed.

I wasn't dead, so presumably I had had enough time to heal before it all ended up on the walls. That did not explain how or why that had happened though. But that mystery could wait for a few minutes. I moved my attention away from the residue, and listened to the room again. It was hard, and my carapace ached so much.

But there was Grace. It was lying in its nest, safe and alive. The relief I felt was so intense I almost passed out again. I didn't think it was sleeping, it was moving around a lot more than usually would, even during its more upsetting sleeps. Its breathing was laboured, and it made a lot of small noises as it writhed. I thought that maybe it wasn't very well. But it was alive.

With great effort I lifted one hand to the wall of the airlock, and tapped gently. Grace made a sound, but didn't turn around to face me. I tapped again, and just doing that much was exhausting. My body was not right. But Grace finally turned over at least. For a moment there was no other reaction, and I wondered if it was struggling as much as I was with focusing. I would have tried to wave, but. Ow. Then Grace took in a sharp breath.

" Rocky! " It rolled off its nest, falling gently to the floor. The gravity must be very low, even for Grace. That spoke poorly of my current condition; If I couldn't handle moving around in lower-than-Earth gravity I must be in very bad shape indeed. Grace scrambled off the floor, pressing its hands to the airlock. " Rocky, buddy! Are you okay? " There was something wrong with its voice. It had a kind of scratchy quality to it that I didn't recognise.

"Sick" I said, my own voice coming out very quietly.

"" I don't understand. Speak louder. " Human hearing is terrible. I didn't want to be louder, the vibrations of my voice did not feel very good. Everything was so jarring. But I raised my voice anyway.

"Sick." I said again.

" Yeah, you're sick. You came into my air. Of course you're sick! You almost died! " Almost being the operative word. I was still processing the fact that I was alive, even if I was in a tremendous amount of pain. I tried to stand, but my arms couldn't support the weight of my own body. That really was not promising.

"How I return here?"

" I moved you. " Grace said. That couldn't have been easy. Even in Zero G Grace had struggled with shifting my ball around. And the ball hadn't been over 200 °C on the outside. I'm fairly sure direct contact with my carapace would cause serious and possibly permanent damage to its skin. But that wasn't what concerned me right then. The thing that concerned me was the fact that I could hear in the controls on Grace's side of the airlock, and they were completely broken. Thinking back, I vaguely remembered that they had been broken when I'd passed through before. Which meant that the only way for it to have set the airlock to my atmosphere was to have pulled the emergency release valve inside the airlock.

"You touch me air?" I asked it.

" A little, yeah. " I listened more closely to Grace. It normally wore clothes that covered its arm, but its upper body was bare at the moment. Except the left arm, which had cloth wrapped around a significant portion of it. The skin underneath sounded wrong. I pointed at the arm.

"Skin on arm is not smooth. Damage?" Grace's face got more folded.

" Yeah. But I'll be fine. " I really hoped that was true. Grace's body language was still difficult for me to understand, but it seemed like it was in pain. I knew that Human skin was covered in nerve endings, like the outside of my body. Burning them couldn't be a pleasant experience. But it had done it anyway, to try and help me. I was still alive because it had done that. I was alive.

"You damage self to save me. Thank."

" You did the same thing. Is your radiator organ okay? You were on fire and got full of soot and oxides. " Ah, so it had been on fire. Even though I'd sort of known that I didn't like hearing it. My radiator felt raw, and sensitive. It was obviously hurt, but it was still functioning. The air moving across it didn't feel pleasant, but it was tolerable. And that reminded me of my other question.

"It healing" I said, and pointed at the scabbing residue spread over the walls. "This come from inside me?"

" Yes " Grace confirmed

"How it leave me?"

Grace pointed to a box that had been affixed to the wall at some point while I as unconscious. " I made a device to blow air at you. I aimed at your radiator vents and all that nasty stuff came out. "

Okay. Okay. So Grace had done that. Okay. A lot was going through my mind at that moment. On one hand, I was impressed that Grace had managed to put that together. It wasn't very good with engineering, but it seemed like it had done a good job. It had even managed to drill into the xenonite. On the other hand, why would it do that.

I tried to think about it from Grace's perspective. It had said my radiator was full of soot and oxides. If Grace had been full of soot and oxides I probably would have assumed that was bad for it. It didn't know much about Eridian biology, so it must not have realised that the scabbing residue was supposed to be there. The difference between the scabbing residue and soot seemed obvious to me, but maybe it had appeared similar to Grace's light sense.

"How long was that stuff inside me?" I asked. Grace thought about it for a moment.

" About... two days. " Okay, probably about 42-54 hours. Long enough for the wounds to close over. Just enough. But if it had done that a few hours earlier I probably would have gotten an infection and died. That was cutting it pretty close. So Grace had seriously injured itself getting me back into my environment, and the proceeded to almost kill me anyway while trying to help. I should probably have been horrified by that, but for some reason in the moment it struck me as kind of funny. I wondered if Grace would find it funny.

"You almost kill me." I told it. That seemed to confuse it, so I explained about the healing process, and the scabbing residue.

Grace did not find it funny.

" I'm so sorry, I was trying to help. "

"It okay," I assured it, "If you did earlier I die. But I heal enough before you do it. Removing help a little. Thank." That was kind of true. Looking at the amount of scabbing there was, it probably would have started causing a problem with the radiator if left to block it much longer. Though a doctor would have left it a while longer before intervening to remove it. Grace was still upset.

" Sorry " It said again. It sounded miserable. I decided I wasn't going to stand for that. Not now, after everything.

"No say sorry." I told it firmly, "You save me when you put me in here. Thank thank thank." Yet again I found myself struggling against the language barrier, and it was very frustrating. Thanks were inadequate for what I wanted to say. The moment I had pulled that lever in the airlock I had accepted that I was going to die. that I would never see my world, or my family again. And Grace had hurt itself, possibly quite badly, to give that chance back to me.

I should really teach it more of my words, I thought. Enough words so that I could tell it I would be grateful forever. That I was unfathomably lucky to have found a friend as loyal and as brave as Grace in this empty, lonely place.

Maybe I would. Tomorrow. When I wasn't so exhausted. I tried to pull myself up to my feet again, but it was still too much effort. My carapace sunk back down to the floor. Tomorrow sounded good.

"I am weak," I told Grace, "I will heal." It backed away from the airlock, sitting down on the edge of its nest.

" Would you be more comfortable in Zero G? I can turn off the centrifuge. "

"No. Gravity help heal." I didn't want to deal with floating around in this state. If I bumped into anything it was going to hurt. Besides, the gravity was comforting. I pulled my arms up underneath me, so my carapace was resting on top of them. It was such a small thing, and I had missed it so much when I had been alone. The wonderful luxury of sleeping in a familiar posture. "Sample container is safe?" I asked.

" Yes, it's in the lab now. I made an Adrian environment in a sealed container and put some Astrophage in along with the sample container. I'll see how it's doing in a bit. "

"Good. Human light sense very useful."

" Thanks. But my Human brain wasn't as useful. I don't have a way to get the sample out of the container. "

I tilted my carapace questioningly. "You seal sample and can no access sample?"

" Yes. "

"Usually you not stupid. Why stupid?" It occurred to me immediately after saying it that that was probably not a socially accepted way to ask that, on my planet or Grace's. In my defense I was in so much pain, and access to the sample was a pretty important thing to overlook like that. Grace didn't admonish me for it anyway.

" Humans are stupid when we need to sleep. And when we take medicine to stop pain. I'm tired and drʌɡd right now. " Grace had said before that Humans needed to sleep for their brains to work properly. There was nothing I could do about Grace's pain, but if it needed more sleep there was a simple solution for that.

"You should sleep." I told it. Grace stood from its nest, wobbling slightly as it did so.

" I will in a bit. But first I have to stabilise our orbit. Our apogee and perigee are... well, it's not a good orbit. "

"Adjust orbit while stupid." I said dryly. "Good plan."

Grace laughed weakly. "New word: ' Sarcasm '. You say opposite of true meaning to make point. 'Sarcasm' ."

***

It took a little more convincing, but Grace finally agreed to sleep before it tried to adjust our orbit. Its robot gave it some more medication, and it fell asleep almost as soon as it lay down. It must have been very tired. For a while I just sat and watched it sleep. It was comforting, watching it rest in relative safety. I still couldn't quite believe we were both alive after everything.

After an hour or so I tried getting up again. I took it slowly, testing the strength of my arms before fully raising myself up. I wobbled a little, but I didn't think I was going to collapse again. With some effort I opened the door and left the airlock, returning fully to my enclosure.

The room was an absolute mess. The storage boxes had been thrown around, some of them spilling their contents. My neatly organised workbench was lying on its side, looking slightly dented in places. Had it been that bad before I'd collapsed in the control room? I couldn't remember, I'd been panicking and in a hurry.

I spent the next couple of hours tidying up. It was surprisingly soothing, taking the catastrophic mess and returning it to something orderly. It was also painful, because everything was still painful. But moving around was helping me feel more like my normal self. I repacked all the boxes, and stacked them neatly against the wall, righted the workbench, organised my tools and materials. By the end you almost wouldn't have been able to tell the room had been through a catastrophe that almost killed both of us.

Adrian's rock was scattered among the debris. Remarkably it had somehow made it through the incident without taking any further damage. If I was more superstitious I would take that as a good omen. I just hoped the worst of it was behind us now. We had the sample, and if the predator was in there- it had to be, it had to be in there- then we would have what we needed to stop Astrophage. We just had to keep moving.

Once I was done with tidying, and I was sure I could handle the ladder, I took a trip up to the lab to see Grace's sample container. I could still hear Grace sleeping from the lab, which was promising. If my hearing was improving then maybe I hadn't permanently damaged it. Only time would tell if it would make a full recovery.

It wasn't actually a very complicated problem. The sample container was inside a larger vacuum chamber, along with a swab that presumably held the Astrophage that Grace  had mentioned. The chamber had cracks along the sides that Grace had clearly patched up. It would have been too much to hope that the lab equipment hadn't been damaged during the incident. I just hoped that nothing critical to our success had been irreparably broken.

The chamber had presumably been filled with an Adrian atmosphere. The sampler, doing its job as intended, had opened when it reached the correct pressure, releasing the sample into the chamber. It was good to know that I had at least done that part correctly.

In hindsight, I had been unimaginably stupid. The Hail Mary was Grace's ship, so I had defaulted to its knowledge of its systems. But Grace was not an engineer. Everything it knew about the ship was stored on its thinking machines, and having access to that knowledge did not mean that it had any inherent understanding of it. I was the one who was supposed to understand how these systems worked. I should have realised the risks of the cooling system being overwhelmed. The thinking machines had even tried to warn us, but we had both been so desperate for the sample.

Astrophage was, as near as I could tell, a perfect heat absorption system. Nothing that was done to it changed its temperature, not even being exposed to IR light from other Astrophage. But even with the Astrophage conduits built through it, the hull was still mostly aluminium. The heat still had to conduct through it before being absorbed by the Astrophage. That heat had reached melting temperatures before the cooling system could do anything about it, and I should have realised that . It was nothing to do with advanced alien technology, it was a simple process of heat transferal.

I didn't feel up to pacing yet, but I scratched a finger against a wall to try burn off my agitated energy. Being angry at myself served no real purpose here. It was done now, we just had to make the best of it. We had the sample, and I just needed to get Grace's swab out of the box. That wasn't so hard, the basic idea of what we'd need was already forming in my mind.

After I'd inspected the latching mechanism on the vacuum chamber, and double checked the size of it, I headed back to the dormitory to begin work. Grace had barely moved while I was gone. Well, barely for Grace. Obviously an Eridian wouldn't move at all, but Grace tended to turn over during various phases of its sleep. Humans sleep in phases, according to Grace. Some of them were "lighter", and easier to wake from, and that's also when a lot of the moving around happened. I thought it must be sleeping quite deeply right then. That was probably good. If it needed sleep to recover, than sleeping deeply probably helped that process.

I spent the rest of its sleep cycle at my workbench, quietly working on a box large enough to contain Grace's vacuum chamber. Some time during this, the robot arms reached down from the ceiling and started doing something to Grace's arm. It made me nervous, and I stopped what I was doing to watch it. The Humans had made that robot to look after the Hail Mary's crew while they slept on the trip here. The robot had failed. I didn't want it to fail while looking after Grace.

Thankfully nothing alarming happened. The robot unwound the cloth from around Grace's arm, and sprayed it with some kind of liquid before wrapping it in a new cloth. Grace barely stirred through the process. It must have been very deeply asleep. But it was still breathing, and didn't seem to be in distress. I could only assume that meant it was alright. After watching a few more minutes, I forced myself to get back to work.

It was another couple of hours before I finally heard Grace's breathing change, and its head turn in my direction. "You are awake?" I asked it.

" Yeah. " It replied. Its voice still didn't sound quite right to me. I wondered if something was wrong with the part of it that produced the noise. " How are you feeling? Are you healing? "

I wiggled a finger. "Much more heal needed. But some heal complete. Cannot move much."

Grace rested its head back in the nest. " Same "

"Robot arms do something to you arm while you sleep." I informed it. It pointed to the cloth covering it arm.

" It changed the cloth. It's important for human healing to change the cloth. What's that? " It didn't gesture, but I assumed it was referring to my current project.

"I go to lab to see device that store Adrian life. I make device now to collect sample from inside and not let you air in." I lifted up the new box, made from xenonite. "Put you vacuum chamber in this. Close this. This make Adrian air inside." I opened the top, and pointed to a road which was attached to some control mechanisms on the exterior of the box. "Control these from outside. Gather sample. Seal you device. Open my device. Have sample. Do Human science with sample."

" Smart ." Grace said, " Thanks. " It was quiet for a for minute while it watched me work. This wasn't a complicated device, but I needed the controls to allow Grace to easily manipulate the robot hands on the inside. The work I did trying to make Space Catan accessible to Grace turned out to be quite useful for this. I had already put a lot of thought into how this sort of system would work. My mentor had always told me that no engineering work was frivolous; Every project, no matter how small, teaches you important things about the craft. I really needed to visit it when I returned to Erid, and thank it for everything it taught me.

Grace requested some liquid from its computer, and the robot handed it to it in an open container. It always does that when there's gravity. When there's no gravity it gives it to it in a pouch. I wondered if the open container was culturally significant somehow, since there was no real reason not to just use a pouch every time. Grace ingested the liquid slowly, being careful not to handle it with its injured arm.

" Hey, " It said, " how come you and I hear the same sounds? " This was something we did occasionally. One of us would ask a question, and we would swap theories about it. Normally I wouldn't talk to Grace while it was eating, but I thought it could probably do with a distraction from its pain.

"Useful trait," I said, not pausing my work, "Both evolve. Not surprise."

" Yeah, but why the same frequencies? Why don't you hear much higher frequencies than I can? Or much lower? "

"I do hear much higher frequency and much lower frequency." Human hearing was very limited, in both range and frequency. I had met Eridians before who had comparable hearing to Grace, but it was a fairly rare condition. Even Ayda's hearing had been far better. But Grace had evolved to depend on its light sense, and apparently that left it with far less need for sensitive hearing.

" Okay, but why is there overlap? " Grace persisted, "Why don't you and I hear completely different frequency ranges? "

I put one of my tools down, still working with two of my hands, and scraped a finger gently across the workbench. "You hear this?"

" Yes ."

"That is sound of predator approaching you. That is sound of prey running away. Sound of object touching object very important. Evolve to hear."

" Ah! Yes. " Grace agreed. Regardless of the conditions of the world that you evolved on, object interaction took place in a fairly limited range of sound frequencies. Someone running on Erid might have a different number of limbs to someone on Earth, but the sound of them striking the ground would be very similar.

"Better question. Why we think same speed?"

Grace set down its liquid container, and lay down on its side facing me. "We don't think at the same speed. You do maths way faster than I can. And you can remember things perfectly. Humans can't do that. Eridians are smarter."

I thought about my mentor. It hadn't bee able to remember things, or hold numbers in its mind without help. Neither of which had impaired its ability to think.

"Maths is not thinking. Maths is procedure. Memory is not thinking. Memory is storage. Thinking is thinking. Problem, solution. You and me think same speed. Why?"

" Hmm. " Grace was quiet for a moment while it thought about it. " Well... I have a theory for why we're about the same intelligence. Maybe. "

"Explain."

" Intelligence evolves to give us an advantage over the other animals on our planet. But evolution is lazy. Once a problem is solved, the trait stops evolving. So you and me, we're both just intelligent enough to be smarter than our planet's other animals. "

"We are much much smarter than animals." Well, Eridians were. I actually had no idea what the other animals on Earth were like, but none of them had sent their own missions to Tau Ceti.

" We're as smart as evolution made us. So we're the minimum intelligence we needed to ensure we can dominate our planets. "

I thought about that for a moment. "I accept this. Still not explain why Earth intelligence evolve same level as Erid intelligence."

" Our intelligence is based on the animals' intelligences. So what is animal intelligence based on? How smart do animals have to be? "

"Smart enough to identify threat or prey in time to act."

" Yes, exactly! But how long is that time? How long does an animal have to react? How long will the threat or prey take to kill the animal or escape? I think it's based on gravity. "

"Gravity?" I set down my tool to focus on Grace. i was curious about where it was going with this.

" Yeah! Think about it. Gravity is what determines how fast an animal can run. Higher gravity, more time spent in contact with the ground. Faster movement. I think animal intelligence, ultimately, has to be faster than gravity. "

"Interesting theory. But Erid have double Earth gravity. You and I same intelligence."

" I bet our gravities are so close to the same, astronomically, that the intelligence needed is almost the same. If we met a creature from a planet with one one-hundredth of Earth's gravity, I bet it would seem pretty stupid to us. "

"Possible." I conceded. It was an interesting thought. But barring the discovery of more life forms from worlds with extremely different gravity, it didn't seem like we were going to get any confirmation one way or the other. "Another similarity: You and me both willing to die for our people. Why? Evolution hate death."

" It's good for the species. " Grace said, " A self-sacrifice instinct makes the species as a whole more likely to continue. "

"Not all Eridians willing to die for others."

Grace laughed. " Not all Humans either. "

"You and me are good people."

" Yeah, " Grace smiled gently, " I suppose we are. "

***

The next couple of cycles were very difficult.

My condition was definitely improving, but everything still hurt a lot. And Grace was not fairing much better. Its left arm still functioned, but it couldn't do as much with it as it could before. Everything it did with it hurt, and it required regular care to keep clean. Grace said that burns were a high risk for infections, and I found myself worrying about that constantly. Infections were bad, bad news. And then there was the issue of its medication.

I had some... harsh things to say when I realised Grace had left our sample sitting at room temperature for two days. We had both almost died retrieving that sample, so I was naturally a little worked up over Grace being so careless with it. A lot of life is very sensitive to temperature, and we had no way of knowing if the predator could survive any amount of time in a room 70 degrees warmer than its natural environment.

It wasn't completely Grace's fault. It was exhausted, and confused because of the medication. But I couldn't trust it to do its science when it was that confused. So I told it wasn't going to give it the retrieval device until it had been off its medication for at least three of its cycles.

Grace seemed to understand, but that didn't make the process any less terrible. For the first couple of its cycles it simply could not function without the medication at all. It didn't matter if the medicine made it stupid if the pain also rendered it both stupid and incapable of basic daily activities. I made sure to monitor Grace closely during these days, I didn't want it to hurt itself or damage something while it was under the influence of the medication. It spent most of this time tidying up and reorganising everything, taking inventory of what supplies had survived the catastrophe. Thankfully a lot of the scientific equipment still worked, including the microscope. That was a relief.

It would do these tasks until the pain got too severe, even with the help of the medication, and then it would lie down for a while.

The first cycle without medication was the worst. It spent the entire day in its nest, writhing and groaning. I suggested that maybe this was too soon to stop the medication, but Grace was determined to get through the cycle without it. I knew it was impatient to get back to its work, and I knew that Earth didn't have very much time, so I didn't push the issue. But I  did spent that day in the dormitory with it, watching over it as it lay in pain.

I managed to get a reasonable amount of work done. There were a few things, like my screen watcher, that had been damaged during the catastrophe and I spent some time repairing them. I even made a replacement for the airlock controls on Grace's side of the dormitory, but had to wait for Grace to feel well enough to install them. The crack in my carapace still throbbed with pain, and I got dizzy if I moved too fast, but I was slowly recovering. And by this point my hearing was almost back to normal, although loud noises were jarring and painful to listen to.

" Hey Rocky ." Grace said quietly, late in its cycle. It really needed to go to sleep, but the pain was making it difficult for it to settle. I was back to working on the controls for Space Catan, since I'd finished my more important work for the time being.

"Yes Grace?"

" Why didn't you ever go back? " The question caught me off guard, and my hands stilled at their work. Grace was still lying on its back, face pointed up at the ceiling. It's left hand clenched and unclenched slowly as it tried to overcome the pain.

"Go back?"

" To Erid. After your crew died. After you couldn't find a solution. Why not go back to Erid, make a new plan? Why stay here alone for so long? "

I had to think about how to answer. It wasn't as though I'd never thought about it. I'd considered the idea a few times, over the years. But it was hard to talk about, especially in our limited vocabulary.

"Was not sure what Erid would do. If I go home, maybe they try send new mission? Not know about radiation. Not know why crew die. If send more people, maybe they die too. Not want another crew to die." And I hadn't wanted to face the loved ones of the dead. I hadn't wanted to tell them that everyone but me had died, and I had failed to find an answer. That I had given up and come home because I was lonely and scared. But I didn't think I could say all of that.

Grace was quiet for a while. I thought that maybe it had finally fallen asleep, before it spoke again.

" How did you do it? How did you keep going all that time, not knowing if you'd ever find an answer? If you'd ever see home again? "

"Could not stop."

" Well, yeah. You had to keep going for the sake of your planet, but still- "

"Not needed to keep going," I interrupted, "Could not stop."

" I don't understand. " Well, I couldn't blame it for that. I'd spent a lot of time trying to understand it myself. I struggled to think of what to say. How could I explain this to someone who barely understood my language, when I wasn't even sure how I would explain it to my closest friends?

But Grace was a friend now. A very, very dear friend, and I found that I wanted it to understand this piece of me. I just needed to find the right words.

"Adrian is orbit around Tau Ceti, yes?"

" Yes...? " Grace responded, clearly confused by the shift in conversation.

"Planet that orbits is fall toward star. But not crash, because planet always miss. Fall, miss, fall, miss. Always always always."

" Yeah, " Grace said, turning its head to face me finally, " The arc of the fall matches the curvature of the star, so it never makes contact. "

 "Yes. But planet not choose to miss star. Planet is in motion. Object in motion does not stop, unless new force make it stop. No friction in space, no air to make planet slow down, so planet fall fall fall and never stop. Not matter if planet want to escape." My voice dropped. "Not matter if planet want to crash. Planet not have own energy. Planet only have inertia and momentum. So fall fall fall. Always fall. Never stop. No choice."

Grace didn't respond for a while. It just lay on its nest, watching me intently. I felt raw and exposed, like my carapace had just been peeled back and I was waiting for Grace to judge the contents. Then it raised its arm, the undamaged right arm, and reached out so the tips of its fingers rested against the wall of the enclosure. I raised my own fingers to rest in the same place. We were both quiet.

" Sometimes a planet gets impacted by other large objects. " Grace said eventually. " If the new objects gives it enough energy, maybe it escapes its orbit. "

"Yes. Or get too close to star and crash."

" Yeah, maybe. " Grace's said softly. " But we're not dead yet, right? " And bizarrely, that made something inside me settle. It still hurt. But my momentum had shifted now, for better or worse, and I wanted to see where it took me.

"Not dead yet." I agreed.

" I hope it takes us both home ." Grace said, like it could hear my thoughts.

"Same. Same same same."

Chapter Text

" Gathering sample... now. " Grace said. We were back in the lab, with me watching Grace from my tunnel. It had made it through its three cycles without medication, and we were finally retrieving the sample. I was doing my best not to fidget with anticipation. We were moments away from learning if this entire debacle had been worth it, and I was excited and very, very anxious.

I was still keeping a close eye on Grace through the process. Its arm was still obviously bothering it, even if it was more clear headed than it had been. I still ached too, so we were both taking things slowly. Grace seemed to think that it was ready for this task though, and I just had to trust it to assess its own condition. We kept the gravity at half of Earth's, just to make things easier on us.

The retrieval device was working exactly as expected. It had a few valves and pumps to allow Grace to control the atmosphere, and a device for temperature control that should have the sample back down to -51°C. Of course for the sample to be alive right now it would need to be able to survive Grace's temperatures, but I still felt more comfortable bringing it back down to its natural conditions. Inside the box, the vacuum chamber had been opened, exposing the sampler and the swab inside.

Grace used the controls to open and close the grabbers in the box. " Look at me, I'm an Eridian now. "

"Yes. Very Eridian." I said dryly. "Hurry and get sample."

" You're no fun. " Grace complained, but it used the grabbers to reach into the vacuum chamber and retrieve the swab. It rubbed it against a glass slide it had left inside the retrieval device, then returned the swab to the chamber and resealed it. The slide was then inserted into a small xenonite container, to keep it in Adrian atmosphere.

" Okay. That should do it. " Grace adjusted the dials on the retrieval unit, replacing the atmosphere inside with Grace's own. When the pressure had equalised with the lab's, it opened up the retrieval unit and picked up the xenonite container. It might seem like a bit of a convoluted process just to remove something from a box, but it was necessary to keep the sample in its own atmosphere. I felt some of the tension leave me as Grace carried the little container over to the microscope. We finally had the sample in hand, ready for Grace to do some science at it.

"You are certain you can see light so small?" I asked it, scurrying to stay near Grace. I wanted to be close to the science, even though I knew I wouldn't be able to hear whatever Grace's light sense was telling it. It just felt better to be nearby.

" Yes, " Grace reassured me, " Old technology. Very old. " Grace had told me a little bit about how the microscope worked. The device used clear lenses to refract light, which made things appear larger than they actually were in the Human light sense. It wasn't a totally new idea me, Eridians used lenses to focus cameras, but I was still fascinated that they could refract light enough to observe something as miniscule as Astrophage.

Grace placed its eyes by a tube at the top of the machine, and adjusted a dial. " Okay Adrian, what do you have for me? " Grace doesn't always just talk to itself, it sometimes talks to objects, and life forms like Astrophage that aren't aware of its existence. " Lots of life in here. " It said after a moment, "Different kinds. "

"Good. Expected." There had been a lot of life forms in the migration line too, and we'd already suspected there would be a predator at this altitude. I expected that there was an entire ecosystem of bacteria throughout the atmosphere. There might even be multicellular life further down.

That gave me a moment's pause. I hadn't really stopped to consider that before. But if we were related to life on Adrian, as Grace and I suspected, then its biosphere was at least as old as Erid or Earth. There could be animals down there. I wondered if any of them would have noticed us almost dying just above their atmosphere.

Grace flipped a button on its machine, and I made myself focus on the task at hand. " This could take some time, " it said, " Need to see interaction between- whoa! " It quickly brought itself back to the microscope.

"What? What happen?" I asked. Grace didn't answer for a moment, and I wriggled and fidgeted, desperate to know what it was observing.

" Got it! " Grace declared trimphantly, " I found the predator! It ate Astrophage right in front of me! "

"Found!" I shouted, "Isolate!"

" Yes, I'll isolate it ." Grace bent down to search through a supply cabinet.

"Happy happy happy!" I trilled, "Now you name." Grace had grabbed a small item from the supplies, and began bringing it to the microscope.

" I don't follow. "

"Earth culture. You find. You name. What is name of predator?"

" Oh, " Grace considered this for a moment. " Taumoeba, I guess. " Well, I knew what "Tau" meant. That was part of its name for Tau Ceti. I wasn't sure what "moeba" was, but I was sure it had to be something to do with biology.

"Good good. Eridian word is 'Taumoeba'¹." Grace moved on to isolating the "Taumoeba", while I tried to contain my excitement. We had it. It had taken 46 years, and both of us almost dying, but we had the predator. The thing that could save both of our worlds.

It had been a terrible journey, but I was so, so close. I just needed to hang on a little longer.

***

All things considered, I was doing a good job being patient. Maybe I was a little jittery. Maybe I was checking on things more often than was really necessary. But overall, I felt it was an admirable effort.

Science is a very powerful tool, but not a fast one. We had the Taumoeba, but that didn't mean we could just jet off back to our planets with it. First we had to test it, to make sure it was going to work the way we hoped it would. And before that we had to make sure that we had enough of it to experiment on without running out.

We kept the original colony in the retrieval device, maintained at its natural temperature of -51°C. i wanted to keep that one in optimal conditions, because if all the Taumoeba died there was no way for us to collect more of them. At least, no way that wouldn't result in our rather spectacular deaths. Meanwhile I had built a tank for breeding the ones that Grace had isolated from the sample. It was basically just a box with an Adrian atmosphere and some Astrophage inside.

So far there had been no issues. The Taumoeba bred very quickly, and it took very little time for us to achieve an estimated population in the tens of millions. It just didn't feel fast because there was nothing to do during it except wait. But now we had enough that Grace felt confident moving onto the next step.

I was sitting in the tunnel, fidgeting anxiously as I watched Grace setting up the experiment. We knew that Astrophage was a very robust life form. It could survive on stars, in the vacuum of space, and in the atmospheres of at least five different planets. But Taumoeba didn't travel like its prey did. We couldn't know if it would survive in our star systems without testing it.

The experiment consisted of two tanks with valves that allowed Grace to adjust the gas levels inside. At that moment it was recreating the atmosphere of Venus, the planet that Astrophage used for breeding in the Sol star system. The atmosphere was 96.5% carbon dioxide, and 3.5% nitrogen. Just carbon dioxide and nitrogen. Nothing else.

"No have oxygen?" I asked Grace. It was possible that I was still a little on edge after the whole "being on fire" incident. I hadn't enjoyed being on fire, and I was really hoping to avoid doing it again.

" No oxygen. " Grace confirmed.

"Oxygen dangerous."

" I breathe oxygen. It's okay. "

"Can explode."

Grace turned to face me. It was wearing some hard protective covering over its eyes, because Human eyes were very delicate and it was important to protect them when doing science. It lifted the covering away from its eyes to respond. " There's no oxygen in this experiment. Calm down. "

"Yes. Calm." I said. Grace replaced the covering over its eyes and turned back to its work. Admittedly I was being a little ridiculous. Grace's section of the ship was literally filled with oxygen. My tunnel was surrounded by it at that very moment. Even if there was oxygen in the experiment, it wouldn't really change anything. And even if it did, I was protected behind my xenonite walls. But that wouldn't help Grace, who still had to be careful when using its burnt arm.

I reminded myself that Grace was perfectly safe, and so was I. The burns on its arm hadn't even been because of oxygen, that had been pure heat from my own atmosphere. There was no oxygen in the experiment, and the levels that Grace was currently being subjected to were not only fine but also necessary for its survival.

Grace turned a valve to let more gas into the chamber, and I could hear the rush of air in the pipes as the airlock filled with oxygen.

"Again confirm: No oxygen?"

Grace's head whipped around to face me. " It's just carbon dioxide and nitrogen! Only carbon dioxide and nitrogen! Nothing more! Don't ask me again! "

I shrank back from Grace's irritation. "Yes. No ask again. Sorry."

Grace turned back to finish the work on the Venus tank. The pressure inside was very low, only a fraction of a percent of Earth's atmosphere. That meant I couldn't really hear anything inside the tank, but anything interesting would be happening on a scale too small for me to listen to anyway. I knew that there was a slide in there that Grace had coated with Astrophage, and then seeded with Taumoeba. If the Taumoeba survived, they would eat the Astrophage and Grace would be able to tell the difference using its light sense.

" Okay... the chamber has Venus's upper atmosphere duplicated. As good as I can, anyway. "

"Good." I said, "Now Threeworld²."

" What temperature is Threeworld's air at 0.02 atmosphere altitude? "

"Minus 82 degrees of Celsius." I told it. That's not something I would have known prior to the Astrophage crisis, but I had learnt pretty much everything there was to know about the Astrophage breeding planet during the planning phases of the mission. I hadn't known how useful the information would be then, but I was very thankful to have it now. It wasn't as though I had a clever machine I could find the information on.

Grace turned to the second tank, and began filling it with with an approximation of Threeworld's atmosphere. I forced myself to stay calm as the air hissed into the tank. It was just carbon dioxide, nitrogen, and sulphur dioxide. Grace had synthesised that last one itself, from some sulphuric acid it had had in the lab. Grace was very resourceful, and I was lucky to have it here. And there was no oxygen in the experiment. But it was a real relief when it shut off the valves.

" Okay, Threeworld's done. We'll wait an hour and check results "

"We have hope."

" Yes, we have hope. " Grace agreed. " Taumoeba are very sturdy. They can live in a near vacuum, and they seem comfortable in extreme cold. Maybe Venus and Threeworld will be habitable for them. They're good enough for Taumoeba's prey, so why not for Taumoeba? "

I fidgeted in my tunnel, from a mix of nerves and excitement. "Yes. Things are good! All is good."

" Yeah. For once, everything's going great ."

No sooner had Grace said this then its whole body suddenly went tense. Its head swung from side to side, like it was searching for something.

" Okay, " it said, " stay calm. Stay calm. " It didn't sound very calm. Which was alarming because as far as I could tell nothing had happened.

Actually, that wasn't quite true. The ship seemed... quieter.

"Why not be calm?" I asked, trying not to let Grace's sudden agitation make me anxious.

" The ship just shut down. Everything stopped working. " Oh. Oh no. I skittered around in my tunnel, listening to the ship. Everything seemed quieter because none of Grace's equipment was making the noises it usually did. Normally it was quite loud, because of the inefficient energy system that Humans use, but now it was silent.

"You equipment quiet now." I informed it, "My equipment still working."

" Your equipment gets electricity from your generator. Mine's powered by my ship. All lights are off. There's nothing working at all. " Ah, the lights were off. That must be what had alarmed it so much.

"This is bad?"

" Yes, it's bad! Among other problems? I can't see! " Grace was not doing a very good job of staying calm. Not that I blamed it; If the ship wasn't working then there were a lot of very important systems that weren't running anymore. Several of which were responsible for keeping Grace alive.

"Why ship turn off?"

" I don't know. Do you have a light? Something you can shine through the xenonite into my side? "

"No, why would I have light?" Grace didn't comment on that. Instead it began trying to move away from its lab equipment. It was immediately obvious that without light it had absolutely no sense of where anything was around it. It reached out its hands, trying to feel its way around the room, but that did very little to help it.

" Where's the ladder to the control room? " It asked, waving its arm somewhere to the right of the ladder. It was barely half a metre in front of it.

"Left." I told it. "More left. Continue... yes... reach forward..." Grace fumbled as I directed it, then finally managed to put a hand on one rung of the ladder.

" Thanks ." It said.

"Amaze! Humans helpless without light."

" Yes. Come to the control room. "

"Yes." I skittered through the tunnel, climbing up to my control room bulb. Grace was slower, even more so than usual, taking great care while navigating the ladder. It used that ladder several times every cycle, but evidently it couldn't rely on its own memory of where the rungs were. As it emerged into the room it turned its head this way and that, still searching.

"Control room also have no light?" I asked it.

" Nothing- wait... I see something... " It's attention was now fixed in the direction of its control panels. It entered the room fully, fumbling over to its chair and sitting itself down. It brought its head as close as it could to the control panel. Whatever it had noticed must have been light based, because it sounded exactly the same as usual to me.

Grace reached out and pushed a button. There was a whir as something turned on, so something was still working at least. Grace was watching its screens now, the way it did when it was looking for information.

" Okay, " it muttered to itself, " how do I use the batteries...? " I would have liked for Grace to be talking to me instead of to itself, since I still had absolutely no idea what was happening.

"Progress?"

" Hang on ." I wriggled in frustration, but stayed quiet while Grace searched its control panel. Grace wasn't very good at talking about what it was doing while focusing on its task. Hopefully this was something it could resolve quickly, and then it could explain what had happened. It found a small hard covering with a switch underneath. It lifted the cover, and flipped the switch, and there was more noise around the ship as other things turned on. It was still too quiet, but it was progress.

" Partial success, " Grace reported. Some of the tension left it, but it was still clearly agitated. " My emergency battery engaged. But my generators are still offline. "

"Why no work?"

" I don't know​. "

"You air is okay? No power, no life support. Humans turn oxygen into carbon dioxide. You will use all oxygen and become harmed?" I was aware of the irony that I was now concerned about a lack of oxygen. But I still remembered Grace trapped under its chair, struggling to breathe. If the ship ran out of oxygen I wouldn't be able to fix it by setting myself on fire to come assist it.

" It's okay, " Grace assured me, " The ship is pretty big. It'll take a long time for the air to be a problem. It's more important that I find the cause of this failure. "

"Machines break. Show me. I fix." I suggested.

" Maybe. But first I need to figure out why two generators would both die at the same time. "

"Good question. More important: can you control ship without power?" I asked it, although I was already pretty sure what the answer was.

" No. I need power to do anything. "

"Then most important: How long until orbit decays?"

Grace stiffened. It clearly hadn't considered that. " I... don't know. "

"Work fast." I suggested.

" Yeah ." Grace pointed at one of its screens. " First I have to wait for my computer to wake up. "

"Hurry."

" Okay, I'll wait faster. "

"Sarcasm." I grumbled. My fidgeting was now pure anxiety. We weren't actually in immediate danger. It wasn't as though we were going to crash right away now that the ship systems were down. But we also wouldn't have any kind of warning before that happened. At least we weren't getting tossed around the room during this particular catastrophe.

Grace didn't respond. It was watching its screens intently.

"What is happen?"

" The screen came up with information ."

"What is wrong?"

" Let me read! " I fidgeted some more. Grace was a slow reader, and I hated not being able to do anything. Finally it continued: " The ship's keeping me alive, but not doing anything else right now. " Well, at least it wasn't going to run out of oxygen or freeze to death before we burnt up in the atmosphere.

"Give me generator, I fix." I insisted.

" First I need to find it. "

"You not know where ship parts are?!" I was incredulous. That was very vital information not to have, even for someone who wasn't the ship engineer.

" The computer has all that information! I can't remember all that! "

"Human brains useless!"

" Oh, shut up! "

Grace got up from the seat, and climbed down the ladder to the lab. I hurried down my tunnels after it. I was trying to calm myself down as we climbed. Sniping at each other was not very productive, and we really needed to be productive right now. Grace grabbed a bag of equipment from the lab, and continued down towards the dormitories.

"Where you go?"

" The storage area. It's the only place I haven't completely searched. And it's the very bottom of the crew compartment. If the generator is accessible to the crew, that's where it'll be. " That made sense. The generators had to be somewhere accessible to the crew, so that they could service them if something went wrong. I reminded myself that Human brains aren't actually that useless, Grace was very good at using logic even if it couldn't remember a lot of things.

I didn't have any tunnels or anything in the storage space. It was too small and full of things, and having access to it hadn't really been worth the xenonite it would have used up. So I had to wait in the dormitory while Grace squeezed itself inside. After a while of crawling around it stopped and lay down for a while, not doing anything. It was breathing harder than usual, and I didn't think it was just from exertion. All that climbing around was probably hurting its arm. I fidgeted some more, wishing there was something I could do to help.

" Rocky, " It said eventually, " are there any doors in here? " It must be having trouble finding them with its light sense. I tapped against the wall of my enclosure, listening carefully to the feedback.

"Six small doors." I informed it.

" Six?! Ugh. " Grace didn't seem to be enjoying its time in the storage compartment. " Tell me where the first one is. "

I directed it to the closest door. It had to use a tool from its bag to open it. There was some kind of pipe behind it, which was clearly not what Graces wanted because it closed it again soon after.

" Next door ." It said. We repeated this a few times. It would have been a lot faster if I'd known what a Human generator sounded like, but I wasn't really familiar with the technology on the Hail Mary. And apparently Grace wasn't either, so it couldn't tell me what I should be searching for. The first three doors held nothing of interest, but behind the fourth it found its target.

" Found it " Grace called.

"Good. Take out and give to me."

" I want to look at it first. "

"You bad at this." I reminded it. "I fix."

" The generator might not survive in your environment! "

"Mmmm" I grumbled. But Grace wasn't wrong. When building the ship the Humans seemed to have given very little consideration as to whether the components would survive in temperatures above 200°C. I didn't like this. I wanted to be able to fix the problem, and get the ship working again. That's what I was for .

" If I can't fix it, you can talk me through it ." Grace said.

"Mmm." I sat and listened as Grace inspected the engine. It unscrewed a hose from one side of it, and then another from the other side.

" Ugh, God! " It said, recoiling from the device as the second hose came off.

"What is problem?"

" The fuel smells bad ." Grace said.

 "Is natural smell or chemical smell?" I asked. Grace inhaled in near the hose again.

" Smells like rotted food. Astrophage doesn't usually smell bad. It doesn't normally have an odour at all. "

"Astrophage is alive. Maybe Astrophage can rot."

" Astrophage can't rot. How could it rot- OH NO! OH GOD NO! " Grace voice got much louder suddenly. It sounded afraid, like it had when the ship was accelerating out of control. It made every muscle in my body tense with anxiety. Grace wriggled out of its compartment, holding out one hand while it scrambled up the ladder. That doesn't seem safe, but I was more concerned about whatever it was clearly panicking about.

" What is wrong​? " I tried to ask, but Grace was too upset to answer me.

" No, no, no, no... " Grace's voice was steadily rising in pitch. Its heart was beating so hard I could hear it through it's fleshy exterior. I really, really wished it would talk to me and explain what was going on, because this was terrifying .

It arrived in the lab, and rubbed its hand on one of the slides of the microscope. It grabbed a tool and held it underneath it, pressing its eyes to the tube. " Oh God. " It said again.

"What is problem?" I asked again. My voice has gone high as well with tension. Grace grabbed its own head. It was breathing much harder than it should have been.

" Taumoeba. " It said. " There are Taumoeba in the generator. "

"They damage generator? Give me generator, I fix." I didn't care if my environment damaged it. If it broke, I could fix it. I just needed Grace to let me fix it.

" The generator isn't broken. If there are Taumoeba in the generator, it means there are Taumoeba in the fuel supply. Taumoeba ate all the Astrophage. We have no power because we have no fuel. "

It felt like it took an eternity for me to process what it was saying. Its words just didn't seem to make sense, even though I understood them all. Then understanding settled and brought with it a wave of pure, instinctual terror. My carapace rose so quickly that I accidentally struck it against the roof of the tunnel. That hurt , even after a few cycles of healing, but I barely registered the pain.

"How Taumeoba get into fuel?!" I squeaked.

" There are Taumoeba in my lab. I didn't keep them sealed off. I didn't think to. Some probably got loose. The ship has a bunch of cracks, holes, and leaks ever since we almost died at Adrian. Some small hole in a fuel line somewhere must have let the Taumoeba in. It only takes one. "

"Bad!" I quavered. "Bad bad bad!" Grace was breathing really fast now.

" We're dead in space. " It said, " We're stuck here forever. "

"Not forever" I corrected.

" No? "

"No. Orbit decay soon." I reminded it. "Then we die."

Chapter Text

Grace spent many more hours after that inspecting every fuel line that it had access to. The Taumoeba was everywhere . Which made sense, because if the Taumoeba had access to the fuel then it had access to everywhere the fuel might go. I had been able to do exactly nothing during this; There was nothing for me to fix, and I couldn't even help to inspect the fuel lines because I didn't have access to them. For the last 20 hours I had done nothing but watch Grace work and try not to lose my mind.

Grace threw the latest fuel line down onto the desk in frustration. Unsurprisingly it had been no different from the others.

"Hopeless," it said, "The Taumoeba is everywhere."

"I have Astrophage on my side of the partition. Approximately 216 grams remaining." I had brought some aboard to power my own equipment, and for testing purposes. 

"That wouldn't power my spin drive for long. Thirty seconds or so. And it probably wouldn't live long enough. There's Taumoeba everywhere on my side of the partition. Keep your Astrophage safe on your side." 

I thought the problem over for a moment. All of Grace’s Astrophage was dead, and I didn’t have anything close to what would be required to meaningfully move the ship. But while Astrophage was by far the most potent fuel our worlds had ever discovered, it wasn't the only way to provide thrust from an engine. That could be done through simple combustion, and Grace might have enough oxygen for that.

"I make new engine." I suggested. "Taumoeba turn Astrophage into Methane. React with oxygen. Make fire. Make thrust. Get to my ship. Much Astrophage there."

"That's... not a bad idea." Grace mused, "Use Taumoeba fɑrts to propel ourselves through space."

"Not understand word after Taumoeba."

"It's not important. Hang on, let me do some maths." It picked up another thinking machine, and spent a while tapping at it. This one didn't have buttons or a lid, it was basically just a screen. After a while it made an unhappy breathing noise and shook its head.

"It's no good. The ship would get less than 800 metres per second velocity. We can't escape Adrian's gravity with that, let alone cross 150 million kilometres of the Tau Ceti system."

"Bad."

"Yes, bad." Grace agreed. It put down its device, and rubbed its eyes. That was something it did when it was tired. Grace was supposed to sleep eight out of every twenty four hours, but had been awake for going on thirty one hours now. That couldn’t bode well for its mental or physical faculties. 

One step at a time. I didn't have a solution to the fuel problem, and Grace was unlikely to think of one when it had been awake for this long. Grace's generator was shut down, and the ship was running off of emergency power for now. That much I could fix. 216 grams of Astrophage might not be enough to power the spin drives, but it would keep the other systems running for many, many years. I moved up the tunnel so that I was closer to Grace, and tried to talk in a comforting tone.

"Give me generator."

"Why? What good would it do?"

"I clean and sterilise. Remove all Taumoeba. I make tiny fuel tank with my Astrophage. Seal generator airtight. Give back to you. You hook up to ship. Power restored."

Grace rubbed absent-mindedly at its injured arm. "Yeah. It's a good idea. If the generator doesn't melt in your air."

"If melt, I fix." Grace considered this for a moment. I could almost hear its brain grinding, running so far below optimum energy levels.

"Okay. Yeah. That's a good idea. At least we'll have the ship back online." It trudged towards the dormitory. "I'll get the generator."

I tried not to cringe at the sluggish and clumsy way it moved around, and the indelicate way it handled its tools. It really needed to sleep, but I needed the generator before I could start to help with anything. I really, really wanted a way to help.

Grace successfully removed the generator, and placed it in the airlock. I cycled it myself, not wanting to give Grace anything else to do before it got the chance to sleep. Then I brought it to my workbench, and picked up some tools to start working on it.

I spared a hand to point to Grace's nest. "I work on this now. You sleep."

"Make sure you don't get Taumoeba in your Astrophage over there!"

"My Astrophage in sealed xenonite container. Is safe. You sleep now."

"I can't sleep." Grace complained. I pointed more sternly.

"You tell me Humans need to sleep eight hours every sixteen hours. You no sleep for thirty-one hours. You sleep now.”

Grace finally relented, sitting down on its nest. It could be stubborn about the most ridiculous things sometimes, especially when it was tired. "You make a good pint. I should at least try. It's been a hard day. Night. Whatever. A hard day's night." I puzzled over that last sentence as Grace settled into its nest. "Day" can mean two things for Humans. It's the amount of time it takes for the planet to rotate, but it's also the period when the sun is visible to them. Night is the period when it is not visible, because the planet blocks their view of it. But I had no idea what "day's night" was supposed to mean, and my understanding of English grammar really didn't allow for that kind of sentence construction.

"That sentence make no sense." I commented.

"It's an Earth saying. From a song." It closed its eyes, and mumbled quietly: "... and I've been working like a dog."

Apparently Earth songs weren't required to make sense. I turned my focus to the generator. The first thing I needed to do was identify any damaged caused by-

"Whoa!" Grace shouted, sitting up very suddenly, "The beetles!" The sudden noise and movement was so startling that I accidentally dropped the generator . That could have been catastrophic if we were at full gravity. Thankfully 0.5G it just landed gently on the floor. My whole body was tense. What now? What else could possibly go wrong?

"What is problem?"

"Not a problem! A solution!" It stood fully up in the nest. It seemed far more alert than it had moments before. "The beetles! My ship has four smaller ships aboard called beetles! They're made to take information back to Earth!"

I knew about the beetles¹. They had been part of the original mission, when Grace's crew had been intended to stay and die in this system. The beetles had little thinking machines that could navigate them back to Earth without the help of Humans. That would have been very useful to have on my ship, if only to keep Erid informed about what had happened. I couldn't see how they were relevant now though.

"You tell me this before. But they use same fuel, correct? Astrophage all dead now."

Grace shook its head. "They use Astrophage, yeah, but each beetle is self contained and sealed. They don't share air, fuel, or anything else with Hail Mary. And each beetle has 120 kilograms of fuel aboard! We have plenty of Astrophage!"

My carapace lightened as the implications hit me. 480 kilograms of fuel was more than enough to get us back to my ship! 480 kilograms could probably get us across most of the Tau Ceti system. I waved my arms excitedly.

"Enough for us to get to my ship!" I exclaimed, "Good news! Good good good!"

Grace waved its arms too. "Maybe we won't die here after all! I need to do an EVA to get beetles. I'll be right back." It jumped down from its nest, and was part way to the ladder before I'd processed what it was saying.

"No!" I shouted. I abandoned what I was doing and skittered over to the tunnel wall. Thankfully Grace stopped and turned to me, and I tapped the wall for emphasis. "You sleep. Humans no function well after no sleep. EVA dangerous. Sleep first. EVA next." Humans truly could not be trusted to make any choices when they were tired.

"Alright, alright." Grace relented, which was a relief because I didn't actually have a way of stopping it if it was determined. Not without setting myself on fire again, anyway. Our situation was dire, and we weren't sure how much time we had, but the situation would not be by Grace dying during an EVA. I pointed firmly back at its nest.

"Sleep."

"Yes, Mom." Grace grumbled. I knew a Mom was a kind of Human parent, and understood the implication. 

"Sarcasm. You sleep. I watch."

***

Grace slept for over nine hours while I worked on the generator. A few components did melt, but nothing that I couldn't easily replace. A lot of Human technology might be beyond my understanding, but I was well equipped to handle something as simple as a generator.

I cleaned, I sterilised, I mended, and by the time Grace woke up I already had a perfect new generator waiting for it. I had included a tiny little tank of Astrophage, so that the generator could be completely sealed. Hopefully that would prevent any more Taumoeba from invading and eating the fuel again.

After it had completed its morning routine, Grace reinstalled the generator in its little compartment, and the ship systems were fully restored. It was a relief to hear the usual hum of the ship again.

We also discussed how best to use the beetles for what we needed to do next. We couldn't just take the fuel out of them and give it to the engines; Grace's tanks were full of Taumoeba, and any Astrophage we added to them would be consumed immediately. The beetles had their own engines, but they had never been intended to be controlled directly by the crew. Which meant that we were going to need to take them apart and bypass the control system. And by we I meant me, Grace did not have the skill set required for this task. Not that I was complaining, I would rather be doing this work than Grace's right now. So, I thought, would Grace. 

"This doesn't seem like a good idea anymore." Grace's voice said over the speakers in the control room. It wasn't generally skittish about the EVAs, but admittedly this one was considerably more dangerous than usual.

Last time Grace had done this, it had been working under the influence of Adrian's gravity, which had introduced the risk of falling. Now we were in orbit again, but there was still gravity to deal with because the ship was still spinning. With no fuel left we couldn't cancel that rotation, so Grace had to climb to the where the beetles were stored against the centrifugal gravity.

The were no tether points on the tapered end of the ship, Grace would have to tether itself further down. If it slipped... it really couldn't afford to slip.

"Do task." I told it, because it wasn't as though we had any other choice. With the thinking machines running again Grace had been able to calculate our orbit and it was not good. We were making contact with the planet's atmosphere every 90 minutes, accumulating a little bit more drag with each contact. Neither of us were sure how many contacts it would take before it completely destabilised our orbit. Grace would not be safer in the ship, dying as we fell into the atmosphere, than it was out on the hull. I was still concerned for its safety, but I didn't think that would be helpful for it to hear right now. We needed the beetles, and this was the only way to access them.

Grace began its climb, and I fidgeted in my control room bulb. It would be fine, I told myself. Despite my jokes about it Grace was a very skilled person. And a very determined one. I really wished I could hear more of what was happening, but all I could do was track its general position on the hull.

"Status?" I asked after a few minutes.

"Making progress." It reported. I could hear about how far it had climbed, but it was a good sign that it wasn't reporting back any problems, or telling me to wait while it dealt with something.

"Good."

Eventually it reached the cone. I fidgeted some more, unable to do anything but wait. There were vague scraping noises as Grace did something, presumably removing the cover from the beetle's housing.

"Um..." it said after a minute, "Rocky you can make screws right?"

"Yes. Easy. Why?"

"I dropped one." Of course it did.

"Hold screws better."

"How?"

"Use hand."

"My hand is busy with the wrench."

"Use second hand"

"My other hand's on the hull to keep me steady.”

"Use third han- hmmm." Right. It was ridiculous that Humans had four hands, but two of them were useless for anything other than walking. Evolution was usually very economical, so I wasn't sure why it would develop hands of an entirely different shape just for them to be less useful. But I could make more screws. The important thing was that it not drop our only hope of surviving. "Get beetles. I make more screws."

"Okay."

There were more quiet, vague sounds of movement from the cone of the ship. It felt like this part was taking forever. There was no screaming, and no suddenly loss of contact with the hull, so I had to assume that things were going well. I really wanted to prompt Grace for more updates, but I didn't want to distract it during this delicate operation.

There was a clank as something hard struck the hull. That was a little alarming, but Grace didn't react to it.

"Status?" I asked.

"Recovering beetles." Grace reported. I buzzed a little in relief, but I didn't celebrate just yet. I remembered what had happened last time I celebrated prematurely. It was several more minutes before I heard Grace making its way back down to the airlock, and it wasn't until it was inside with the door sealed that I let myself relax. Now it was finally time for me to help.

I got to work as quickly as I could. First I had to make sure that none of the beetle's components melted in my atmosphere. The generator was easy to repair, but the beetles had thinking machines in them. If those parts broke, there was nothing Grace or I could do to fix them, and the beetles would not be able to serve their intended function of returning to Earth.

Hopefully that wouldn't be a real issue, since Grace was going to return to Earth itself when this was over. But space travel was dangerous, and Grace would be travelling without an engineer. If something happened to the Hail Mary on the way back, these beetles would be the only means it had of helping Earth.

I tried not to give too much thought to that scenario, but I was going to be cautious with these beetles anyway. Grace also kept one of the four in reserve, so that it would have a completely unaltered one to send back to Earth. Just in case. It meant we only had three vector points for thrusting, but I could work with that.

Luckily temperature control was very simple with access to Astrophage. I repurposed the Space Catan controls to make an Astrophage-cooled box, which Grace sealed the beetle inside before passing it into my atmosphere. Then I began the process of disassembling and analysing the components of the first beetle, which Grace told me was named " Paul". Yes, the Humans had named the individual beetles. Humans just love naming things².

I spent two hours fully disassembling "Paul", and with Grace's assistance I was able to get the hang of the basic mechanics in play. Obviously I had no hope of understanding how a lot of the electronic components worked, but I didn't need to understand it to physically bypass their circuitry. Once I'd figured out what parts supplied power and what parts controlled thrust I had a very good idea of what I needed to do to create my own control system for it.

The process was incredibly interesting, but I didn't say that to Grace. Given the very dire circumstances I wasn't sure it would appreciate me telling it how much fun I was having. But I had wanted a piece of Earth technology to dissect since I had first seen Grace's space suit, and I was learning so much about Earth electronics. I already had some thoughts about how we might develop similar components using Eridian technology. If we'd had more time I would have happily sat through more of an explanation of how all the parts worked. Unfortunately there we were on a time limit, so I kept to the essentials.

In another hour I had Paul rewired to receive instructions from an audio-driven control, and then I was able to repeat the process much faster for the beetles "Ringo" and "John". And that was the end of the fun part. What came next was going to be considerably more challenging.

***

Grace cycled through the airlock and re-entered the control room, a little out of breath from the exertion. It had had to do another EVA, this time to the back of the ship, to attach the three beetles to the hull, which had involved climbing past the centre point of the centrifuge. It had been awake for about eight hours at this point, but it already seemed tired. Hopefully that would be the last EVA it would have to do under the effect of gravity. Unfortunately I didn't think the next part was going to be much better for it.

"All is well?" I asked.

"Yes. Control for John, Paul, and Ringo are good?" I checked my readout. I had separate control boxes for each of the three beetles, all connected to a readout display. The controls were also linked to microphones that had been attached to the hull, which would allow me to control the beetles. I sent out a test signal, and readout told me it had been received.

"Communication established." I told Grace, "All beetles function and ready." That was good news, but Grace wasn't especially cheery about it. Its body was tense as it strapped itself into the chair. I think it was nervous about this next part.

During the catastrophe Grace had lessened the gravitational force on the ship by unspooling the cables to make it longer. But we couldn't apply thrust to the ship while it was in two halves like this, so we had to bring them back together before I could cancel out the rotation. And since we couldn’t do anything to alter our angular momentum, we would start spinning much faster.

That meant we were going to be dealing with a lot of gravity again. The same amount of gravity that had almost killed Grace last time. There was nothing we could do to avoid it, but at least we were prepared for what would happen this time. I did wish Grace had a different chair though.

"You are ready?" Grace asked, adjusting its screens.

"Yes," I lied.

"The G-forces will be strong. Easy for you, but hard for me. I might fall unconscious."

"Unhealthy for Human?"

"A little unhealthy. If I pass out, don't worry. Just get the ship stable. I'll wake when we stop spinning."

"Understand." Passing out sounded more than a little unhealthy. The Human relationship to sleep was different to Eridians, but I still couldn't imagine it was good for them to be forcibly made unconscious like that. But I was just going to have to trust Grace. I had so far.

"Okay, here goes." Grace poked at some inputs on its screens. What I wouldn't have given for actual, physical controls on this situation. I wouldn't have had any control over them, but it would have been comforting to know they were there. It set the compartments to slowly rotate into the correct position. The centrifuge was still spinning, so this meant that the room was turning upside down from our perspective. Grace was kept in its chair by the straps, and I clung to my handholds to keep from falling. So far so good.

Then came the tricky part. The cables began spooling in, and gravity quickly began to increase. Within seconds Grace was struggling to breathe, its lungs fighting to expand under its own weight.

"You are not healthy!" I squeaked, "Undo this. We make new plan." Grace didn't have enough air in its body to speak, but it shook its head firmly. It sounded like even that took a tremendous amount of effort. The flesh of its faces was distorting, pulling away from its mouth in a way that did not sound right or comfortable.

The only way to get Grace out of this position was for me to fix it. I could hear the ship moving back into the position, and waited until the two halves had re-engaged before applying some gently thrust from the beetles. I had to be careful for this part, because the ship was not actually designed to have thrust acting on it from those angles. That was a problem I would have to solve later, but for now I just had to be gentle.

It was a difficult and frustrating process. Normally when Grace was piloting it had the benefit of its thinking machines to calculate the necessary thrust and angles, but I didn't have that kind of assistance. It took some trial and error but eventually I found the exact thrust I needed.

The rotation slowed steadily, and with it the gravity decreased until finally we were back in Zero G. I floated weightlessly in my bulb, tethered by a single hand still holding on to a handhold.

There was a groan from Grace's chair, and I felt a surge of relief.

"Grace! Are you okay?"

"Uh." Grace rubbed at its eyes. It sounded tired and slow. "Yeah. Status?"

"Rotation rate is zero." I reported. "Beetles hard to control. Correction: Beetles easy to control. Ship powered by beetles difficult to control." Grace laughed gently at that.

"You got it done though. Good job."

"Thank." Grace unstrapped itself from the chair. It was weirdly relieving to hear it move from the chair. It couldn't really do anything to hurt Grace now that we were in Zero G, but apparently I still didn't trust it. Grace tapped at its screens, reading through the information.

"All systems are okay. At least, nothing's damaged further than before."

"Good. What is next action?"

"Now I do maths. A lot of maths. I have to calculate the thrust duration and angle to get us back to your ship using the beetles as engines."

"Good," I said. I was more than ready to be away from this planet.

Chapter Text

It was another six hours before we were finally able to leave. We were both on edge, aware that we were still in a precarious position. Luckily I didn't have to spend the whole time waiting idly. The beetles were currently attached somewhat haphazardly to the ship. I had been careful while zeroing our rotation, but if we tried to turn even their tiny engines on full they would tear themselves right off the ship. 

Grace used its 3D printer to create a model of the Hail Mary's internal structure for me, and while it did its maths I set to work designing and creating new supports for the beetles. It wasn’t too complicated, but it kept me busy. And it was interesting to see the Human design sensibilities that had gone into building the structure. I really hoped I’d have a chance to chat with a Human engineer someday and learn more about their methods and thought process.

Eventually the maths was complete, the supports were built, and Grace did yet another EVA to add them to the places I had indicated. By the time we were in the control room preparing for departure I was a mess of nerves. 

" Ready? " Grace asked from its seat.

"Ready," I confirmed. I had the control boxes for the beetles in front of me again. We had decided it would be most efficient if I kept controlling the beetles while Grace monitored its screens for information about our trajectory. I had watched Grace's attempts at multitasking before and now didn’t seem like a good time for it to try and improve on the skill. Besides, I'd already gotten a good feel for them when I'd been cancelling our rotation.

" Okay... John and Paul to 4.5% "

"John and Paul, 4.5%" I made the necessary adjustments, and there was a very small amount of force on the ship as the beetle's thrusters came on.

" John and Paul to zero. Ringo to 1.1 percent. "

"John and Paul zero. Ringo 1.1"

We went back and forth like this a few times, gently nudging the ship to the angle that we needed, the one that would hopefully lead us back to my ship if Grace’s maths was right. It took a lot of fine tuning but we eventually got the ship positioned at the correct angle.

" Here goes nothing. " Grace said, " All ahead full! "

"John Paul Ringo, 100%" I confirmed. I dialled all three beetles to their maximum speed. Grace was thrown back against its seat by the acceleration, and I gripped two handholds to keep myself in place. My insides buzzed anxiously, remembering how it had felt to be tossed around during the catastrophe. But this force was still well below Erid gravity and I maintained my grip easily. Even Grace adjusted to it quickly. 

" Maintain thrust for three hours, " Grace said, and unstrapped itself from the chair.

"Three hours. I watch engines. You relax," I suggested.

" Thanks, but no time for rest. Want to use gravity while I can. " I managed to keep my reaction mostly internal. Grace had done a lot of intense work over the last 12 hours, including two EVAs, one of which was in gravity, and six hours of complicated mathematics. It should really take a break for a while.

But it would take 11 Earth days to get back to my ship, assuming nothing went wrong, and during the majority of it we would have no gravity. I could understand why Grace wanted to make the most of its scientific equipment while we could actually use it. Still, it would be nice if my friend would take better care of itself.

It was only three hours, I reminded myself. After that it would be forced to slow down for a while.

"I stay here. Tell me how experiments go."

" Will do ." I listened as Grace headed down the ladder towards the lab. The Taumoeba experiment was still set up just as it had been before the ship had shut down. Originally Grace had intended to check on the experiment after an hour, but that had been almost 100 hours ago. There just hadn't been any time to deal with it during the outbreak.

I turned my attention back to the engines. My screen watcher was set up to monitor Grace's screens. Grace had gone through the display with me again before we'd launched, to make sure that I understood which numbers were indicating what. Everything seemed to be at the expected values for the time being.

Idly, I picked one of my hands up and let it drop to the floor, testing the new gravity. The low gravity had been helpful during mine and Grace's early recovery, but it was kind of nice to be at higher levels again. It still wasn’t quite right, but it was closer than I’d been since the journey to Adrian. 

Sometimes I wondered if I would recognise Erid gravity when I felt it again. I had existed weightlessly in this system for many, many years. Now I had had the experience of Earth gravity, half Earth gravity, one and a half Earth gravity, and a brief and terrifying experience with six times Earth gravity. I didn't like to think that the gravity of my own world might be unfamiliar to my muscles.

Well, I had adjusted to a lot of strange things during this ship. I would just have to trust I could handle adjusting back to life on Erid.

My thoughts were interrupted by the sound of Grace in the lab. Its breathing had changed to something shallow and unsteady. That typically was not a good breathing sound. It stepped over from the Venus tank to the Threeworld tank, and I could hear its hands shaking. I didn't like it.

"What you see?" I called down. What I wanted to ask was “Are you okay”, but there was something very volatile in its demeanour just then. 

" Failure. " Grace said, still shaking, " Both experiments. The Taumoeba are dead. "

For a moment I could barely process what it was saying. Dead. They were all dead. We'd failed. We had worked, and fought, and almost died, and almost died again , and we had failed. I don’t consider myself an angry person, in the moment I was utterly overwhelmed by how deeply unfair it all was. So much work. So much effort. So much hope . All wasted. 

I balled one hand into a fist and slammed it into the wall of my bulb so hard that it hurt. I didn't worry about breaking it; I would crack long before the xenonite did.

"Anger" I growled. Grace wasn't faring much better down in the lab.

" All of this work. All of it for nothing. Nothing! " It slammed one of its own fists down onto the lab table, shaking everything on it. " I gave up so much for this! I sacrificed so much! "

The anger in me rose, and rose, until it felt like it was going to burst out of me. And then suddenly it all dissipated. Gone like smoke. In its place I felt hollow, like I hadn't felt since discovering Grace's ship. I slumped heavily to the floor. In its lab Grace was still at the table, bent over to rest its head in its hands.

We stayed like that for a long time, wallowing in despair. For a while I allowed myself the luxury of pure grief, untainted by messy things like hope and determination. Because what was I supposed to hope for now? We had done everything we could, risked everything we had, and we had failed. How were we supposed to keep going after this?

Keep going. For so long I had kept going because I was in freefall with no ground to catch me. Continuing was all my momentum would allow me to do. But meeting Grace had changed that momentum. It had allowed me to change course, to do something different. But it also meant I couldn’t rely on it to carry me forward. If I allowed myself to, I could come to a stop here. I could just let it all be over. 

Or I could keep going. On purpose this time. I flexed the fingers of the hand I had used to punch the wall. It still ached a little from the impact. My carapace still ached from when it had broken open too. My entire being ached from all the loss, and loneliness, and hopelessness of almost 50 years in space. But despite everything, I wasn’t dead just yet. Slowly, carefully, I picked myself up off the floor. 

"We work more," I said, loud enough for Grace to hear, "We no give up. We work hard. We are brave."

Grace was quiet for a moment, then breathed out heavily. " Yeah. I guess so. " But it didn't spur into action. Instead it sat down heavily on its seat in the lab with its head facing down at the table. The anger seemed have left it too, and now it just seemed vacant.

I knew what it was like to come up against a wall like this. Before Grace arrived, all I'd had were walls. No matter what I did I hadn't been able to move forwards, because I lacked the equipment, the skills, and even the basic knowledge to do what needed to be done. I knew how much it hurt.

But things were different now. We had each other. I checked the screen watcher's readouts; We had been stable this whole time, all the numbers holding in the expected ranges. It would be fine if I left it for a moment, so I left my bulb and climbed down to the lab. Grace didn't register my presence at all, but I didn't interrupt it. I just took a seat and waited for it to be ready. Finally its head lifted to face me.  

"You are very sad." I said.

" Yeah. "

"I am sad also. But we not be sad for long. You are scientist. I am engineer. Together we solve."

Grace threw its arms into the air angrily. " How?! "

I stood, and walked down the tunnel until I was as close to Grace as I could be. "Taumoeba eat all your fuel. Therefore Taumoeba survive and breed in fuel-tank environment."

" So? "

"Most life no can live outside its air. I die if not in Erid air. You die if not in Earth air. But Taumoeba survive when not in Adrian air. Taumoeba stronger than Erid life- stronger than Earth life." Grace turned to face me. It had to bend its head all the way back to do it from where it was sitting.

" True. And Astrophage are also pretty tough. They live in vacuum and on the surface of stars. "

I clicked two fingers in agreement. "Yes yes. Astrophage and Taumoeba from same biosphere. Probably evolve from common ancestor. Adrian life is very strong." Mycelium would have admonished me for being so reductive. No kind of life was "stronger" than other life. All life was evolved for its particular niche, with all the specificity that entailed. But that didn't matter. What mattered was the way Grace's face had changed.

It straightened up. " Yeah. Okay. "

"You have idea already. Not question. I know you. You have idea already. Tell idea."

" Well.. Venus, Threeworld, and Adrian all have a bunch of carbon dioxide. The Astrophage breeding zone in all three is where the pressure is 0.02 atmospheres. So maybe I'll start with a chamber full of pure carbon dioxide at 0.02 atmospheres and see if Taumoeba survives that. Then add in more gases one at a time to see what the problem is. "

"Understand."

Grace got to its feet. Despite it all I felt a twinge of excitement to hear it getting back into action. " I need you to make me a test chamber. Clear xenonite with valves so I can let air in and out. Also I need to be able to set temperature to -100 o C, -50 o C, or -82 o C. "

"Yes yes. I make now. We are team. We fix this. No be sad."

I started down my tunnel towards the dormitory to work on it. Grace checked its miniature on its arm. " The main thrust ends in thirty-four minutes ." It said, " After that's done, let's use the beetles to put ourselves in centrifuge mode. " That made me pause. We had both agreed that it was best not to try and deal with rotation while we were in transit.

"Dangerous."

" Yeah, I know. But we need gravity for the lab and I don't want to wait eleven days. I want to make good use of time. "

"Beetles arranged for thrust, not rotation."

" It's worth the risk. " Grace insisted. Okay, so it was in one of its stubborn moods again. Sometimes it seemed like Grace would arbitrarily decide that something was worth arguing about, and it was so difficult to get it to listen to reason. I came back fully into the lab to try anyway.

"Ship will rotate off-axis. No can unspool centrifuge cables. Would tangle." I explained patiently. Grace should already know all of that, because it was the one that had explained it to me when we had first been planning how to cancel the ship's rotation.

" We'll create the needed rotation first, then shut off the beetles, then unspool the cables. " That made me so aghast I drew back a little, as if I could hide from the idea.

 "If ship not unspooled, force is too much for Human."

Grace considered this, and for a moment I dared to hope that it was going to listen to sense. I probably should have known better. Presenting a scientist with a reason they can't do something triggers their innate puzzle solving instincts.

" Okay... How about this: I'll lay down in the storage room under the dormitory. That's the closest to the centre of the ship I can get. The force will be smallest there. I'll be okay. " Oh, so it wasn't even planning to be properly secured to a seat for this. This plan was getting better by the moment.

"How you operate a centrifuge controls from the storage room?"

" I'll.... umm... I'll bring the lab's control screen down there with me. I'll run data and power extension cables from the lab to the storage room. Yeah. That should work. "

"What if you unconscious and no can operate controls?"

" Then you cancel the rotation and I'll wake up. "

"No like. Alternate plan: Wait eleven days. Get to my ship. Clean out you ship fuel tanks. Sterilise- make sure no Taumoeba. Refill with fuel from my ship. Then can use all functions of you ship again."

" I don't want to wait eleven days. I want to work now. "

"Why?" I asked in frustration, "Why no wait?" Grace paused for a moment, considering how to answer.

" Human thing. " It said finally, like that settled the matter. I really wished there we weren't separated by our atmospheres so I could shake some sense into it. I also really wanted to keep arguing with it, but I could tell that it wasn't going to get us anywhere. Grace had found its determination again, and it was using it to insist on the least safe, least sensible path forwards. But at least it was choosing to move forwards.

"Understand." I said, wearily. "Not actually understand but... understand."

***

The Space Catan control system worked perfectly. I'd recovered it from the cool box, where I had used it to work on the beetles, and after a little bit of fine tuning I got it set up on the wall in the dormitory. It took Grace a little bit of practice to get used to, but then it was able to interact with the pieces exactly the way an Eridian would.

It would have been a great way to pass the time if Grace hadn't been so busy. The rotation had gone about as well as we could have hoped; Grace claimed the gravity hadn't been a problem, although it had seemed shaky for a little while afterwards. But Grace was entitled to make its own terrible choices about its health. Over the last two cycles it had done nothing but obsess over the Taumoeba. Not that I didn't understand the fixation. The survival of my world was also at stake, after all. I just wished it would slow down a little.

For two cycles it mostly shut itself in its lab, only taking breaks to eat and sleep. Those would have been less regular too, but I was monitoring it to make sure it didn't work itself into illness. I can be stubborn too when I need to be.

It was a very uneventful trip for me. Technically there was much more on the ship that needed repair now, but a lot of it was Human science equipment that I did not know how to fix. Strangely though I still felt a lot less anxious than I had on the trip to Adrian. Having actual and present dangers to worry about was somehow a lot less taxing than worrying about things in general. At least now I knew what things I needed to monitor.

And Grace did seem to be making progress. It hadn't told me much about its findings yet, but most of its mutterings were either curious or confused, rather than frustrated or despairing.

Early in the third cycle I heard Grace calling to me from the lab. I was in the control room, checking on our progress. Grace had made sure to keep the screens on the same setting most of the time, so that I would know where all the information was.

" Hey Rocky! " It said, " Watch me pull a Taumoeba out of hæt ! " I had no idea what a "hæt" was, but it sounded like Grace finally had something to share. I left my bulb and climbed to the lab tunnel.

"I assume that is Earth idiom."

" Yeah, Earth has entertainment called ‘ ˈtɛləˌvɪʒən ’, and- "

"Do not explain please. You have findings?" I was sure whatever ˈtɛləˌvɪʒən was was very interesting, but I really wanted to hear about whatever Grace had found.

 " I have some results. "

"Good good." I settled myself down nearby, so I wouldn’t fidget while it was talking. I was a little anxious about whatever it might have found. Grace didn't seem upset about it though, which was promising. "Tell findings!"

Grace gestured to the equipment I had made " This functions perfectly, by the way. "

"Thank. Tell about findings."

" My first experiment was Adrian's environment. I added Taumoeba and a slide covered in Astrophage. The Taumoeba survived and ate it all. No surprise there. "

"No surprise." I agreed. "Is their native environment. But proves equipment works."

" Exactly. I did more tests to learn Taumoeba's limits. In Adrian air, they can live from -180 o C to 107 o C. Outside that range they die. "

"Impressive range." I commented. That was a range of almost 300 o C. The upper range made sense. It could survive temperatures a little warmer than Astrophage, which was at the very least a major food source for it, if not its main food source. -180 o C was interesting though. That was more than 100 o C lower than the environment it lived in. Did the temperatures in the upper atmosphere drop much lower sometimes?

But that was a mystery for another time. The salient information was that it could easily survive in the temperatures of Venus and Threeworld.

" Yes, " Grace agreed. "Also, they can survive in near vacuum. "

"Like your fuel tanks."

" Yeah, but not TOTAL vacuum. They need carbon dioxide. At least a little bit of it. I made an Adrian environment but put argon in instead of carbon dioxide. The Taumoeba didn't eat anything. They stayed dormant. Eventually they starved to death. "

"Expected. Astrophage need carbon dioxide. Taumoeba from same ecology. Taumoeba also need carbon dioxide. How they get carbon dioxide in fuel tanks?"

" I had the same question! So I did a spectograph of my fuel-bay sludge. There's a bunch of CO 2 gas dissolved into the liquid. "

That was surprising. But I only had to think about it for a moment before an answer presented itself. "Astrophage probably have carbon dioxide inside. Or decomposition creates carbon dioxide. Some percentage died in fuel tanks over time. Not all cells are perfect. Defects. Mutations. Some die. Those dead Astrophage put carbon dioxide in tanks."

" Agreed ."

"Good findings." I said. It was a lot of good information about the tolerances of Taumoeba. I stood up, to head back to the control room, but Grace stopped me.

" Wait. I have more. Much more. " I stopped.

"More? Good."

Grace leaned against its lab table, patting the testing tank. " I made Venus in this tank. But not quite Venus. Venus's air is 96.5 percent carbon dioxide and 3.5 percent nitrogen. I started with just the carbon dioxide. The Taumoeba were fine. Then I added nitrogen. And the Taumoeba all died. "

I lifted my carapace in surprise. "All die? Sudden?"

" Yes. In seconds. All dead. "

"Nitrogen... unexpected."

" Yeah, very unexpected! " Grace agreed, " I repeated experiment with Threeworld's air. Carbon dioxide only: the Taumoeba were fine. I added in the sulfur dioxide: The Taumoeba were fine. I added the nitrogen: Boom! All the Taumoeba died. "

I tapped a claw against the wall, taking all that in. "Very very unexpected. Nitrogen harmless to Erid life. Nitrogen required by some Erid life."

" Same with Earth. Earth's air is 78% nitrogen. "

"Confusing." I said. The evidence strongly suggested that life on Earth, Erid, and Adrian were all distantly related. Our DNA simply had too much in common to be a coincidence, given our proximity in space and the evident existence of life able to travel between stars.

So if nitrogen was harmless to all life on our worlds, and some life forms from both our worlds even needed nitrogen, why would it be so deadly to Taumoeba? Presumably whatever ancestor had seeded our worlds had been fine with it, or life would never have begun on Earth and Erid. And even Astrophage must have no problem with it, because it was thriving on Venus and Threeworld.

It was an interesting question. But it also didn't really matter, in the short term. In the short term the only thing that mattered was that we really had failed. It hit me all at once; Threeworld and Venus both had nitrogen in their atmospheres. Nitrogen killed Taumoeba. We couldn't remove the nitrogen from the equation, which meant Taumoeba would be useless on those planets. My carapace sank.

"Situation bad. Threeworld air is 8% nitrogen." Grace sat itself on a seat, knotting its arms together in front of it.

" Venus's air is 3.5 percent nitrogen. Same problem. " I sank even further.

"Hopeless. Cannot change Threeworld air. Cannot change Venus air. Cannot change Taumoeba. Hopeless."

" Well, " Grace said, before I could slump too far into depression, " We can't change Threeworld or Venus's air. But maybe we can change Taumoeba. " Well that was an interesting proposal. Did Earth have the technology to do something like that? And more importantly, was it available on the Hail Mary?

"How?" I asked.

Grace picked up the flat thinking machine from the table, and tapped on the screen to find some information. " Do Eridians have dɪˈzizəz ? Sicknesses inside your bodies? "

It was asking about diseases, but I had no idea where it was going with it. "Some. Very, very bad."

" How does your body kill diseases? "

"Eridian body closed. Only opening happen when eat or lay egg. After opening seals, area inside made very hot with blood for long time. Kill any disease. Disease can only get into body through wound. Then is very bad. Body shut down infected area. Heat with hot blood to kill disease. If disease fast, Eridian die." I was lucky that the Hail Mary was a very sterile environment, and I hadn't gotten any infections after the damaging my carapace during the catastrophe. If that had happened I definitely would have died.

" Humans are very different. We get diseases all the time. " Grace said. That made a lot of sense; Grace had five open orifices just on its head, and the eyes also presented a potential entry point. And its exterior was so soft it probably got damaged all the time. It really was a wonder that they had survived long enough to become an intelligent species.

" We have very powerful immune systems, " Grace continued, " Also we find cures for diseases in nature. The word is ˌæntibiˈɑtɪks ¹. "

I tilted my carapace curiously. "No understand. Cures for diseases in nature? How?"

" Other life on Earth evolved defences against the same diseases. They emit chemicals that kill the disease without harming other cells. Humans eat those chemicals and they kill disease but not our human cells. "

Huh. I had no idea that was possible. Was that a technique we could employ on Erid, or did it only work with Human biology? "Amaze. Erid no have this."

" It's not a perfect system, though. Antibiotics work very well at first, but then over the years they become less and less effective. Eventually they barely work at all. "

"Why?"

" Diseases change. Antibiotics kill almost all the disease in the body, but some survive. By using antibiotics, Humans are accidentally teaching diseases how to survive those antibiotics. "

"Ah!" I said, understanding, "Disease evolves defence against chemical that kills it." It was the basis for all evolution, essentially. An environmental pressure was introduced, and the organisms that survived would breed and produce more organisms that were likely to survive that pressure.

" Yes. Now think of Taumoeba as the disease. Think of nitrogen as the antibiotic . " I thought about it for a moment, and then my carapace raised in excitement.

"Understand! Make environment barely deadly. Breed Taumoeba that survive. Make more deadly. Breed survivors. Repeat, repeat, repeat!" Grace was suggesting a kind of targeted evolution. Taumoeba had a very short doubling period, which meant we could breed many generations of it over a short period of time. All we had to do was create the correct environmental conditions that would ensure that only the Taumoeba with the traits we needed were bred. It was simple, it was elegant, it was a perfect solution!

" Yes, " Grace said, " We don't need to understand why or how nitrogen kills Taumoeba. We just need to breed nitrogen-resistant Taumoeba. "

"Yes!"

" Good. " Grace slapped a hand down on top of the testing tank. " Make me ten of these, but smaller. Also provide a way for me to get Taumoeba samples without interrupting the experiment. Make a very accurate gas injection system- I need exact control over the nitrogen quantity in the tank. "

"Yes! I make! I make now!" I scurried away along the tunnel to the dormitory. There was so much energy in my body I felt like I was going to shake apart. This was it. If we could breed nitrogen-resistant Taumoeba, then we would be done. We could go home.

The longing hit me again, so strongly that it hurt. I had to sit on the floor of the dormitory to try and calm down. Home. Since meeting Grace I had been trying to hold onto hope, but it had always been tempered by the fear that I would hurt myself with it again. I had lost many- figurative- fingers to that particular tool.

But now I was close enough to our goal to hear it. Now all of the feelings that I had been unconsciously holding back came flooding over me. I wanted to go home. I wanted to sleep in a normal room without worrying that a system malfunction would kill me before I woke. I wanted to run and run and run and never run out of room to just keep going. I wanted to hold someone's hand again. Adrian's hand, if it was still available to me.

I allowed myself a few more minutes to let it all wash over me. Then I picked myself up off the floor and got to work. There was one more hurdle left to overcome, and I wasn't going to do it by sitting around.

Chapter Text

Grace examined the readings from its spectograph, muttering to itself. I had gotten quite good at identifying when Grace was talking to itself, and had largely learned to tune it out. Finally it shook its head at the results. 

"No good. Complete failure." 

"Sad." I said flatly. Grace paid no attention to my tone, it just leant forward to rest its head on its hand. 

"Maybe I can filter out the toxins." 

"Maybe you can concentrate on Taumoeba." Grace turned to look at me. I was getting better at telling its mood from its face shapes too, and I would describe that particular shape as "unimpressed". I felt much the same. 

"They're getting along fine." Grace said dismissively. "Nothing to do but wait. We've had good results. They're already up to 0.01% nitrogen and surviving. The next generation might be able to go as high as 0.015." 

Grace had begun the breeding process the moment the tanks were ready, and it was agonisingly slow. I mean, in evolutionary terms it was incredibly fast thanks to the speedy doubling time of Taumoeba. But in terms of sitting around waiting it was very slow. We were seeing results; 0.01% may not sound like much, but it was a vast improvement from where we started. And it was a very, very long way from where we needed to get to. 

I could see Grace’s point, there wasn't actually anything we could do that would make this process go faster. But there had to be a better use of the waiting period than this. 

"This is waste of time. Also waste of my food." 

"I need to know if I can eat your food." 

"Eat your own food." 

"I've only got a few months of real food left. You have enough aboard your ship to feed a crew of twenty-three Eridians for years. Erid life and Earth life use the same proteins. Maybe I can eat your food." 

I wriggled impatiently. There wasn't any real danger of me running out of food before we got back to my ship. And my ship had enough food to last over 200 years. But I still didn't like seeing it wasted on pointless experiments. I had only given Grace a sample in the first place because I knew it wouldn't stop pestering me if I didn’t.

"Why do you say 'real food'? What is non-real food?" Grace turned back to its spectograph results. 

"Real food is food that tastes good. Food that's fun to eat." The idea of recreational eating was still very bizarre and off-putting to me, but I was aware that it was a thing in Grace’s culture. A very strange thing, but that’s aliens for you.

"You have not-fun food?" 

"Yeah. ˈkoʊməslɜri. The ship fed it to me during the trip here. I have enough to last me almost four years." 

"Eat that." 

"It tastes bad." 

"Food experience not that important."

"Hey," Grace said, turning and pointing at me, "to Humans food experience is very important." 

"Humans strange." Grace ignored the jab, and instead turned its pointing to the screen of its spectrometer. 

"Why does Eridian food have thallium in it?" 

"Healthy." Thallium was part of the metal alloy that Eridian bones are made of. I don’t actually know what it’s specific purpose is, but thallium deficiency is bad for the skeleton. 

"Thallium kills Humans!" 

"Then eat Human food." 

"Ugh." Grace groaned, and walked over to the Taumoeba tanks. It was possible I was being culturally insensitive. Or just regular insensitive.

It was obvious that Grace was worried about its journey back to Earth, it had been fretting over it more and more ever since we left Adrian. Three more years of travel wasn't such a big deal for me. I wasn't looking forward to it but I had already been out here for a very long time, and at least now I would know how long it would last. But Grace hadn't actually experienced much of its time in space. It had slept all the way here, and now it was facing the prospect of being alone on its ship for four years.  Maybe it hoped that more "fun" food would make that easier. 

Unfortunately that was not something I could help it with. I couldn't make my food less deadly to it. I couldn't engineer more food for it to eat. But the food it had was calorically and nutritionally sufficient, even if it wasn't "fun". It would just have to persevere. 

In the meantime, there was Taumoeba to breed. A LOT of Taumoeba to breed. It had taken us 23 generation to produce Taumoeba that could survive 0.01% nitrogen concentration, and if my world was going to survive we had to get that number to 8%¹. I could only hope that the intervals would increase as we got closer. 

"How long until we reach the Blip-A?" Grace asked, changing the subject. I had mounted one of my clocks in my control room bulb, and I could hear it counting away the seconds. 

"Seventeen hours until reverse-thrust manoeuvre." I told Grace. 

"Okay. Let's spin down the centrifuge now. Just in case we run into trouble and need extra time to fix something." 

"Agree. I go to control room now. You go to storage locker and lie flat. Do not forget control panel with long extension cords." I still didn't like this system, but Grace had admittedly made good use of its eleven days of gravity. At least it didn't fight me on maintaining the safest possible procedure for it. You wouldn't think I'd need to worry about that, but there was no telling with Grace. 

Grace checked around the lab to make sure everything was properly secured down. "Yeah, okay." It said when it was satisfied. "Let's do it." 

------------------------------------ 

I would never have imagined I could be so happy to be back aboard my ship. 

It had taken some effort to link the two ships back together. I couldn't access my hull robot while I wasn't aboard, and manoeuvring the Hail Mary into position using the beetles was challenging. But we finally lined up enough that Grace could reattach the old tunnel. 

Of course that meant that we couldn't use the centrifuge function anymore. But we didn't need gravity to breed the Taumoeba, and it was worth it to be connected again. After so many cycles confined to the smaller quarters of the Hail Mary the space on my ship felt like a luxury. I spent a while when I got back aboard just bouncing around the ship, happy for the room. The ship had been fine in my absence; all the supplies were in tact and there had been no mechanical failures. Everything was about in the condition that I had left it. Of course I had a to do list as long as Grace that I needed to attend to while we bred the Taumoeba, but it was nothing I couldn't handle. 

We needed to clean out Grace's tanks. The fuel tanks weren't made to be accessible, but I could make it something to cut its way into them. And once they were cleaned I'd need to design some kind of pump to transfer fuel from my ship to the Hail Mary. And then I needed to make sure Grace's ship was fully space worthy; It had taken a lot of damage, and Grace wouldn't have an engineer with it to help if something went wrong. 

All of that would be a lot easier if I had a more direct access from my ship to Grace's. Having to cycle through four different airlocks to get from my ship to my enclosure would be a lot of hassle while working. That would mean building a tunnel through the bulkheads of both ships, but I was confident I could do that without compromising either of them. Only if Grace agreed, of course. I wouldn't put more holes in its ship without permission. 

I floated down my ship, towards my dormitory. I hadn't seen the room in almost 14 cycles. It was exactly as I had left it, of course. Still packed with various machines and equipment, although I had taken a lot of supplies onto the Hail Mary. If I had time I really ought to re-oragnise the space before I left the system, it would be nice to have more sleeping space for the trip back. I was planning to keep sleeping in Grace's dormitory until then, where Grace could watch. 

Grace would be leaving soon, I thought. We both would, obviously. Assuming that the Taumoeba breeding was successful, we would go our separate ways in a matter of cycles. 

It was a good thing. I was so excited to go home, and I knew Grace was too. But I was going to miss it terribly. Once I had speculated that space travel would be too dangerous for us to attempt it again, but that was before I had learnt what killed my crew. Now I knew, and I knew how to prevent it happening again. It was possible that Erid would build more ships and visit Earth someday. But that would be many, many years away, and I would still be making this journey alone. Suddenly the large space of my ship felt less inviting. 

I tried to shake off the morose mood. We were on the verge of going home and saving our planets, it was no time to be sad. Leaving the dormitory, I headed back towards the lab airlock. Grace was in its control room on the other side of the tunnel, doing something with the thinking machine. I sealed myself inside my xenonite bubble and cycled through my airlock, then the tunnel airlock, and then knocked on the door and waited for Grace to let me through its airlock. I really needed to make that direct access, I simply could not do this multiple times every cycle. 

"Everything good on your ship​?" Grace asked, as it opened the door for me, and pushed me into the control room. 

"Yes. All systems good. Fuel still good. Have plenty to refuel you ship." 

"Good good good." Grace said, closing the doors behind us. 

"We need to sterilise you ship first. I can make tool to help access fuel tanks." 

"That's great, thanks Rocky." Grace said. It had turned back to its thinking machine screens, distracted by whatever it had been doing before.

"You look for information on machine?" I asked it. 

"Huh? Oh, yeah I'm just checking the Hail Mary systems." 

"You did that already." 

"Yeah, I thought I might as well give it another look over now that we're linked up again." 

Grace had been doing that a lot recently. Checking the system, checking its supplies, checking information about space travel, testing my food. Not that I didn't understand its concern; The ship had taken a lot of damage when we had almost died in orbit around Adrian. But it felt less like Grace exhibiting a reasonable level of concern over a legitimate problem and more like me obsessively asking it about oxygen levels. I wasn't going to say that to it. Instead I tried to shift it to a more productive conversation. 

"How long until next Taumoeba test?" I asked. Grace checked its clock. 

"About an hour." 

"Exciting!" 

"Yeah. We've still got a long way to go, but very exciting." It didn't sound very excited. I pushed on. 

"How long you think until we have Taumoeba-35?" Grace had taken to naming the Taumoeba strains after the percentage of nitrogen it could resist. Taumoeba-35 would be nitrogen that could resist 3.5% nitrogen.  I was following the convention because it made conversation about it easier. 

Grace breathed out heavily as it thought. "Hard to say. Maybe another few weeks? The progression isn't exactly speedy." 

"Still. Exciting!" 

"Yeah, exciting." It was obvious that most of its attention was on its screen, intent on checking its systems. Talking about the work was clearly not going to break it out of this mood. I tapped a finger thoughtfully against my bubble. 

"What is Earth like?" I asked. That question surprised Grace enough for it to turn to face me. 

"What?" 

"Earth. Want to know what Earth is like." 

"Uuuuh... depends were you are, I guess. Earth is different all over. Different temperatures, different biomes, different people, different cultures. Everywhere is different." I clicked two fingers, affirmatively. 

"What is you part of Earth like?" Grace thought about that. 

"My part is... noisy. Lots of people. Lots of buildings. Not so many plants and other animals." 

"They not live there?" 

"Not as many anymore. When Humans build cities it tends to drive out a lot of the other life. But there are still plants and birds and bugs and things. Just less than there used to be." Grace had told me a little about plants and bugs, although I wasn't sure what a "bird" was. Presumably it was some kind of native Earth life. 

"You have favourite life?" I asked Grace. 

"Favourite life?" 

"Favourite life. Life form you like looking at, or being near. I like Evil Fish². They live in ocean. Build nest from rocks. Make interesting geometric patterns." 

"Earth has some animals like that." Grace smiled, then turned its head away while it thought about the question. "I like trees. " 

"What is that?" 

"They're a kind of plant. Well, they're actually lots of different kinds of plants. Some of them aren't that closely related. But they have a similar structure, mostly. They're very tall, to be close to the sunlight. The top part is covered in something called 'leaves', which they use to capture energy from the sun." 

"Earth life is amaze." I say. "Eat sunlight. Like Astrophage."

Grace laughed at that. "They don't eat that much. But they're cool to look at, and lots of other things live in and around them. And they cast big shadows, so you can sit under them when the sun is very bright and it will be cooler." 

"Sounds like interesting life. You will sit under one when you go home?"

"Maybe. Thought it might be a while before its warm enough to be sitting under trees again." Its face did some of that complicated folding. "You know I used to take the kids outside to learn when it was a nice day. I wonder if the trees at the school are still there." 

That took me by surprise. "You have offspring?" It was the first I had heard of it. 

"What? Oh! No, I was a teacher. I uh, I taught children things about science." 

"You teach children? I not know this." 

"I do. Did. I stopped doing science for a while to teach. Then I went back to science when Astrophage started eating the sun."

That was... surprising information. Not so much that Grace taught science to people; It had been very good at teaching me about new concepts and I could imagine it applying that skill to others. But I was surprised that it had stopped doing science for it. Grace was very good at science, and it seemed to enjoy it. Was it not allowed to do both? On Erid mentors were normally still very active in their fields.

Of course on Erid someone as young as Grace would never be considered eligible to teach anything. My mentor had been over 400 years old when it began mentoring younger engineers. And caring for groups of children was generally considered work for people in their 500s at least. But I had no idea how education was handled on Earth. Maybe Humans just didn't like their educators to do things other than educating. 

"Understand. I choose Eridian word for life form." I already had an idea for what to call it. It was a really stupid idea. Grace would love it. "It called... tree." Grace's face scrunched up thoughtfully. 

"That sounds a lot like the word you use for my name." 

"Yes. Is kind of word joke. Word for "grace" is like word for "big". Put together. Name for life form is 'big Grace'." Grace made an ugly breathing out noise, which devolved into laughter. 

"pʌn" It said, still laughing gently, "A joke using words that sound similar is a pʌn." 

"Understand. Eridian word is 'pun'. Would like to hear tree someday, it sounds like good life." 

Grace perked up. "I could show you some pictures on the computer. I have information about basically everything on there, you can look at it with your camera." 

"Good good. First let me into enclosure. Not want to stay in bubble" I said, gesturing around me. 

"Oh, right. Hang on." 

Grace moved away from its computer and began pushing me towards the dormitory. It seemed in slightly better spirits than when I had first come in. That was good. I didn't know how interesting trees really were, but that wasn't the point. The point was Grace's smile while it pushed me along, telling me anything it knew about trees from memory. The journey ahead of us would be lonely for both of us, I couldn't do anything to change that. But we still had some time left together, and we could still make the most of that. 

----------------------------------

Generally I tried not to be disruptive while Grace prepared itself for sleep, but it was difficult to contain the urge to bounce around my enclosure. I was compromising by holding onto my workbench and gently pushing and pulling myself back and forth. 

"Happy! Happy happy happy!" Grace was also trying to keep its composure, but it couldn't help the wide smile on its face as it secured itself to its nest. 

"Yes! But we're not done yet!" That was Grace trying to be noble about it. But I knew it was a lot more excited than it was letting on. How could it not be? Sitting on the floor was a small tank, and in that tank was what had to be the most important achievement in the history of Grace's world. 

"Taumoeba-35! Took many many generations, but finally success!" Many many generations. It had been a little over five cycles since we had connected the ships, and we had bred over 144 generations of Taumoeba in that time. As I said, science is powerful, not fast. And so much of the process was just waiting around for the Taumoeba to breed, sometimes I felt like I would shake apart from the anticipation. 

But it was worth it. It was so, so worth it. We had bred Taumoeba capable of breeding on Venus! Theoretically capable, anyway. Grace still had to do a lot of tests on it to make sure there were no other issues. But still, it was hard to imagine a more monumental moment for Grace and its people. It should really be celebrating more. 

"You. Be happy now." 

"I am, I am. But we need to get to 8% so that it can survive on Planet Three. Until then we're not done." I wondered if it was an Earth culture thing to reserve your excitement until the very end of the project, or if it was just Grace. Or maybe it thought it would be inconsiderate to celebrate when the future of my own world was not yet guaranteed. 

"Yes yes yes. But this is moment. Important moment." 

"Yeah." Grace said, its smile widening. That would have to do for now, Grace needed to begin its sleep cycle soon anyway. I turned most of my attention back to the new device I was working on. There had been a lot to keep my busy while waiting for Taumoeba to breed. Grace had allowed me to build my new tunnel between the ships, and now I could travel freely back and forth to work and gather materials.

Which was good because between working on Grace's ship and making preparations for my own, there was a lot of work to do. I was prioritising the Hail Mary, since I could always make more modifications to my own during the journey. But this particular project had to be finished before we parted ways. This device was going to revolutionise Eridian technology. 

Okay, that's very dramatic. But it was actually going to do that, if I got it working correctly. 

"Now you make exact Venus atmosphere in one tank and do detailed test on Taumoeba-35?" I asked as I continued working. 

"No. We'll keep going until we get to Taumoeba 80. It should work on Venus and Planet Three. I'll test everything then." 

"Understand." 

Grace turned itself so that it was facing me. "What are you working on?" 

"This is Earth electricity unit." I explained 

"You're making a power converter?" 

"Yes. Convert from Eridian prime-sequence electrical amplitude to inefficient Earth direct-current system." 

"Prime sequence?" 

"Would take long time to explain." Grace really needed to get to sleep soon, but I made a mental note to talk to it about it later. It was shocking that a species as advanced as Humanity was using something as inefficient as direct-current. Even if Grace didn't fully understand I could at least give it the information to tell other scientists about.

"Okay. What will you use it for?" 

"If all plans work, we make good Taumoeba. I give you fuel. You got to Earth and I go to Erid. We say goodbye."

"Yeah, I guess." It sounded less happy than it had moments before. I understood, I wasn't looking forward to saying goodbye to Grace either. But now wasn't the time to try and deal with all those feelings. 

"You have many portable thinking machines. I ask favour: You give one to me as a gift?" 

"A ˈlæpˌtɑp? You want a ˈlæpˌtɑp? Sure, I have a bunch of them." 

"Good good. And thinking machine have information? Science information from Earth?" Grace smiled again as it understood what I was asking for. Humans had a lot of information about science that was unknown to my people. Even a small amount of it could push forward areas of Eridian science by centuries. And having more information about Earth would make establishing a relationship with Humans much easier once that became relevant. 

"Yes, I can do that. But I don't think a laptop will work in Eridian air. Too hot." 

I pointed at the converter I was building. "This is just one part of thinking machine life-support system. System will give power, keep Earth temperature, Earth air inside. Many redundant backups. Make sure thinking machine not break. If break, no Eridian can fix." 

"Ah, I see. How will you read the output?" 

"Camera inside convert from Earth light readought to Eridian texture readout. Like camera in control room. Before we leave, you explain written language to me." 

"Yeah, sure. Our written language is easy. Kind of easy. There are only 26 letters, but many strange ways to say them. Well, I guess there are actually 52 symbols because capital letters look different even though they're pronounced the same. Oh and then there's punctuation..." 

"Our scholars will solve. You just get me started." I said, cutting off the ramble. Grace's rambles were usually very interesting, but I didn't want it to keep itself awake much longer. I had sort of taken on the responsibility of ensuring Grace got an adequate amount of sleep. Not that I didn't trust Grace, I just didn't trust sleep-deprived Grace. It was amazing how much it struggled with maintaining its own sleep habits; Past a certain number of hours of consciousness it seemed to develop an aversion to sleeping at all. It's a good thing Humans are a social species, because I couldn't imagine they would have survived like that for long if they were solitary. 

"Yes. I'll do that. I want a gift from you too: xenonite. Solid form and liquid pre-xenonite form. Earth scientists will want that." 

"Yes. I give." Grace took in a deep breath through its mouth. That was something Humans do when they’re tired. Grace wasn't sure why, and it hadn't found a definitive answer about it on it thinking machines. 

"I'm going to sleep soon." 

"I watch." 

"Good night Rocky." 

"Good night Grace³." It didn't take long for Grace to drift off. I continued working on the power converter while it slumbered, seeming more restful than it had since I had known it. 

Despite what Grace had said about there being a long way to go, from Earth's perspective the work was actually done. It could turn its ship around and leave right now, with four years to test and refine its Taumoeba. I don't think that thought had ever occurred to Grace though. It didn't consider the work done until we had Taumoeba that could survive on Threeworld as well. 

Sometimes I had to marvel at the incredible unlikeliness of it all. Of being here at the right time to meet an alien species with advanced technology, here to solve the same problem as me. Of making a friend, light years away from anyone else in the universe. 

I still missed my crew terribly. They would have loved to meet this squishy alien. And Grace would have enjoyed meeting all of them. Although Mycelium's enthusiasm might have been a bit much for it. But missing them didn't hurt the same way it had before Grace arrived. There was a comfort that came with the pain, knowing that this journey wouldn't have been for nothing. I hoped it would also bring some comfort to their families. That conversation was going to be difficult. I still wasn't sure how I could justify being the only survivor to any of them. 

As Grace slept I let myself fall into the easy rhythm of work. It wasn't fair that I was the one here, but the universe wasn't dictated by fairness. Being fair was the work of people. I couldn't change what had happened, but I could honour the lives of my friends by completing our work. And I could help to ensure that what killed them would never harm another Eridian. Maybe that wouldn't be enough to balance the scale. Maybe nothing would. But that wasn't going to stop me from trying. 

Chapter Text

Time ticked by, second by second and hour by hour. Grace and I were both finding ways to occupy the time. Grace had started teaching me its alphabet, and like many things Humans do, it was incredibly inefficient. For some reason they use five letters to represent about 14 different sounds. Well, technically it's ten letters, but the other five are the same as the first five, just represented by different symbols. Like I said, inefficient.

It seemed like a lot of the language simply had to be memorised, rather than having the spelling directly related to the pronunciation. But the basics were easy enough to remember, and I was confident I could learn enough for our scholars to figure out the parts Grace didn't have time to teach me.

I finished the work on the laptop¹ life support system, and tested it very thoroughly before trying to put one of the machines in it. Grace had six of them, so it would probably be okay if one of them broke, but I preferred to get it working the first time and not waste one of the machines. Aside from the nitrogen resistant Taumoeba this would be the most important thing I brought back to Erid. If it broke, there was literally nothing I could do to fix it. That was a lot of pressure to get it right.

Grace wasn't sitting around doing nothing either. Aside from making its own preparations for the journey ahead, Its entire ship had to be sterilised from any possible Taumoeba infection. Purging the fuel lines wasn't too difficult, Grace just directed a high pressured stream of nitrogen down them, but the fuel tanks were too large for that. Instead Grace had to scrape each one of them down by hand, while wearing its space suit.

The tanks weren't made to be accessible, so I had built Grace a special Astrophage powered torch to cut its way into them. Don't worry, I had built safety features into it to help ensure Grace didn't cut off any of its arms. It created 1m² holes in each of the tanks to climb into, and removed any traces of Taumoeba it could find. Then it patched up the holes with some patches I had designed for it. With all the patches that had been added during this missions the hull of the Hail Mary was going to be very different by the time it arrived back at Earth. Although given that all those patches were made of xenonite, it would probably be sturdier if anything.

Once it had fully cleaned out every tank, I provided it with a few kilograms of Astrophage to test them. If there was still any Taumoeba in them, it wouldn't take too long for the Taumoeba to consume it. And sure enough, two of the fuel bays were still infected. Which meant that Grace had to completely clean them out again.

Then again.

And again.

I was working aboard my ship when I heard the distant sound of a fuel bay being ejected from the Hail Mary. It was a little alarming to hear a large piece of a ship suddenly detach and float off into space, but I knew the Hail Mary was designed to do that. Grace must not have been able to get bay 5 clean in the end.

I was working on a couple of projects of my own. One of them was the fuel injection system, to transfer fuel from my ship to Grace's. Getting the fuel into Grace's ship wasn't really a problem; The ship already had a port for fuel, I just needed to make something that fit into it. It was pumping it out of my ship that took more work. The fuel port of my ship had pretty much been designed to prevent fuel from coming out of it. To get past those safety measures I needed to design something that would reach all the way into the fuel tank, with a pump system to draw it out and into Grace's ship.

At the same time I was planning out how I would shield my ship from radiation during the journey back. The workshop would be safe, the Astrophage in the tanks surrounding the room would protect it. But I couldn't spend all three years of the journey back in the workshop. And while I had survived the journey here without more protection, I wasn't willing to gamble on that again. Not when I was carrying such vital cargo.

The Hail Mary was protected by a thin layer of Astrophage that lined the entire hull of the ship. It was an elegant system, but not one that I could use. The ship didn't have a lining that I could fill with Astrophage, and I couldn't exactly add one now. There were other methods Humans used to shield ships, but none of them perfectly blocked radiation. The Humans might be able to get away with that, but a survivable amount of radiation for a Human would probably kill me. And possibly the Taumoeba too, since I didn't know how they fared against radiation.

The best compromise I could think of for now was to create smaller enclosures on the ship lined with Astrophage. It would limit the accessible space, but that was a trade off I was willing to make if it kept me alive. And I would have three years during the journey to expand and improve on the system. For now it was just a matter of reinforcing the most crucial areas. I wanted to get that done before I left Tau Ceti's magnetic field, which according to Grace was deflecting a lot of radiation.

Speaking of Grace, it was making some angry growly noises in its control room. I'd gotten into the habit of leaving my workshop door open when I was working in my ship, so that the sound dampening wouldn't keep me from hearing Grace. Clearly it was unhappy about something. I put down what I was doing, and went to investigate. My tunnel connected my workshop to the enclosure in Grace's dormitory, so I had go through there and climb to my bulb in the control room.

Grace was in its seat, with its arms folded in front of itself. It was also pressed into the back of the seat, which it had to be doing on purpose since that wouldn't naturally happen in zero G.

"You make angry sound. Why?"

"I'm missing a third of my fuel bays. The trip home will take more time than I have food."

I listened closely to Grace. The physical signs of sleep deprivation were too subtle for me to pick up on most of the time, but I had gotten good at recognising the behavioural ones. Other than declining brain function, Grace also go clumsier the longer it was awake, and its emotional state got more fragile. What I was looking at now was a classic case of "sleep deprived Grace".

"How long since last sleep?" I asked it.

"Huh? I'm talking about fuel here! Stay focused!" It snapped.

"Grumpy. Angry. Stupid. How long since last sleep?"

Grace shrugged dismissively. "I don't know. I've been working on the breeder tanks and fuel bays... I forget when I last slept."

"You sleep. I watch." That irritated Grace. It waved a hand emphatically at its screen, having apparently forgotten that I couldn't hear what was on it without my camera, which wasn't turned on just then. Yeah, it definitely needed sleep.

"I have a serious problem! I don't have enough fuel storage to survive the trip home! It's 600,000 kilograms of fuel. It would take 135 cubic metres of storage! I don't have that much space!"

I patiently reminded myself that Grace was not its best self when it was tired. "I make storage tank." I told it.

"You don't have enough xenonite for that!"

"Don't need xenonite. Any strong material will do. Have much metal aboard my ship. Melt, shape, make tank for you."

Grace took a moment to process that information. A long moment. "You can do that?"

"Obvious I can do that!" I exclaimed, reaching the end of my patience. "You are stupid right now. You sleep. I watch and also design replacement tank. Agree?" I started towards the dormitory, but Grace did not immediately follow.

"Huh..."

"Agree?" I called again, a little louder.

"Yeah... Yeah okay..." Grace finally started moving toward the dormitory. With all the work we had both had to do I had been getting lax with monitoring its sleep schedule. One would think that having evolved with brains that required sleep to function optimally, Humans would also have evolved the ability to recognise when they needed to sleep, but Grace seemed to lack this. No Eridian I knew would allow itself to reach the end of a wake cycle without reaching a secure place to sleep with someone to watch them. But Grace would work itself past the point of exhaustion and not even realise that it had happened.

Okay, I was being harsh. It was probably difficult to tell that your brain was slowing down when you had to use your slowed down brain to do it. Normally there would be other Humans around to notice and alert Grace to the problem, but here there was only me. And as hard as I tried to support Grace, there was still a lot about Humans that I just didn't understand.

Grace climbed into its nest, and secured itself in place with the blanket. I settled down and picked up a notepad to begin planning out Grace's replacement tanks. When it was fully rested I would ask Grace to provide me with one of the remaining fuel bays, so I could get the proper measurements. But I knew the basic shape, and I could start figuring out the most efficient overall design.

"I'm sorry I snapped at you." Grace said from its nest. It had turned its head to face me, watching me make notes. I kept working while I answered:

"Is okay. You are grumpy when you not sleep." Grace laughed at that.

"Yeah. I guess I'm just worried, you know? We're so close now, all the way up to Taumoeba-70.5. It almost feels like it can't be real, you know?"

"Yes. Understand." I said softly. I really did. "Will be okay. Plan is working. We are brave, take Taumoeba home, save everyone. Will be okay."

Grace was quiet for a long while. I knew it wasn't asleep because its eyes were still uncovered, though it turned its head to face up at what would be the ceiling if there was gravity. I didn't interrupt it, I just carried on with my notes while it worked through whatever was happening in its brain. Finally, in the quietest voice I'd ever heard it use, it said;

"Would you still be my friend if I wasn't brave?"

"Not understand." I said.

"If I wasn't brave like you. If I was just a coward who didn't want to be here. Would you still want to be my friend?" I put down my notepad and pulled myself closer to the enclosure wall. I wasn't sure what conversation we were having yet, but it felt like one that needed my full attention.

"What you mean?" Grace didn't turn to face me, it just kept watching the ceiling. It took a while for it to find its next words.

"I didn't decide to come here. I didn't want to come here. It was supposed to be someone else, but they died. So they sent me instead." Water started pooling in Grace's eyes. There was no gravity to pull it down, so it just coated its eyes instead. Grace didn't try to wipe it away. It was gripping its blankets so tightly that its hands were shaking. "I didn't want to come. I was afraid. I knew the whole planet was in danger, I knew they needed me to help save it but-" Its words cut off with an ugly sounding breath, and the water spilled out of its eyes in little globules that floated just by its head. "I was scared. I didn't want to die out here. They had to make me come."

Silence stretched between us for a long moment. I had no idea what to say to that. What was I supposed to say to that?

The worst part was that I could see the mathematics of it. Billions of lives- no, far more than that. Trillions of animals and plants, probably most of the bacteria as well. An extinction event more catastrophic than any in their planet's history. All of that weighed against the murder of one person. Would our people have been willing to do that, if it had been necessary? Would I? I didn't know if I had an answer for that.

"Sad." I said finally, and immediately felt like an idiot.

"I'm sorry." Grace said, "I'm sorry I'm not who you thought I was. I'm sorry one of the better Humans didn't survive to do this with you."

I couldn't help it. I laughed.

That got Grace to turn its head back to me. It tried to wipe away all the water in its eyes and ended up smearing it all over its face. I could tell it was confused by my reaction.

"Sorry" I said, "Not funny, just- I not best Eridian. Not best Eridian for science. Not best Eridian for meeting people. Not best Eridian for most thing. Much, much better Eridians all die."

"Hey, don't talk like that. You're great. You're an amazing engineer. You're smart, you're brave, you- you're a great Eridian. You're a great person. I was so lucky to get to meet you."

"Thank. Maybe. Maybe not. I am Eridian who is here. You are Human who is here." I struggled for a moment to think of how to say what I wanted. We had spent so much time teaching each other many words for science, and very few for anything else. I needed words for other things right now.

"I not know what happen before. What kind of Grace you were before. Grace I know now do everything to help Earth. Do everything to help me. Do many scary thing; Go out in space. Put self in danger. Trust strange person very far away from home.

"Grace I know is brave. It okay if you not brave before. It okay if you afraid now. Be afraid and be brave is most brave. You are very important friend. Not want to not be friends because you afraid."

Grace was quiet again for a long while. "You think so?" It said finally.

"I know. You are brave. And you are friend. And- And am glad you are one here." I rethought that statement. "Not glad they send you to die, I mean. But I not always good at social things. Not good at making friends. Was afraid I would not make friends with alien. But you are easy to be friends with."

That made more water well up in Grace's eyes. "Thank you Rocky. Really, for everything. And I meant what I said, I'm lucky I met you. I don't think I could have done any of this without your help."

"Thank. But still sad that better Eridian could not help you."

"You are not a worse Eridian." Grace said very firmly, "You kept going after you lost everything. You kept looking for an answer, even after you failed. You took a chance on an alien you didn't know, and you risked your life to keep me alive and help Earth. I was so lucky that you were here. Erid is so lucky that you're here."

This had already been an emotional conversation, and that was almost too much to bear. It wasn't that I had ever thought I deserved to die. But I'd never really considered that maybe I deserved to live. That maybe I didn't have to make up for being me, and being here when everyone else was gone. I didn't think I was ready to really believe that. But I could feel the idea sitting in me now, ready for whenever I was ready to examine it. It was scary. And comforting. And really, really scary. But it was okay to be afraid.

"Thank." I said quietly. I raised my hand to touch the wall, and Grace reached over from its nest to rest its fingers on the same spot. "We breed Taumoeba. We go home. We keep being brave."

"Yeah." Grace said. Its face was still wet, but it was smiling just a little bit. "We keep being brave."

"Good. Now go to sleep. Not need brave and stupid Grace."

Grace laughed, and leaked some more, and then eventually its breathing slowed and it let itself drift into sleep. I stayed there at the partition for a while longer, listening to the rise and fall of its breathing. It was hard to imagine Grace refusing to join the mission. Hard to imagine it being willing to trade the life of every other Human for its own. It didn't fit together with the Grace that I knew.

Maybe knowing that should have changed my opinion of it. But while I had learnt that time could stretch and distort, it still only went forward. Maybe there had been a Grace that was a coward. Maybe there had been a Grace that cared more about itself than the rest of the world. But I had never met that Grace, I only knew this one. And I was very, very thankful for it.

***

"Installing final fuel bay now."

I wriggled and fidgeted as I waited. Grace had been outside for six hours. I was, of course, concerned for its safety as always. But that concern had taken a back seat to impatience and anticipation.

Designing new fuel storage for Grace hadn't been difficult. I had gotten Grace to detach one of the remaining fuel bays and hand it to my hull robot, which I used to take some measurements. Modelling replacements had been pretty simple after that. In fact, I had found some inefficiencies in the old design, and the replacements would be able to hold slightly more fuel. I had had to get a little creative with materials though. I didn't have enough of any one material on the ship to make the fuel tanks, so I ended up melting several metals together.

It was mostly iron, but it was anyone's guess what the exact ratios were. The point was it was strong enough to hold the fuel. Beyond that its properties were irrelevant. But I didn't care about the fuel bays right then. And waiting for Grace to finish with them and get back to the ship was agony.

"You are slow." I complained, bounding around in my control room bulb.

"You are mean." Grace retorted, with no real anger in its voice. I heard a lot of rattling and clanking through the ship as it fit the bay in place.

"Apologies. I am excited. Breeder Tanks Nine and Ten!"

"Yeah. Fingers crossed." That was another Human idiom. It just meant it was hoping for something good. I would cross all fifteen of my fingers if that's what it took.

In the previous generation we had successfully bred Taumoeba-78, and our current spacing was 0.25. Which meant that for the very first time we were testing Taumoeba in nitrogen levels equivalent to Planet Three. Tanks Nine and Ten had the potential of breeding Taumoeba that would survive in its atmosphere.

I tried to contain myself as Grace worked. This was a process, I reminded myself. Just because we were testing it didn't mean we would get a positive result immediately. It might take a few more generations before it could tolerate those nitrogen levels. But it was impossible not to hope.

The final tank took another three hours to install. I spent the time nervously fake-pacing around the tunnels, stopping in the lab frequently watch the tanks as if I had anyway to tell what was happening in there. By the time Grace cycled through the airlock I was a mess of nerves, but I tried to be mindful of the very strenuous work Grace had just done.

"It went well?" I asked. Grace held out a hand in front of it and wiggled it back and forth. That gesture actually meant that exact same thing in Grace's culture that it does in mine. We were both surprised and amused to discover that accidental overlap.

"Maybe. I'm not sure. A bunch of the bolt holes were unusable. So the bays aren't as well connected as they should be."

"Danger? You ship accelerate at 15 metres per second per second. Will tanks hold?"

"I'm not sure. Earth engineers often double requirements for safety. I hope they did this time. But I will test to be sure."

That was a sensible practice. And I should make sure to run those tests with Grace. If anything was in danger of breaking I wanted to know before we left the system. But that was a later problem.

"Good good. Enough talk. Check breeder tanks please."

"Yeah, yeah. Let me get some water first." I scrambled along the tunnel to the lab. I had begun to suspect that that reason Humans were so shameless about eating in front of each other was because they had to do it so constantly that there was no time to do it in private.

"Why Humans need water so much? Inefficient life forms!" Grace consumed an entire bag of water it had left in the control room before making it own way to the lab.

"Eridians need water too, you know."

"We keep inside. Closed system. Some inefficiencies inside, but we get all water we need from food. Humans leak! Gross."

Grace laughed as it entered the room. "On Earth, we have a scary deadly creature called a spider. You look like one of those, just so you know."

"Good. Proud. I am scary space monster. You are leaky space blob." I pointed emphatically at the waiting tanks. "Check tanks!"

Grace finally pushed itself towards the tanks. In a moment of uncharacteristic mercy it didn't make me wait while it checked every single tank. It move directly to tank Nine, the one with 8% nitrogen concentration. The one with Planet Three's nitrogen levels. Suddenly I fell very still as it pulled out the Astrophage slide, and checked the reading on the tank.

The Grace's mouth stretched in a wide smile.

"Tank Nine's slide is clear. We have Taumoeba-80!"

I erupted. I was an uncontrolled, shrieking mess. Everything that had built up inside me, all the years of grief, despair, and frustration, all the pain and anxiety, all the excitement of working with Grace, all of it finally found a release in a moment of pure ecstatic relief. My arms flailed, my hands struck chaotically against the walls. I was making pure, unfiltered noise like an infant.

For a few seconds I just let myself feel all of it. Then I slowly pulled myself back together enough to speak.

"Yes! Good! Good good good!"

"Ha-ha, wow. Okay. Easy there." Grace said, but it was smiling so wide it looked like it was going to split its head in half. It checked on Tank Ten. "Hey, Tank Ten is also clear! We have Taumoeba 82.5!"

"Good good good!"

"Good good good indeed!"

"Now you do much testing. Venus air. Planet Three air." I said, still giddy from the sheer joy of it all.

"Yes. Absolutely-" I was barely listening. I was bouncing around my tunnel, unable to stay still.

"Exact same gases in each test. Same pressure. Same temperature. Same death 'radiation' from space. Same light from nearby stars. Same same same."

"Yes. I'll do that. I'll do all of that."

"Do now."

"I need rest! I just did an eight-hour EVA!"

Grace was absolutely right of course. It had just spent a very long time doing very physically taxing work. Human needed rest after that kind of exertion, or they could exhaust or even hurt themselves. It was very unreasonable to expect Grace to do any more work right now.

"Do now!" I insisted. I felt like I'd earned at least a little bit of being unreasonable.

"Ugh! No!" Grace pushed itself so that it floated to my tunnel and faced me. "First I'm going to breed up a bunch more Taumoeba-82.5. Just to make sure we have enough for testing. And I'll make several stable colonies of it in sealed containers."

"Yes! And some on my ship too!"

"Yes. The more back ups the better." I bounced around the tunnel some more. My carapace felt like it could shake apart from all the energy built up in it.

"Erid will live! Earth will live! Everyone live!" I curled one hand into a fist and placed it against the tunnel wall. "Fist me!"

Grace mimicked the gesture. "It's 'fist-bump', but yeah." I made a mental note that the specific wording was important for this gesture, but it was hard to care about that right now.

Grace went to get some rest before beginning work, and I headed back to my ship so I had more space for bouncing around. We did it. We had DONE it. I was going home. I had the answer to save my planet, and I was going home.

I was going home.

***

It had been a long time since I'd worn my gloves. They weren't exactly practical, I couldn't use many of my tools effectively while wearing them. But this was not about practicality. It was about celebration.

I was waiting in the lab tunnel for Grace to arrive, and fidgeting gently in place. It was looking for something in the dormitory, claiming it needed it for the celebration. It finally located it, and emerged through the hatch into the lab.

"Found it!" It said, holding some kind of liquid-filled bag, much like the ones it consumed water from.

"Good good." Grace turned its head to me, and noticed my clothing for the first time.

"Well, well, well! What have we here?" It said with a smile. I jutted out my carapace pridefully. I deserved a little pride, just this once. "You look great!"

"Thank! This is special clothing for celebration!" The outfit was extremely extravagant. The underneath was simple cloth, but it was layered in scales of Plantic². It had sleeves that reached down to the elbow of each arm, and braided cords that ran between each shoulder. Each cuff, and the hole that exposed my radiator, was ringed in gems. They were beautiful sounding things, I had picked out ones I liked myself. They gave a slight crystalline ring to every sound in the room.

The last time I had worn this was when we were leaving Erid. The entire crew had been dressed up, to show our pride in what we had been asked to do. I had worried I might never have a reason to wear it again.

Grace wasn't wearing anything different to usual, but it lifted up its bag of liquid. "This is special liquid for celebration!" It said.

"Humans... eat to celebrate?"

"Yeah. I know Eridians eat in private. I know you think it's gross to see. But this is how Humans celebrate."

"Is okay. Eat! We celebrate!" This was a big moment for both of us. I wasn't going to ruin it for Grace by telling it it couldn't have its special celebration liquid. Besides, I had gotten somewhat desensitised to Grace eating at this point. I could put up with it for this.

Grace floated over to two tanks that had been mounted on the lab table. The tanks contained two different atmospheres; one equivalent to Venus, the other equivalent to Planet Three. Grace had painstakingly recreated conditions as exactly as it could, using the data from its ship and my own knowledge of Planet Three. The results were clear: The experiments had been a complete success.

The new nitrogen resistant Taumoeba had thrived in their new environments. They reproduced just as quickly as the original strain did in normal conditions, devouring Astrophage as they went.

Grace raised its bag of liquid higher. "To Taumoeba-82.5! Saviour of two worlds!"

"You will give that liquid to the Taumoeba?" That seemed like a bad idea. We did have more of it, Grace had established stable colonies on both of our ships for safety. But I still didn't think we should kill these ones off for celebratory purposes.

"No, it's just a thing Humans say. I am honouring Taumoeba-82.5." It ingested a small amount from the bag, and its face scrunched up. Apparently the special celebration liquid caused some kind of discomfort. I wondered if that was a normal part of Human celebrations.

"Yes. Much honouring! Human and Eridian work together, save everyone!"

"Ah! That remind me: I need a life support system for Taumoeba- something that feeds them just enough Astrophage to keep the colony alive. It has to be completely automatic, has to work on its own for several years, and it has to weigh less than a kilogram. I need four of them."

"Why so small?"

"I'm going to put one on each beetle. Just in case something happens to the Hail Mary on the way home."I didn't like to think that that might happen. But space was dangerous, we both knew that. Preparing for the worst was a sensible precaution. I shoved my concern to the side for now.

"Good plan! You are smart! I can make these for you. Also, today I finish fuel-transfer device. Can give you Astrophage. Then we both go home!"

"Yeah" Grace said. The smile it had been wearing up this moment slipped away.

"This is happy! Your mouth is in sad mode. Why?"

"Going to be a long trip and I'll be all alone." Grace said.

"You will miss me?" I asked, "I will miss you. You are friend."

"Yeah I'm going to miss you." Grace ingested more liquid, its face scrunching up again. I wasn't sure why Grace was celebrating with something that it didn't seem to be enjoying. Especially after the fuss it made about food experience. But there's no accounting for cultural norms. "You're my friend. Heck, you're my best friend. And soon we're going to say goodbye forever."

Grace's mood was becoming maudlin, which was the opposite of what we were meant to be doing. I tapped two fingers together dismissively. It didn't click, because I was wearing gloves, but it got the point across.

"Not forever." I said. "We save planets. Then we have Astrophage. Visit each other."

Grace did the smile that was not a proper smile. The one that folded its face in the wrong way for happiness. "Can we do all that within fifty Earth years?"

"Probably not. Why so fast?"

"I only have fifty years or so left to live. Humans don't-" Grace did a sharp intake of breath that didn't sound like any of its usual noises, and then continued "-don't live long, remember?"

"Oh." Right. Of course. Grace's life span was only approximately 80 years. I didn't know how I'd forgotten that. Humans were such brilliant things, but they burnt out so quickly.

I might see Earth someday. But Grace would be gone by the time I got there. This was really it for us. How strange and wonderful and cruel that someone could change your life so profoundly, and then be gone forever. But I didn't want to be sad now. I wanted to be glad for everything that we'd had.

"So we enjoy remaining time together," I said decisively, "Then we go save planets. Then we are heroes!"

"Yeah!" Grace straightened itself out. Its movements were a little clumsier than usual. That was strange, because I was sure it had had enough sleep. "We're the moss importn't people in the gal'xy! We're awesome!"

I grabbed a tool that I had left in the tunnel before, and raised it up. "To us!" I announced.

"To ush!" Grace repeated, raising its liquid.

***

It was a good celebration. Grace put its liquid away not long after that, and we spent the rest of its cycle talking and laughing, and playing Space Catan. Grace had gotten pretty good at it. We relived our adventures in Tau Ceti, shuddering at our close brushes with death, and laughing about how strange our species were to each other. The time passed quickly and before I knew it Grace had to sleep again. It was a shame it had to spend so much of its short life sleeping.

We spent the next few cycles making our final preparations. I built the miniature Taumoeba farms for Grace out of steel, rather than xenonite. I wanted the farms to be a single, solid piece so that there was no danger of leaking while in transit, which meant the Humans would need to cut them open when they got to Earth. Humans didn't have anything strong enough to cut through xenonite, but they had saws that would get through steel. Grace thought they would also be pleased to have steel from Erid to study, which was apparently stronger than the steel they made on Earth.

The fuel transferral went perfectly, and with the new tanks the Hail Mary was able to hold 2.2 million kilograms of fuel. I also ran a lot of tests on my laptop life-support device, which were all successful. When I finally felt confident to try it with an actual thinking machine in there it worked with no problems.

Untangling my ship from Grace's took some time. I was able to move my own things this time, through the tunnel I had built connecting the ships. Then I had to remove the tunnel, and patch the holes left behind. Grace asked me to leave most of the xenonite from my enclosures in place, and just cut holes into it so it could use the space. I was fine with that, it wasn't as though I could reuse that xenonite anyway. And it would be good material for the Human scientists to study.

And then there just wasn't any reason to still be there. It was time to go home.

"Well. This is it." Grace said. We were standing on either side of the airlock tunnel, the last remaining connection between my ship and Grace's.

"Yes." I replied. I tried to keep my voice up but it dipped low anyway. It was silly. Grace wasn't dying. Not right now, anyway. It was going to go home and live a good life in the world it had helped to protect. So was I. It was a good thing, and I was very happy to be going home. But that didn't cancel out the grief.

Grace rubbed the back of its head. I assume our people will meet up again. I know Humans will want to learn all about Erid."

"Yes. Thank you for laptop. Centuries of Human technology all for our scientists to learn about. You have given greatest gift in history of my people." The laptop wasn't really the greatest gift Grace had given my people. It wasn't the greatest gift it had given me. But I at least knew how to thank it for the machine.

"You tested it in that life-support machine you built for it, right?"

"Yes. That is stupid question." Grace had been there for a lot of the tests, to help confirm the laptop was functioning correctly. I was going to miss Grace's stupid questions.

"And your farms? You double checked them all?"

"Yes. Six redundant Taumoeba-82.5 colonies, each in separate tanks with separate life-support systems. Each with Planet Three simulated atmosphere. Your farms are functioning?"

"Yeah. Well, it's just my ten breeder tanks. But now I have them all set up with Venus's atmosphere. Oh, and thanks for the mini-farms by the way. I'll install them in the beetles during my trip. I won't have much else to do."

I resisted the urge to offer to do that for Grace. Grace was not an engineer, but it could manage that on its own. I had already given it my thoughts on and advice on attachment. What I really wanted was a reason to hang on a little longer, and that wasn't an option. We couldn't stay forever, that would kind of defeat the purpose.

I turned my attention briefly to a notepad floating in the tunnel next to me. It was imprinted with some numbers that Grace had worked out for me. I had wanted to be very, very sure I remembered them all correctly, so I'd made a point of noting them down.

"These numbers you gave me. You are certain these are the times for me to turn around and the times for me to reach Erid? They are so soon. So fast."

"Yeah, that's time dilation for you. Weird stuff. But those are the correct values. I checked them four times. You'll reach Erid in under three Earth years."

"But Earth is almost same distance from Tau Ceti, and you will take four years?"

"I'll experience four years, yes. Three years and nine months. Because time won't be as compressed for me as it is for you."

"You have explained before but again... why?"

"Your ship accelerates faster than mine. You'll be moving closer to the speed of light." I wriggled in frustration. No matter how often Grace explained it, it never seemed any less unintuitive. This wasn't physics as I understood it. But I trusted Grace's science.

"So complicated." Grace gestured towards my ship.

"All the information about relativity is in the laptop. Have your scientists take a look."

"Yes. They will be very pleased."

"Not when they find out about quantum physics. Then they'll be really annoyed."

"Not understand."

Grace laughed. "Don't worry about it."

We were quiet for a while. It was time to leave. I wasn't ready to say goodbye to Grace. I don't think Grace was either. But I didn't think either of us were ever going to be ready. We'd just have to do it while we weren't.

"I guess this is it."

"It is time. We go save homeworlds now."

"Yeah."

"You face is leaking." Water was coating Grace's eyes again, floating off in little globules. Grace rubbed at them.

"Human thing. Don't worry about it."

"Understand." I steeled my resolve and pushed away from the wall to the airlock door. I allowed myself a final pause as I opened it. "Goodbye, friend Grace." I said. It gave me one final wave.

"Goodbye, friend Rocky."

I closed the door, and waited until Grace had fully cycled back into the Hail Mary before using the hull robot to apply solvent to the tunnel. I didn't want to leave the anchor in place; It would have spoiled the streamlining of Grace's ship. Apparently there was more in space than I knew of, and I didn't want any of it slowing Grace down. Then I used the robot twist the tunnel. After a moment of resistance it separated from our hulls, and Grace was gone. I knew it hadn't gone anywhere yet, we were both pretty much exactly where we had been a moment ago, but I couldn't hear it anymore. For me, Grace was gone.

Chapter Text

There was gravity again. Actual Erid levels of gravity. That was the acceleration we decided on when we built the ship, something that we knew we could work in easily. It turned out that I didn't need to worry about it being unfamiliar, after few minutes of adjustment my body adapted to it like the most natural thing in the universe. I wondered if that was what being home would be like; briefly disorienting, but innately familiar. I hoped so. I didn't like to think that being in space had become my normal.

The greatest adjustment, which was no real surprise, was not having Grace around. My cycles had become entirely entangled with Grace's, my schedule fit around its regular sleep, its need to eat through all hours of the cycle, its humming and theorising and occasional stupid activities. The ship was so quiet now without the sound of the Hail Mary and Grace attached to it. Even with the noise of the engine, it was so quiet. Somewhere along the way I realised I had stopped waking expecting to hear my crew. I didn't know when that had happened. It gave me a strange new kind of grief, as though I had left them behind somehow. Now it was Grace I found myself listening for, and it wasn't there either.

I know I'm making this sound very miserable, and I was very lonely. But I wasn't wallowing in despair. Unlike before, I knew this was temporary. I was on my way home. And as sad as I was that I would never see Grace again, I couldn't help but be excited too. Soon I would be speaking with other Eridians again, joining thrums, doing engineering, and just existing in places without walls. I was really, really looking forward to that.

Try as I might I couldn't help but speculate about Adrian. I wanted to see it again. I wanted to be part of its life again. But I didn't want to impose if it had moved on from me. I had decided a long time ago that I wouldn't resent it for that. It hurt to think of starting life again without it as my spouse, but if that was the price I had to pay to keep it and everyone else safe I would pay it.

Still. It was hard not to fantasize about coming home to find it waiting for me. About it clasping my hands tightly and welcoming me home. About falling asleep again with it watching over me while carving its rocks. But it wasn't fair to expect that. By the time I got to Erid it would have been almost 70 years since I left. I just hoped I could still be some part of whatever life it had made for itself in my absence.

Luckily there was enough to keep me busy. My ship had not stopped needing fairly frequent repairs, although all the critical systems seemed to be in good shape. Plus I had to tend to the Taumoeba, but that was mostly a matter of checking the readings on all the farms. If I was a scientists there was probably all sort of interesting experiments I could have run on them, but I was content with just keeping them alive.

I was keeping three of them in the engine room, where I knew the fuel tanks would shield them from any radiation. I would have kept them in the workshop, but frankly there wasn't very much space in there, and this way there was less chance of me damaging any of them while doing my work. There were also two in the lab and one in the control room, in special Astrophage-lined habitats I had built there.

The habitats were the best I'd been able to do on radiation shielding in the time I'd had. I had plans to try and expand on them during the journey, but I was going to be limited by the available materials. There simply wasn't enough xenonite to build them so I was just melting down and reshaping any metals I had around. It would do. At least I knew my workshop and the engine room were safe.

Oh, and I suppose I also had a thinking machine full of advanced alien science to peruse. Grace had filled it with as much information as it could store, which was quite a lot. Thinking machines were really incredible. I still wasn't all that fluent in written English yet, but Grace had taught me enough that I could work out some more of it on my own. Plus it had shown me a handy function called "text-to-speech". It wasn't perfect, and it took a while to get used to the new voice, but it was handy for speeding up my learning. I understood a lot more of spoken English than written.

A lot of the science didn't make sense to me. But there was also a lot of information about Earth technology, which I was very interested in. I tried not to play around with the machine too much, because I didn't want to wear it out. Grace had shown me a document that had a lot of information about the machine's specifications and how to take care of it. There still wasn't anything I could if the components broke, but it was a useful guide for how to maintain it in other ways. Hopefully I could keep it functioning for a long time. At least until my people were able to make contact with Earth again, in the future.

So I was in pretty good spirits, all things considered. It would be a lonely three years, but it would only be three years. And I had a lot of work and interesting study to keep me occupied in the meantime.

That attitude lasted until about ten cycles into the journey, when I realised that everything had gone horrifyingly wrong.

I had decided to start designing a probe to deliver the Taumoeba to Planet Three. Technically I didn't really need to do this part; When I got back to Erid there would be plenty of time for the engineers there to design and launch their own system. But it would be more efficient for me to deliver the Taumoeba myself, before I returned to Erid. I already had all the necessary information about Planet Three and the Taumoeba, and enough material on my ship to make the necessary mechanisms.

Of course, I would need to contact the observatory before I could launch anything to Planet Three. I was confident in the solution Grace and I had found, but I wasn't going to infect the planet with a new life form without getting approval from the science hives first. They might prefer for me to land so they could study my findings first, in which case this work would have been entirely unnecessary. But I wanted to do it anyway. If they agreed to it it would save a lot of time and an additional space mission.

The design was something similar to the probe I had made to gather that atmosphere sample at Adrian. But where that one was designed to seal when it reached the Astrophage breeding altitude, this one was designed to open and disperse the contents. It would also need to be capable of surviving being dropped into the atmosphere. I was not planning to carefully lower this one on a chain while maintaining sub-orbital speeds.

It made the most sense to create some kind of cooling system with the Astrophage. That should keep the probe from melting, and protect the Taumoeba long enough for the probe to reach the correct altitude. Conceptually it was quite similar to the system that protected Grace's ship from heat, but hopefully without the part where it got overwhelmed and failed.

I was building a prototype to test how quickly the conduits would draw away heat when I dropped one of my tools. I'm not generally clumsy, but it happens to everyone occasionally. But something about dropping the tool bothered me. Or, no, dropping the tool didn't bother me. The tool falling bothered me. Why? What was wrong with the tool falling?

The tool was just a normal iron wrench. It hadn't taken any damage while falling, and it hadn't damaged anything else. I picked it up and dropped it again, experimentally. The little niggling feeling I had intensified. That wasn't right. I picked it up again, holding it higher this time, and dropped it. This time I was certain; the wrench was falling too slowly. The engines were at full thrust, so a falling object should accelerate at 20.48m/s². That couldn't have been more than 17m/s². But the only way that was possible was if the ship was accelerating slower that it was meant to.

Okay. There was no need to panic. Part of me protested that actually there was a lot of reason to panic, if something was wrong with the engines. But I kept that part under control. I could handle faulty engines. In fact, of all the disasters I had encountered recently faulty engines was the one thing I was actually qualified to address. It made a nice change of pace from esoteric science problems. I put away and secured down everything I had been using and headed for a door at the back of my workshop that led into the engines room.

Grace had explained the Hail Mary's spin drives to me once. With no one conscious to look after them, the Humans had prioritised redundancy in the system. Rather than one or a few thrusters, they had made 1,009 very small spin drives that worked together. If any of them failed the others would simply increase their power to compensate. It was a very elegant solution to the problem.  But our ship had been designed knowing an engineer would be aboard to address any mechanical issues. The priority for us had been making things accessible and repairable. The ship was powered by four large thrusters that could retract fully into the ship for servicing.

I spent the next few hours thoroughly checking the thrusters for any faults. I shut down and retracted two at a time, leaving the other two thrusting so I could keep working in gravity. I checked every wire, every fuel line, every IR emitter, and I did not find a single issue with any of them. The fuel was transferring at the correct rate, and the thruster was operating correctly. It just wasn't getting the thrust that it should be.

The good news was that while I was still in gravity I could at least pace properly while I considered the issue. The bad new was that no matter how I thought about it it just didn't make any sense. I had had issues with generating thrust on the way to Tau Ceti, but I didn't think this was the same thing. Grace had explained that that was caused by the ship being unable to exceed the speed of light. It had done an enormous amount of maths and calculated exactly how long into the journey I would need to keep thrusting for before reaching that limit. It had checked the numbers four times. And even if I doubted the numbers this was much sooner than it had happened last time.

It didn't make sense. The power generated by the thrusters was directly proportional to the amount of fuel being used. All of my checks confirmed that the correct amount of fuel was being drawn from the tanks and the engine was using it correctly. It simply wasn't generating the expected amount of thrust from it, which wasn't possible unless-

Unless not all of it was fuel.

I stopped mid-step, my body suddenly tense with fear. No. No no no no. That wasn't possible. That was not possible.

Fighting against a new rising panic, I scurried back to my workshop and grabbed some syringes. Then I brought them back to the engine room, and used one to draw a sample from one of the fuel tanks. There were sixteen in total, surrounding the engine room. Five of them were empty, having supplied the fuel for the journey here, and then for Grace's own journey home. They were fully separated from each other, and the ship was designed to draw from one of them at a time. The one I sampled from was the one currently in use.

I drew out a precise volume of Astrophage from the fuel tank. Then I headed to the lab, and drew at the same volume from my Astrophage-lined habitat. Then I brought both samples to my workshop, and began setting up some temperature measuring apparatus.

Theoretically both samples should contain the same number of Astrophage. Following from that, they should be outputting the same amount of heat. Grace had used a system like this to measure the Astrophage population of the first sample we took from Adrian, and it was a very reliable method. I was very tense as I set the samples up in the temperature measuring apparatus, and waited for the results.

The results were bad. The results were really, really, really bad. The sample I had from the fuel tank was reading at a significantly lower temperature than the sample from the fuel tank. Too much lower to be accounted for by natural population variance. Which meant that this volume contained fewer Astrophage than the volume from the habitat. And there was only one thing I could think of that would explain that.

There were Taumoeba in the fuel tanks. And they were eating my fuel.

For a minute all I could do was stand there in shock. My mind was a furious storm of questions; How had this happened? Was it in all the fuel tanks, or just this one? How long did I have before the fuel was gone? How had this happened?

No, there wasn't time for that. If this was happening, there wasn't time to panic. I ran back to the engine room, and set the thrusters to shut down completely. The fuel tanks were all completely sealed- or they were supposed to be, anyway- only opening when fuel was being passed to the engines. If this fuel tank was contaminated I wanted it completely shut down while I figured out the extent of the problem.

The floor fell away from me as gravity disappeared. Long, long ago, when I had first experienced true weightlessness, the feeling had been terrifying. I thought I had been prepared for it, but the fear of falling is a very hard wired one. Now I barely noticed it as I scrambled to get to work.

I grabbed a bunch more syringes, and began taking samples from the other ten tanks that still contained fuel, plus one from the generator. The tanks were all fully sealed and separated from each other and the generator had its own separate fuel supply it drew from, so in theory none of the other tanks should be contaminated. But then, the first tank shouldn't have been either. There had been a lot of loose Taumoeba on Grace's ship, but even if some of them had made it into my partition and onto my ship the atmosphere would be too hot for them to survive. The only Taumoeba I had brought aboard were in sealed containers, maintained at survivable temperatures. So to get into my fuel tanks the Taumoeba would have to:

1) Escape from the fully sealed xenonite farms

2) Somehow survive in an atmosphere over 100^oC hotter than its highest temperature limit

3) Enter a fully sealed xenonite fuel tank.

It didn't make sense. But now I had to answer an incredibly urgent question: Had something broken enough to let this happen? Or was there some kind of fundamental design flaw in both the fuel tanks and the breeding farms? If it was the former, then I would need to identify and repair the breakage, and sterilise the ship. But it was nothing I couldn't handle.

I held onto that hope for a few precious minutes as I set up the samples and waited for the reading. Then I got the results. Of all eleven samples, only those from two of the tanks and the one from the generator were reading at the same temperature as the habitat sample. Every other tank was contaminated with Taumoeba. It was actually worse than that; The first tank I had sampled from was one of the least affected. Some of the others were reading at barely a quarter of the temperature.

My hands were shaking. Actually, it wasn't just my hands I realised. My whole body was trembling. I grabbed tightly onto handrails with all five hands and just tried to calm myself down. This couldn't be happening. How could this be happening? The breeding farms were fully sealed, I tested them. And how had they spread through so many of the tanks? They weren't connected at all, they were even fueled through separate inputs.

No, no. I couldn't do this. I couldn't stay here paralysed. Somehow I had to contain this. I had to stop it from getting to the last two tanks of fuel. I had to try and recover what I could from the contaminated tanks. A rational part of me objected that that wasn't possible, but I ignored it. It didn't matter if it was possible, I had to do it.

Nitrogen. I needed nitrogen. This strain of Taumoeba could survive an 8.25% concentration at 0.02 atmospheres, but it would still be very easy to overwhelm. I wasn't carrying elemental N₂, but my atmosphere was a nitrogen compound. I could separate the nitrogen out from the hydrogen and use that. That was going to take some time. I didn't have any time. But it wasn't as if I could materialise everything I needed from nothing.

Pushing aside my panic, I began putting together the equipment I needed to harvest the nitrogen. At the same time, I was trying to analyse the situation and figure out what had happened. The pattern of temperatures from the tanks wasn't random; The most affected tanks were those directly touching the Taumoeba farms. I had situated them in a corner, pressed right against the thanks to maximise their protection from radiation. The three thanks forming that corner showed the lowest temperatures, and the readings rose as they moved away from them. The two potentially unaffected tanks were on the end furthest from the corner, separated from the tank I had been drawing from by the five empty tanks.

That told a very clear story of the spread, but it still didn't explain anything. The fuel tanks were not heated like the rest of the ship, and the Astrophage would keep the temperature around 96^oC, so once the Taumoeba got in they would have no problem in that environment. But how could they get from the farm to the tanks without dying in the 210^oC atmosphere of my ship? And how was it spreading between tanks? It was as though it had just passed directly through the xenonite-

I almost stopped in my tracks, but there really wasn't time to do that. Could the Taumoeba do that? Pass through the xenonite?

Most of the xenonite on the ship was as hot as the atmosphere. But the tanks were only 96^oC inside, and that farms were kept at -82^oC. The xenonite housing them would be a lot cooler, possibly cool enough for Taumoeba to survive. But that was presuming that the Taumoeba had the ability to pass through a solid surface, was was ridiculous.

Wasn't it?

The tanks touching the Taumoeba farms had been infected first, and had spread through to tanks separated by xenonite walls. The generator, which was sealed in its own compartment surrounded by normal temperature atmosphere, was unaffected. The habitat had been unaffected too, despite having the exact same kind of farm in it. But the habitat was made of an alloy, not from xenonite.

Well, actually, I didn't know for sure the habitat and generator were unaffected. They were reading at the same temperature as each other, and the two end tanks, which suggested it. But it could be that they were all in the very early stages of contamination, and not showing as much temperature drop as the others. Without having a sample I knew to be clean to compare them to I couldn't rule it out yet. I would need to take more samples at intervals to check if they were experiencing any kind of change.

For now I would move forward with the assumption that they were uncontaminated, because that was a lot less scary. It meant that I wouldn't lose my electrical systems, and that I still had a safe shelter from radiation. But I'd keep checking on them, just in case. I wanted to go move the farms away from the tanks, but I kept at what I was doing. If the Taumoeba was somehow passing through the xenonite, and that was a big if, the damage had been done. It was more important right now to get this part done and begin harvesting nitrogen to sterilise the ship.

It took an agonising hour to get the apparatus set up, and begin the separation process. I had two cannisters set up; One to collect the nitrogen, and one to collect the leftover hydrogen. The hydrogen was not of any particular danger to me, since my body didn't react to it. It was technically highly flammable, but it couldn't ignite without any oxygen. And while I had separated some from my carbon dioxide supplies previously there wasn't any of it left on the ship now. I had flushed it out before leaving, since I didn't need it and it was a fire hazard. Plus I really, really didn't want any on my ship. Yes, even after spending so many cycles aboard Hail Mary completely surrounded by the stuff I was still a little nervous about oxygen. Being on fire will do that to you.

Still, it seemed like a good idea not to leave random gases floating around in my atmosphere. Although there probably was still some of that. Separating compounds was a messy science, and I was in a rush so I hadn't built a foolproof containment system for it. But most of it was contained in the cannisters.

Thankfully I had more to do than waiting around. While I'd been working on the nitrogen separation equipment, I had also been planning out how to rescue as much of my fuel as possible. My priority was the two tanks that appeared unaffected so far. Keeping them from being contaminated would be a lot easier than trying to decontaminate the others. Two tanks of fuel wasn't enough to get me back to Erid on the planned timetable, but it would still get me there. It would mean spending a couple more years in space, but I could afford to do that with my current supplies.

So step 1: Moving the fuel.

Actually, Step 0: Moving the breeding farms. I stacked the three farms from the engine room into the lab habitat, which a second reading showed was maintaining the same temperature. Then:

Step 1: Moving the fuel. I wasn't prepared to commit to the idea that Taumoeba could spread through xenonite yet, but it was obvious that distance was a factor. I had five empty tanks, if I moved the fuel into those then I could create a buffer between them and the other tanks.

Luckily, I already mostly had a tool for this. The fuel injection device I had built for Grace would work just as well for transferring fuel between tanks on my ship. All I had to do was change the end designed to work on Grace's fuel port. While I worked on modifying that I also built three small heaters. My plan was to sterilise all five tanks with nitrogen, then use the heaters in the buffer tanks to make them as inhospitable as possible to the Taumoeba. I hoped that would created a hard barrier, to prevent them from crossing to the clean fuel.

The next few hours were a blur of activity. The moment I had enough to do so I flooded the empty fuel tanks with nitrogen. The fuel tanks weren't pressurised like the rest of the ship, so all I had to do was drill in a small hole, feed in the nitrogen, and seal it again. I wasn't sure what exact quantities I was using but it would be more than enough to kill any Taumoeba floating around inside.

I installed the heaters in the first, middle, and fifth tanks. They were designed as small boxes with a rod containing all the heating apparatus attached. I inserted the rod into the hole I'd drilled for the nitrogen. The box sat on the outside, providing all the electricity, and the rod sealed the hole while heating the interior to 200^oC.

Every second I was working I could feel time slipping away from me. Population growth is an exponential process: the more Taumoeba there was, the faster their population would grow. And the faster the population grew, the higher the probability that they would move into the unaffected areas. It felt like I was moving in slow motion, even as my arms worked in a blur.

Finally I was able to hand the fuel injection device to the hull robot, and begin moving the fuel into the steralised tanks. All the fuel ports were on the outside of the ship, so I couldn't access them myself. When we'd designed it we hadn't expected that we might need to remove or move around any of the fuel. My whole body was buzzing with anxiety as I began the transfer. The latest reading showed that the temperature was holding steady, so there was still hope. Even if I had to spend a few extra years getting to Erid, at least I would get there.

The next big question was whether any of the rest of the fuel was salvageable. The three tanks from the corner touching the farms were probably a lost cause, but my latest readings showed that a couple of the furthest tanks were emitting as much as 80% of full heat. At least four others were still reading above 50%. Anything I could recover would reduce the amount of time I had to spend in space. But separating out the still living Astrophage from the Taumoeba was a challenging proposition.

When it had been studying the Taumoeba, Grace had compared it to an infection. On Erid the fatality rate from infections was incredibly high, even with immediate medical intervention. But on Earth they had developed medicines by finding life forms that killed the infecting bacteria without harming the surrounding cells. I knew of multiple things that could kill Taumoeba without harming Astrophage. Nitrogen, heat, and true vacuum were all deadly to it. I couldn't reliably create a vacuum, since any dead Astrophage would release carbon dioxide. But nitrogen and heat were readily available to me.

The main problem was, ironically, the Astrophage. The Astrophage would absorb any heat above 96^oC, protecting the Taumoeba. And any nitrogen I used would be useless against Taumoeba hidden under a layer of Astrophage. But if I could force all the Astrophage and Taumoeba to pass through a small enough tube- and I talking about microscopically small tubing- then the Taumoeba might not be able to hide behind the Astrophage. I could heat the tube to temperatures that would be deadly to the Taumoeba, killing it as it passed through. And I could feed the tubes into a tank filled with nitrogen, to kill off any remaining Astrophage.

There were a lot of problems with that plan. First, it would take a lot of time. Even if I built a very large apparatus with a lot of microscopic tubing, passing even one tank of fuel through it would take a lot of time. And in the mean time the infection would be continuing to spread. Plus, where would I move the fuel to? I didn't have enough to maintain more buffers, so even if I could fully sterilise one of them it would be at risk of being infected by any contaminated tanks nearby.

But it wasn't like they'd be any more contaminated than they were already. At least if I tried there was a chance I could recover some extra fuel. Although it would be fuel full of dead Taumoeba, which was its own problem I would deal with later.

Which meant I had a lot more work to do. My whole body protested at the thought. I felt exhausted, even though my next sleep wasn't for hours. Hours of working while trying to keep yourself from panicking will do that to you. It was a good thing being tired didn't make me stupid like Grace, if I had to build all this equipment with my faculties impaired I-

My whole body froze in a new wave of terror. Grace. How had I not thought of it before? Grace had the exact same Taumoeba farms that I had, farms that the Taumoeba had escaped from. And although I had done a lot of work to repair its ship before we left, its fuel was the furthest thing from properly sealed. The Taumoeba would have no problem with its environment either, it had proven that already.

What if my crazy hypothesis was right? What if the Taumoeba could pass through xenonite? What would keep it from infecting and eating all of Grace's fuel? It only had enough fuel for the journey home, it couldn't afford to lose very much of it. I felt shaky. Grace could be stranded in space right now. That couldn't happen. I couldn't let that happen to Grace.

Calm down, I told myself. Try to calm down. Maybe I could try to locate its ship on the optical arrays. It would be very far away now, but if its engines were still running I could search for the Astrophage frequency, which would distinguish it from the stars around it.

There wasn't really time for this. If I was going to recover any of the contaminated fuel I needed to get to work immediately. I made my way to the control room anyway. I needed to know that Grace was okay.

Please, I thought, please please please let Grace be okay.

***

There was only an hour or two left before my next sleep when I finished setting up the Taumoeba killing apparatus. Outwardly it appeared to be many long, thick cables connecting the least affected fuel tank to one of the two I had emptied previously. But the cable was actually full of tiny, tiny little tubes that the fuel would pass through from the full tank to the currently empty one.

The cables were made of metal and had already reached the temperatures of my environment, but I was also applying direct heat to them. Astrophage would absorb heat as they passed through, and I didn't want them to absorb so much that it would cool the metal down and protect the Taumoeba. I had also filled the currently empty tank with nitrogen, in the hope that it would help kill of any survivors as they entered.

It had been a tremendous amount of work, and I wasn't sure that it had been worth it. If even a single Taumoeba survived the process it would all have been for nothing. But I had to be doing something. I had to hope there was some way I could recover extra fuel.

I hadn't found Grace's ship with the optical arrays. I spent a long time, much longer that I could realistically spare, searching for any sign of it. With the readouts set to display Astrophage frequency it should have stood out as an unusually bright spot in the sky, even at the distance it should currently be at. But there had been nothing. No matter how I expanded the search zone I couldn't find the light from its engines.

It didn't necessarily mean that it wasn't there, I told myself. I thought I knew Grace's approximate position, but I didn't really understand the "relativity" maths that Grace had done. Maybe I was just looking in completely the wrong place. Or maybe it had turned off the engines for some other reason. If it had finished refuelling the beetles, maybe it had shut them down to do an EVA and put them back where it had retrieved them from. I might have just caught in in the middle of that. I tried really, really hard to believe that might be the problem.

But what if it wasn't? If Grace was stuck out there... two tanks of fuel was enough to get me home very slowly. But it wasn't enough for me to go searching through millions of kilometres of space for the Hail Mary. And it wasn't nearly enough for me to refuel Grace's ship.

I began the transfer of fuel from the infected tank to the empty one. The infected tank was reading at 74% of optimum temperature. I had made a lot of cables to try and speed the process, but it would still take a very long time to transfer the fuel this way. By the time this tank was done the Taumoeba would have spread much further through the others. And I wasn't even sure it would help this tank.

Slowly, slowly, the fuel began to drip into the new tank. There must be something else I could do, I thought. I was using heat and nitrogen already to kill the Taumoeba, but what about the CO₂? I'd written it off making a vacuum earlier, but I was a lot more desperate now. It wasn't the vacuum specifically, it was the lack of carbon dioxide that killed the Taumoeba. Grace's ship had a system for capturing carbon dioxide and recycling it back into oxygen, could I implement something similar?

That was a long shot, not least of all because I had no idea how that system worked. But if I had any short shots to take I would be doing that. For now, the long shots were all I had. Maybe there was information about it on the thinking machine I could use.

I headed back to the workshop, very aware that I didn't have a lot of time before my next sleep cycle. What I wouldn't have given for Grace's ability to stay awake just a little longer. I might be able to squeeze in a little bit of research before I had to sleep though.

The laptop was sitting in its life support system on the floor in the workroom, right by my sleeping loops. I grabbed onto the loops with three of my arms, and used the last two to turn the laptop on and begin typing. This probably wouldn't be a good place to fall asleep anymore, since a lot of the Astrophage that had been keeping me safe had been eaten. But I could afford a few minutes to have a look through the information. I hoped that carbon dioxide was one of the few words with a very straight forward spelling, because I didn't really have time to figure out-

Grace and I had talked before about the speed of thought. While Eridians are a lot faster at maths and better at recall than Humans for the most part, we don't experience things any faster or slower than a Human does as far as I can tell. I didn't have any more time to react to what happened than Grace would have. One moment I was typing on my computer, the next my entire world had condensed down to heat and pain.

The heat didn't last long. It was gone almost as soon as it had appeared. The pain was not so considerate. Two of the arms I had been using to hold onto loops were suddenly screaming in agony. At first I couldn't even process anything else that was happening, nothing existed but the pain.

Then other things started coming into focus. My suit was burnt on the side that had been facing away from the laptop, and the arms- the arms were in bad shape. And the room was in absolute chaos. Things were flying around, colliding with each other, making an incredible amount of noise that my mind did not want to process right now.

I was confused and upset, and I wanted to understand what had happened. But before I could start trying to figure any of it out I felt a wave of exhaustion wash over me. No, no, no. The damage I had taken was triggering the sleep cycle early so that my body could work on recovery. I couldn't fall asleep in here, there were dozens of things zipping around the room and I would be exposed to the radiation for however long the cycle lasted.

Panicking, and with no idea how long I had before I was unconscious, I pushed myself away from the loops toward the door. The lab habitat had still been at optimal temperature last time I checked, if I could just make it there I would be okay. I flew out of the workshop, and down the corridor, pushing myself as fast as I could go. I clipped the wall, and my arms screamed again with fresh pain. But the lab was just ahead of me. I just needed to get to the habitat and-

Chapter Text

All things considered, I was pretty lucky to wake up again. I didn't feel lucky though, I felt awful. It was a lot like the time I had woken up in the airlock, after the catastrophe at Adrian. At least this time I didn't have a broken carapace to deal with, but my arms ached terribly.

I took a moment to take stock of things. It seemed I had made it to the lab habitat. The final moments of consciousness were a bit of a blur, but apparently I had made it in. Given how fast I was moving it was probably lucky I hadn't just hit the wall and drifted back out again.

Then I turned my focus to my arms. The surface was burnt, and the nerves were raw and pained. But I was pretty sure that them hurting was better, medically, than not being able to feel the burn. It meant that there were enough surviving nerve endings to transmit the pain. The pain was awful, but if the damage was confined to the surface than it would likely heal. That was my best guess, anyway. I still wasn't a doctor.

I lifted the two arms, and clenched the hands experimentally. That hurt even more, but the hands responded normally. Good. That was good.

But how had they gotten burnt in the first place? What the hell had happened in the workshop? I wasn't exactly in an investigative mood, but I was the engineer so it was my job. Besides, something that happened once might happen twice, and I really did not want this to happen again.

Tentatively I pushed myself out of the habitat, trying to be careful not to use the injured arms or bump them into anything. The lab clock told me I had been unconscious for over 14 hours. A little longer than a normal sleep, probably because of the damage to my arms. But the fact that I hadn't slept longer was promising. It suggested that there was no deeper issue that my body had needed to get under control.

In my rush I had left the door to the workshop open, and I could hear what was happening inside as I moved carefully down the corridor. The room was still in shambles, of course. Things weren't flying around as fast anymore, having lost a lot of their momentum to friction with the atmosphere. Now they were mostly just drifting around, occasionally colliding with each other. Some of the mess had also spilt through the open door and into space beyond. This was going to be very annoying to clean up.

First I checked on the laptop. It was fine, the life support system hadn't been damaged and it was operating as usual. So there was that, at least. It seemed like some of the machines in the room had taken superficial damage from things being flung into them. I was glad nothing like that had compromised the life support for the laptop. But what had caused the explosion? Because a sudden burst of intense heat followed by absolute calamity was an explosion. I just wasn't sure how one could have occurred on a ship with no oxygen.

As I was checking over the room, I noticed that a pipe had come loose. I suppressed a buzz of irritation. It was the pipes feeding ammonia into the atmospheric regulation system again. I had fixed those already. But that had been quite a while ago, before meeting Grace. Since then I'd had very little time for the regular systems checks that would have revealed a new issue with them. It had probably been dislodged during the explosion. At least the fail safes had engaged again. I added it to my long mental list of things that I had to deal with.

I checked the room thoroughly, but it was hard to come to any concrete conclusions with everything in such disarray. Things had moved around so much in the last 14 hours that it was impossible to say what might have happened to them just before or after the explosion. After a little while of searching I decided that I should check on the fuel tanks, and then I could come back and start cleaning up the mess.

The tank I had been attempting to filter fuel into was about 70% of the way through the process now. It had taken fourteen hours to get that far along. I dreaded to think what the condition of the rest of the fuel must be by now. But if I had managed to recover any of this fuel it would help. I pulled a samples from the filtering tank, the two clean tanks, the generator, and the lab and control room habitats, and brought them back to the temperature reading apparatus. It was in the workshop, so I had to fend off small floating objects as I set up the samples.

When they were ready I checked the filter tanks readings first. My carapase tried to sink, but there was no gravity to pull it down. 59% of the control temperature. The Astrophage population was still dropping.

I tried to tell myself that didn't necessarily mean the new tank was infected. The fuel was slowly feeding in from the contaminated tank, which was slowly losing its Astrophage population anyway. The Taumoeba might be dead by the time it got to the filtered tank, but it would still read at a lower temperature because of the Astrophage that had already been eaten. Maybe-

My whole body tensed in sheer terror as I read the temperatures of what I had thought, what I had desperately hoped, had been the clean tanks. 95% and 93% of the control temperature. The final two fuel tanks were infected. I was going to lose all of the fuel.

***

I am not a chemist. I said that before. Chemists are important to my work of course; It was people who understood the properties of elements and how they combined that created new materials that engineers could use to build. But it wasn't something I was particularly good at.

Fire can't burn without oxygen. Explosions can't happen without oxygen. But that wasn't actually right; Fire doesn't need oxygen specifically, it needs an oxidising agent. A lot of chemicals are oxidisers as it turns out, like  hydrogen peroxide,  or nitrous oxide. And sulphur dioxide. I happened to have a small cannister of that last one, which Grace had given me before we parted ways. It was part of Planet Three's atmosphere, and Grace had wanted to make sure that I had enough to replenish the farms if I needed to. It was in an cannister from its own ship, not something made from xenonite like my other chemicals.

The ammonia pipe, as it turned out, was not knocked out of place by the explosion. The screws had simply failed again, causing it to fall out of alignment. There must have been something wrong with it that I didn't catch last time, something that replacing the screws hadn't fixed. I had been so sick of the constant work, and upset about Adrian's rock being damaged, that I'd missed it. And then I'd noticed Grace's ship, and everything had gotten so busy so fast that I'd had no time to do proper maintenance checks. Grace would have been disappointed to know I'd made such an obvious mistake in my engineering.

It was almost impressive how well things had lined up to make the explosion happen. The air had dislodged the cannister of sulphur dioxide, along with several other items from the nearby wall. The cannister had struck something hard enough to release the gas inside, and then some collision must have caused a spark. I had suspected there might be some loose hydrogen from my ammonia separation, and I must have been right because it had burned . Obviously there hadn't been enough to kill me outright when it combusted, so I should probably have been thankful for that. I didn't feel thankful.

It had taken a long time to piece all of that together from the chaos left behind in the wake of the explosion. I had spent several hours researching on the laptop, searching for the relevant information and trying to understand the text-to-speak voice. The effort didn't really feel worth it in the end. What did it matter how it happened? It was all over now. None of it mattered.

Over the following 11 cycles I had tried everything I could think of, even things that made no sense at all, to try and preserve the remaining fuel. I'd tried separating it into smaller tanks, hoping some of them wouldn't contain Taumoeba, I tried heating the insides of the small tanks, I tried building a system that would bubble nitrogen through the fuel, I tried screaming at the Taumoeba and hitting the tanks with a wrench. Failure, failure, failure, failure.

The generator fuel supply was still intact, safe in its own compartment where the Taumoeba hadn't reached. Yet. And the habitats were still fully protected. But the 22 million kilograms of fuel that had been supposed to take me home was completely gone. The amount I had left would only power the drives for a few seconds.

I could try to use what remained to send a message to Erid somehow. Maybe make a very small vessel, with a tiny amount of fuel to tell them I was here and had a solution. Or I could try to build a new kind of engine that would convert the Taumoeba into fuel somehow. I didn't bother seriously thinking about either of those ideas. They were ridiculous, and stupid, and doomed to fail. Just like me, evidently.

Instead I was curled up in the lab habitat, holding the very first thing Grace had given me when we'd met all those cycles ago. I knew now that it was called a "tape measure". Not a toy, but something that Humans used to accurately measure length. Light sense was incredible, but it had interesting limits. Most Eridians don't need that kind of tool, we can hear the distances between points very accurately unless our hearing is impaired somehow.

I pulled the tab out a little way, and released it to retract back into its case. Pull, release. Pull, release. I don't know why I was doing it. It didn't make me feel any better. I could barely feel anything at all.

46 years. I had been in the Tau Ceti system for 46 years. I had been away from home for almost 50. All that time I had lived alone with all my fear, and grief, and failure. Maybe a part of me really had believed that if I just kept at it I'd find an answer someday. But mostly I had just been waiting to mess something up and die.

And then the impossible had happened. A ship had arrived from another world, with an advanced alien who agreed to work with me to find a way to save our worlds. And we had done it. We had really done it. We'd found the Taumoeba, and bred it to survive in our systems. That was supposed to be the hard part.

I squeezed the tape measure so hard I thought I might dent it. But the metal casing was sturdy, and held up against the pressure. Hadn't I done everything I was supposed to? I'd tried my best, persevered through grief and failure, risked my life, and held onto hope in the face of despair. I knew that the universe wasn't fair. You don't necessarily get things just because you worked hard and felt you deserved them. But I had overcome so much to find this answer. I had given all I had to give, and I thought I'd succeeded. Now I was supposed to bring it triumphantly home.

Why couldn't I go home.

More than anything I wished I could turn on the radio and talk to Grace. To find out if it was okay, and if it could make it home to Earth. To ask if Earth could send a mission to Erid, to save our star. To hear a friendly voice again before the end. I didn't know how much longer I would survive like this, with only a couple of small habitats to hide from radiation in. It didn't seem like a game I could keep winning for very long.

I could have gone to the control room and tried to find Grace with the optical arrays again. But I was afraid of not finding anything. It was bad enough my entire planet was going to die because of me, I couldn't bear it if Grace and all its people died too. Maybe it was for the best that I couldn't talk to it. Maybe it was better not to know for sure. At least I could hope. Grace was smart and resourceful, maybe it could prevent Taumoeba eating its fuel. It was a comforting thought.

Pull, release. Pull, release.

I wondered what Adrian was doing right then. It would still be a long time before Erid began to experience the worst effects of the Astrophage disaster. For Adrian this would be just another normal cycle, whatever normal had looked like after I left. It was probably a lot like it had been before Adrian had met me. In the end had just been a temporary deviation in its life. I hoped I had been a good one. Good enough to justify all the grief it must have felt when I never came home.

Maybe it was making art right now. Or enchanting strangers with its incredible repertoire of rock knowledge. Or meeting with its friends. Or maybe it was asleep, safe and sound with someone it loved to watch over it. I hoped it was happy. I really did. I hoped the gap I'd left in its life had been filled with something good.

I pulled out the tab again, but didn't release it this time. I held the metal end between too fingers, gently twisting it back and forth. My ship was still technically on course for the Eridani system, just not very fast. I entertained a brief fantasy of being spotted by the Astronomy Hive there, but it fell apart pretty quickly. At my current speeds it would be centuries before I arrived, even assuming the ship didn't crash into anything along the way. In many, many years I might finally arrive at the dead, frozen wasteland of Erid, and then keep going right past it because there was no way of stopping. Maybe I'd be pulled into orbit around Eridani. Thinking about that made me want to scream some more.

Distantly I heard something collide with the outside of the ship. I twitched instinctively, wanting to check the exterior for damage, but that was kind of pointless. Who cared if the ship was damaged now. Who cared if it breached and I got pulled out into space. That would proabbly be a less excruciating way to die than what I currently had waiting for me. I doubted I had collided with whatever it was that hard though. Actually I was surprised I had collided with anything this close to the edge of the system, I hadn't heard much in range of me when I'd last checked the optical arrays, Although that had been over 12 cycles ago. It was probably- 

CLANG CLANG CLANG CLANG CLANG CLANG CLAN

I started at the sound, dropping the tape measure. It spun gently, drifting slowly away, but I didn't pay it any attention. I was busy trying to focus on whatever was making that noise. It sounded like it was right outside the lab segment, but what could be making repeated strikes like that? Even if something had come loose on the ship it wasn't as though it was waving in the wind. And why-

"Rocky!" I froze. No way. There was no way, right?

".... know... hear me... on your hull..."

No fucking¹ way.

My body was in motion before I had time to think about it. I raced out of the habitat, toward the tunnels to the control room. I took a corner to hard and slammed myself against the wall in my haste. My injured arms screamed in protest but I didn't care. Maybe I had finally lost my mind. Maybe this was what that was like. The sound of the voice was so distant and difficult to hear, it didn't feel real. It couldn't possibly be real.

"Rocky!"

I scrambled desperately for the controls. The radio came on with a crackle, and over the speaker I heard the sound of Grace's voice, loud, and clear, and so undeniably there.

"Rocky!?"

"Grace??"

"Yes!" Even over the radio I could hear the joy in its voice. "Yeah, buddy! It's me!"

"You are here???" My voice was higher than I could ever remember it being. It must have sounded barely comprehensible to Grace but I couldn't have controlled it if I tried.

"Yes! I'm here!"

"You are- you-" I stammered helplessly, "You are here!"

"Yes! Set up the airlock tunnel!"

"Warning! Taumoeba-82.5 is-"

"I know, I know. It can get through xenonite. That's why I'm here, I knew you'd be in trouble."

I think I understood in that moment why Humans cry. The feeling inside me was so big it felt like it was going to tear me open. My whole body was shaking with the sheer, incomprehensible relief of it all. Grace was alive. Grace was alive, and it had come back for me. I wasn't going to die here. Erid wasn't going to die. Grace had come back.

"You save me!"

"Yes. I caught the Taumoeba infection in time. I still have fuel. Set up the tunnel, I'm taking you to Erid."

"You save me and you save Erid!" I squeaked.

"Set up the darn tunnel!"

"Get back in you ship! Unless you want to look at tunnel from outside!"

"Oh, right!"

Grace pushed itself away from the ship. I tried to bring my trembling under control, but I was too overwhelmed by the enormity of the situation. Grace was going to take me home. I was going to go home. I turned on the optical arrays hoping to hear my friend, to confirm it was really there, but the camera couldn't pick up much. There was a small pinprick of light that must have been from Grace's space suit, but it was too faint to illuminate anything properly. And we were too far away from Tau Ceti for its light to show me much of anything. I couldn't hear Grace's body at all across the void between us. But I could hear its voice over the radio, breathing hard as it climbed its tether, and complaining the whole way.

I loved that whiny Human very, very much.

***

Getting the Hail Mary lined up with my ship took a while. I still had all the pieces of the tunnel, I wanted to hold onto as many artefacts from my first contact with an alien species as possible, and the hull robot was powered by the generator so I could still use it for assembly and set up. But I couldn't move my ship at all without fuel, so Grace just had to do its very best to align its ship with mine.

The tunnel locked into place on Grace's hull, and all at once I could hear it. The whole ship, and Grace hovering inside waiting for the tunnel to pressurise. And just like that, it was real. Grace was really here. It had really travelled across the Tau Ceti system just to find me. And my whole planet was going to survive because of it.

I pressurised my side of the tunnel as soon as the seal was ready, and floated into the tunnel to wait for Grace. It was just entering its own airlock, and I wriggled and bounced impatiently. I was so full of joy I could barely contain it, I bounced between handholds as I waited for its side to pressurise. Which was a bad idea, because my arms weren't fully healed yet and the movement hurt. I bounced anyway.

Finally Grace's door opened, and it pushed itself into the tunnel to greet me. It had been over 20 cycles since we'd said goodbye forever, and it looked much the same as it had when I left it. Its face had some creases in it that I associated with it being tired. Had it not been getting enough sleep? I would have to stay on top of that if we were going to travel together again.

"I am very, very, very happy" I told it, joyfully adding it to my list of incredible understatements. My voice had come down a little from where it was before, but not by much. Grace pointed at me, at my two damaged arms.

"Are you hurt?!"

"I will heal. Attempted many things to stop Taumoeba infestation. All failed."

"I succeeded, my ship isn't made from xenonite."

"What happen?"

Grace did the loud, frustrated exhale. "The Taumoeba evolved to resist nitrogen. But it also evolved to get into xenonite to hide from nitrogen. The side effect of Taumoeba-82.5 can work its way through xenonite over time."

So it had been moving through the xenonite. I didn't realise life forms could evolve to do something like that. "Amaze." I said. I actually had very different words I wanted to use, but this didn't seem like the time to explain that kind of language to Grace. Besides, I was too happy to be properly upset right now. "Now what?"

"I still have two million kilograms of Astrophage. Bring your stuff aboard. We're going to Erid." I just barely resisted the urge to squeal. It was a shame we couldn't touch, I dearly wanted to reach out and squeeze Grace's hands in thanks and celebration. I settled for continuing my bouncing.

"Happy! Happy happy happy!" I paused. "Need to make nitrogen wash. Make sure no Taumoeba-82.5 get into Hail Mary."

"Yes. I have full faith in your abilities. Make a steriliser."

I kept shifting around. My arms were really starting to hurt. "What about Earth?"

"I sent the beetles with the mini-farms. Taumoeba-82.5 can't get through Eridian steel."

"Good good. I make sure my people take good care of you." I promised. "They will make Astrophage maybe for you to go home!" Technically I didn't have the authority to make that kind of promise, but I couldn't imagine anyone would refuse to help Grace after it had saved our people. And if they tried I was going to make life very difficult for them.

Grace's smile faded. Now its face was making a complicated shape with lots of folds. I didn't like that face shape. It was the shape Grace made when it knew something that I wasn't going to like hearing.

"Yeah... About that... I'm not going home. The beetles will save Earth. But I won't ever see it again."

I stopped bouncing abruptly. "Why?"

"I don't have enough food. After I take you to Erid, I will die."

The joy dropped away so fast it left me feeling dizzy. My carapace felt heavy as lead. The food. Grace had been worrying and complaining about the food for cycles before we parted. How had I forgotten about it? "You... you no can die." My voice had dropped down from a squeak into low tones. "I no let you die. We send you home. Erid will be grateful. You save everyone. We do everything to save you."

"There's nothing you can do." Grace said gently. "There's no food. I have enough to last until we get to Erid, and then a few months more. Even if your government gave me the Astrophage to go home, I wouldn't survive the trip."

"Eat Erid food. We evolve from same life. We use same proteins. Same chemicals. Same sugars. Must work!"

"No, I can't eat your food, remember?" I remembered. I had been so annoyed with it for experimenting with my food. It had seemed like a such waste of time then. Now it was the most important thing in the universe.

"You say is bad for you. We find out."

Grace raised its hannds. "It's not just bad for me. It will kill me. Your whole ecology uses heavy metals all over the place. Most of them are toxic to me. I'd die immediately."

I was shaking again, my whole body trembling. "No. You no can die. You are friend."

Grace floated closer to the divider wall. Its voice was so gentle, and calm. It was giving up its life to correct my mistake, but it wasn't angry. It wasn't resentful. Instead it was trying to comfort me. "It's okay." It said, "I made my decision. This is the only way to save both of our worlds."

I scrambled back from the partition. I didn't want Grace's comfort, I wanted it to survive. I remembered how overjoyed it had been when I offered it fuel to go home. I remembered its quiet confession to me all those cycles ago. It hadn't wanted to be here. It had wanted to live so badly. I couldn't let it give that up while it smiled softly and tried to make me feel better about killing it. "Then you go home." I told it. "Go home now. I wait here, Erid maybe send another ship someday."

"That's ridiculous. Do you really want to rise the survival of your entire species on that guess?" I wanted to scream. It wasn't fair. It wasn't. I would die in a heartbeat for Grace, I almost had already. I would move mountains, part oceans, invent machines to rearrange the cosmos if it meant Grace could live. I would give almost anything.

Why did the universe have to ask me for the one thing that I couldn't.

"No." I admitted quietly. Because of course, of course. Of course I couldn't trade the lives of billions of Eridians, of the entire future of Erid, for one person that I loved. The Humans hadn't been able to do it, even when it meant sending Grace against its will. Was I better because Grace was making the decision itself? I wasn't sure. Dying for the greater good simply seemed to be Grace's alignment. My emotions were so knotted up inside me that I almost laughed at that thought. Maybe this was what going insane felt like. Maybe it was feeling the urge to laugh when you were about to murder a friend.

Distantly I was aware that Grace was talking but I couldn't hear any of it. Reality felt insubstantial around me, Like I was listening to it on a screen instead of standing in the middle of it. Why couldn't I have built the Taumoeba farms out of something else. Anything else. Even if I'd used inferior Earth metals the Taumoeba wouldn't have been able to-

Wait. The Taumoeba.

Could that work?

"Wait." I interrupted, cutting off whatever Grace was saying. I wasn't a biologist, and I only had the most basic understanding of Human biology. But I thought I had found a tiny little piece of hope, and I was clinging to it desperately. "You no can eat Erid life. You no have Earth life you can eat. What about Adrian life?"

"Astrophage? I can't eat that! It's ninety-six degrees all the time! It would burn me alive. Plus, I doubt my digestive enzymes would even work on its weird cell membrane."

"Not Astrophage. Taumoeba. Eat Taumoeba."

"I can't eat-" Grace started, then cut itself off. "I... what?" The tiny bit of hope grew into something more substantial. Grace hadn't thought of this already, which meant it hadn't ruled it out already. Its face creased as it gave it some real thought, turning the possibility over in its mind.

"I...I don't know. Maybe I can."

I pointed back towards my ship. "I have twenty-two million Kilograms of Taumoeba in fuel bays. How much do you want?"

Grace's face stretched. I recognised this expression, from the first time it had told me it was going to die. When I had offered it fuel from my ship, and it had begun believing it might survive. I wanted to collapse. Maybe I had, and I just couldn't tell without gravity. Everything still felt kind of distant and unreal to me.

Could this actually work? I had no idea. Taumoeba might be distantly related to Grace, and it might be able to get usable nutrients from digesting it. But I didn't know. I didn't even know if it was likely. It sounded incredibly improbable, if I was being honesty. It still seemed like the most likely outcome of all of this was Grace dying.

But a few hours ago, I had believed that I was going to drift uselessly through space forever. Anything else had seemed impossible. Before that, I had believed that I would I would never wake again after freeing Grace from the crushing weight of its chair. Less than 72 cycles ago, I thought that I would die in orbit around Tau Ceti, having failed to ever find a way to save Erid. Grace and I had done a lot of impossible things together. We had defied every expectation, and every probability, because we'd dared to hope in the face of certain defeat. If I had to put my faith in something, I would put it in that.

"Settled." I said firmly. And then, because I wanted Grace to smile again, I pressed my fist against the dividing wall and said very certainly: "Fist my bump."

Grace laughed, and it was a wonderful sound to hear. "Fist-bump." It said, matching the gesture, "It's just 'fist-bump'."

"Understand."

Chapter Text

Sometimes I still forget.

It doesn't happen often anymore. In the beginning I couldn't sleep without waking up in a panic. It's been slow, and difficult, but in time I've learnt to remember normal. To expect the taste of natural air, not filtered through a life support system. To be prepared for the weight of Erid's gravity pulling down on me. To recognise the soft sound of Adrian humming as I come back to consciousness.

But still. Every once in a while, just for a moment, I wake up expecting to be somewhere else.

Adrian seems to know when this happens. Every time, it puts down whatever it was working on while I slept and scuttles over, settling down on the nest beside me and taking one of my hands in its own.

"Welcome home, love." It says quietly. And I squeeze its had tightly as I remember how to exist in my own carapace.

So, I saved the world. Or, it would be more accurate to say that I helped Grace save the world. Sometimes even that feels like it's giving me too much credit. There are cycles where I believe in my core that all I really did was survive long enough to have Grace save the world for me.

But hearing the sound of people walking past me as I made my way around, catching snippets of conversations and trilling laughter, the squeaking of children who will never have to know the kind of terror that briefly visited our world, I think that maybe that's enough. It's enough to have survived.

On the day that it finally ended I was impatiently waiting for my friend to finish its morning routine and come to meet me. It was running late, which wasn't unusual for Grace, but it was particularly annoying then of all times.

It had been sixteen years since we had arrived on Erid. To say that our arrival caused something of a stir would be an understatement. Almost seventy years after our ship had disappeared, an entirely different ship from another world arrived with an intelligent alien and the sole remaining survivor of the original mission. It had been unexpected, to say the least.

Everything had been very complicated and chaotic. Explaining what had happened, explaining about the predator that we had found, deploying the Taumoeba on Planet Three, co-ordinating care for Grace, and trying to get back down to the planet when the Hail Mary had not been designed to enter the atmosphere. They'd had to send a completely different craft up to collect us in the end .

When I finally got to ride the space elevator back down to Erid, there had been people waiting at the bottom for me. My parents were there, and my mentor, and my friends from the engineering hive. And Adrian. Wonderful, smart, patient Adrian, who had waited all that time for me to come home. I might have gotten a little emotional. I might have been very, very emotional. At least I hadn't had to suffer the indignity of leaking like a Human.

I kept my promise to Grace; Our people did everything to keep it alive. Scientists from all over the planet assembled to thrum solutions to its life support needs. It was larger than almost any other science thrum in our planet's history, save for when we had discovered Astrophage on our star.

It hadn't been easy. Grace was an alien being living on a foreign planet, surviving off of a life form from a third planet. We managed to breed enough Taumoeba to provide sufficient calories, but meeting its nutritional needs had been much more complicated. For a long time it had been severely malnourished. It had been so sick that for a while I hadn't been sure it was going to make it. I'd spent as much time with it as I could in those days, watching over it as it fought to survive.

But I had placed my faith well. In time, the biology hive had perfected the process of manufacturing its nutrients, and Grace had recovered. Now it lived in a large dome in the middle of our largest science centre. Thirty Eridians work maintaining its environment, and meeting its day to day needs. I've been consulted on this a lot over the years, because even after sixteen years people still think of me as the default "Human expert", despite the fact that much smarter scientists have spent that time learning much more about its biology than me.

Readjusting to life on Erid had come with its own challenges I had met with the families of every member of the original mission. Talking about their deaths had been hard. But sharing that grief with other people who had known them had been surprisingly healing. If any of them had felt cheated that I had been the one to come back they were gracious enough not to let on  to me. For the most part they seemed thankful to get to hear about their final thoughts, and about the work we had done together.

Technology had indeed taken some interesting leaps forward in my absense, now that energy was effectively a non-issue. And those advancements increased exponentially once I introduced thinking machines and Human scientific knowledge into the equation. Of course we couldn't just put Human technology into our own machines, a lot of Human technnology wasn't built to survive in our environment. We've had to figure out a lot of our own processes for manufacturing Erid-safe components. But the information from the laptop had given us a tremendous headstart on the science behind it.

It was good. Being alive was good. But there had been something looming over us since Grace had made the decision to rescue me. A question neither of us had been able to escape, until that very day.

I was waiting in a meeting room at the edge of Grace's dome habitat. There were several of these rooms, where Grace could physically meet with other Eridians. None of us would ever be able to truly share an environment with Grace, but at least we had the benefit of physical proximity. Occasionally I would use a bubble to enter the dome, and spend some time with Grace in its home. Sometimes Grace would use a special vehicle we had designed to travel around the cluster. It was a very strange arrangement, but we were making it work.

Finally I heard Grace approaching across the grounds, its cane clicking against the artificial floor. We had done a lot to accommodate Grace but there was simply nothing to be done about the gravity. It had taken a toll on Grace's joints, and now it needed the additional support of the cane to get around. It was also very slow. I should have been considerate and patient with the needs of its body, but I couldn't help wishing it would hurry up. I had news. News we had both waited a very, very long time for.

Grace hobbled into the room and took its seat across from me. "Finally!" I said, "I've been waiting for three minutes! What took you so long?"

"I'm old, give me a break. It takes me a while to get ready in the morning." It was strange to think of Grace as being old. It was only about 53 Earth years old at this point.

"Oh, you had to eat right?" I teased.

"You told me not to talk about that in polite company."

"I'm not polite company, my friend." Grace laughed. After four years together on the Hail Mary the eating barely bothered me. It was still weird, but it no longer filled me with the same sense of revulsion it once had.

"So, what's up​?" Grace asked. Of course it could tell there was something I wanted to talk about, I wasn't exactly containing my excitement. I was wriggling and fidgeting, desperate to get onto my news. Now that it had asked I didn't bother trying to dance around the topic.

"I just heard from the Astronomy Hive." I told it excitedly. "They have news!"

Grace's whole posture changed as it realised the significance of this. "Sol?" It asked, "Is it about Sol?"

"Yes!" I squeaked. "Your star has returned to full luminance!"

Grace gasped. "Are you sure? Like, 36 percent certainty?" Grace, in becoming fluent in Eridian, had taken to trying to produce some of the easier sounds of our language. Mostly the numbers. Sometimes this resulted in merging units in strange ways. But I understood what it was asking, and I wasn't about to nitpick now of all times.

"Yes. The data was analysed by a thrum of 20 Astronomers. It checks out."

Grace's breathing changed. Its body trembled. Water began welling up in its eyes. I gave it a moment to process the news. I understood what this meant for it.

When Grace had given up on going home to save me, it had also given up the chance to know for sure what had happened to its world. Earth was 16 light years away from us, so even if we could send a message to them it would take 32 years to get a response. It had sent the beetles away with the information, but it had no way to know if they arrived safely. We hadn't even known if Earth had survived long enough to receive them. For the last twenty years it had had to live with the possibility that it might never know if Humanity had survived.

But this was proof. The only way that the star could return to full luminance was if the Astrophage population had been wiped out, or reduced enough that it was no longer impeding Sol's light. The Humans had done it; They had received the beetles and released the Taumoeba population on Venus. Grace had succeeded. Earth was going to survive.

I tilted my carapace. "Hey, your face is leaking!" I teased, "I haven't seen that in a long-ass¹ time! Remind me- does that mean you're happy or sad? 'Cause it can mean either one, right?"

"I'm happy, of course!"

"Yeah, I thought so. Just checking." I held my fist up to the wall between us. "Is this a fist-bump situation?"

"This is a monumentally epic fist-bump situation." Grace said, holding its own fist to the wall.

"I guess your scientists got right on it. If you account for the time it took your beetles to get there and travel time for light to get from Sol to Erid... I think it took them less than one of your years to get it done." That was very promising. It suggested that Earth's infrastructure had been intact enough to launch a probe to Venus. I knew that was something Grace had been concerned about.

Grace nodded. I could tell it was still processing the news, and I probably should have given it some space to work through it. But within the all the joy and relief I felt there was a small, selfish knot of anxiety. I just had to ask.

"So will you go home now? Or will you stay?"

"I..." Grace began slowly, and I tried not to fidget. "I don't know. I'm getting old, and the trip is long."

"Speaking from a selfish perspective I hope you stay. But that's just me." I said, knowing that Grace wouldn't begrudge me for it. It understood what it was to me, just as I understood how important I was to it. This was what it meant to have survived together; We would always be a part of each other now.

Technically Grace could have left years ago. The Hail Mary was still in orbit around Erid, and tests were run on it regularly to ensure the thinking machines aboard still functioned. We could easily supply it with enough food and fuel for the journey back to Earth. But Grace had always been reluctant to go. It hadn't known what state Earth would be in, or if it would even have been habitable. It would be a long way to go, especially for a Human, only to discover it couldn't live there.

But now we knew. Earth had survived, and there were Humans living there in a society advanced enough to send probes into space. THe journey would be long and difficult, but there would be people waiting there for it at the end of it. It could leave whenever it wanted.

I really, really didn't want it to leave.

"Rocky..." Grace said, "that news about Sol... it... it makes my whole life have meaning, you know? I still can't... I can't..." Grace's breath caught, and it couldn't finish the thought. I didn't need to though.

"Yeah, I know. That's why I wanted to be the one to tell you."

Grace checked its wrist clock. "I have to go. I'm late. But... Rocky..."

"I know," I said gently, "I know. We'll talk more about it later. I have to get home anyway. Adrian is going to sleep soon, so I have to be there to watch." We started heading towards our respective exits, but I paused on my way out. "Hey Grace? Do you ever wonder? About other life out there?" Grace turned back to face me.

"Sure, all the time."

"I keep thinking about it." I said, walking back in a little way. "The theories are pretty hard to dispute. Some ancestor of Astrophage seeded Earth and Erid with life billions of years ago."

"Yeah, and I know where you're going with this."

"Do you?"

"Yeah." It shifted around a little. It does that when its joints are bothering it. "There are fewer than fifty stars as closer to Tau Ceti as we are. But two of them ended up with life. It means that life- at least the life Tau Ceti puts out- might be a lot more common in our galaxy than we think."

"Think we'll find more of them? Intelligent species?"

"Who knows? You and I found each other. That's something."

"Yeah. It really is something." I said. "Go do your job old man."

Grace smiled again, its face still wet. "Later, Rocky."

"Later."

I left the dome, leaving Grace behind to go to work. Grace was a brilliant scientists, and had worked with many of our scientists since arriving on Erid. But that wasn't the work it was most interested in doing when it had been healthy enough to be active again. Grace missed the job that it had left behind on Earth: teaching science to children.

From what I understood, it was quite good at it. It seemed to have a knack for connecting with curious young minds, even those of an alien species. There was some complicated selection process for what students got to attend its classes, but I didn't really care about any of that. All I knew was that the work made Grace happy, and other tutors had been impressed with its results.

I hurried along on my way home, still feeling light from the news of Earth. But there was still that pesky little knot. Grace wasn't going to leave this cycle. It probably wasn't going to leave in the next one either. But it might leave someday. And when it did, it would be too soon.

Humans are incredible things. And they are so, so short lived. Grace might only live another thirty years, assuming its health remained good. It was so little time to have with it, I didn't want to lose any of it. But did I want it to live the rest of its life without ever seeing Earth again? I had been in that position before, not knowing if I would ever return to Erid. Grace was not alone here, as I had been at Tau Ceti, but I knew it was still difficult for it sometimes.

I tried to shake the anxiety away. It wasn't a problem for this cycle. Or the next one. Or probably even the one after that. My problem right now was getting home before Adrian had to sleep.

"I'm home!" I called, as soon as I was inside. It would have heard me approaching already, but I never got tired of being able to say that. I'm home. What an incredible luxury.

Adrian scuttled into the room, holding a rock which it was in the middle of carving. "Hello, love." It said, coming over to take one of my hands in its. I squeezed it tightly. "Did you give Grace the news?" It asked.

"Yes. We didn't have a lot of time to talk, but it was overjoyed."

"I can imagine. It hasn't been easy for it all this time. And what about you?"

I tilted my carapace in confusion. "What about me?"

Adrian made a sound the conveyed that it loved me very much, but I was being very oblivious to something. "I mean that Grace is not the only one who has struggled with not knowing what happened to Earth, Rocky. I would need hearing worse that Grace's not to notice how much the guilt had been weighing on you all this time."

I shifted uncomfortably. "Maybe, but my feelings about it aren't important. Earth is Grace's world, it's not my place to be upset about it."

"You're feelings are important to me." Adrian said gently, squeezing my hand again. "I understand why you didn't want to add your concerns to Grace's, but you don't have to hide them from me."

Something clenched tightly in my carapace. Adrian wasn't wrong. Grace had taken a risk, entrusting Earth's fate to the beetles. If something had gone wrong with them, if they hadn't made it back, then Earth would have died. No second chances, no incredible unlikely rescues. That would be it. For twenty years I had wondered if all of Humanity would die because Grace chose to come back for me. Maybe Grace would have forgiven me if it came to it, but I wasn't sure I'd have been able to live with myself.

I squeezed Adrian's hand back. "I love you, Adrian."

"I love you too. Now come on, I need to sleep soon."

We walked together to our nest and I settled down beside Adrian, still holding its hand in mine. I took the rock it was working on, inspecting the carvings. It wasn't something from our world, but I recognised it from a picture Grace had shown me many times.

"It's a tree," I said, "From Earth."

"Yes. I thought it would make a nice gift for Grace's collection." Adrian had been absolutely delighted when Grace had started using rocks to decorate its home. Grace's idea of what was a good rock was very different to Adrian's, but Adrian didn't seem to mind. It would bring Grace armfuls of rocks to choose from, and they would talk for ages about what the qualities of the rocks Grace liked were, what all the "colours" were that we couldn't hear. Adrian had gotten quite good at identifying what would be a "good rock" for Grace.

"Grace will love it." I said confidently, running a finger delicately over the carving. Adrian took another one of my hands.

"You're worried about Grace leaving." It said. It wasn't a question.

"Yes." I admitted. I will miss it very, very much if it goes. But I know it would like to see Earth again. I would like it to see Earth again. I just don't want to lose the time I have left with it."

Adrian was quiet for a while. Then softly it said "You could go with it."

That caught me completely off guard. "What?"

"You could go to Earth, with Grace. You travelled together before. This journey wouldn't be much longer. You could probably even modify its ship, to make the journey easier. You are the world's leading expert on spaceship construction." I wriggled uncomfortably at being referred to that way. It was technically true; I had helped to build the ship for the original mission, and spent decades maintaining it. Then I'd spent an additional four years servicing Grace's ship, which had required learning a lot of new information from the laptop.

Adrian persisted. "You could take Grace to EArth, and let it live its last few years there. Then you could come home." It tilted its carapace slightly. "Would you want that?"

"I... I'm not sure." I said. I had entertained the possibility of visiting Earth before. I knew our people would eventually want to establish some kind of relationship with Earth, but that was the sort of mission would take a very long time to arrange. The political aspects of it alone would have our governing bodies tied up in knots. They probably wouldn't be happy with the idea of me jetting off to Earth with Grace. Things had gone well with Grace, but I wouldn't be anyone's first choice of an ambassador to Earth.

Besides, I wasn't sure if I was ready for space again yet. I had spent such a long, long time out there alone. I knew it would be safe this time, or relatively safe anyway, and it wouldn't be for so long. But it was still a frightening idea. Sometimes I felt like I'd never really left it behind.

Adrian must have sensed I was struggling with it, because it squeezed my hands tightly. "It's not something you have to decide right now." It said. "You can think about it. Maybe talk about it with some other people."

"Maybe." I squeezed back. "It would be nice to see a new world with Grace. But I wouldn't like to leave you again, we've already spent so much time apart."

"Our love could encompass galaxies. It would survive no matter how long or how far you go." Adrians voice was soft and full of love. It made me ache with joy. Then it stopped and thought for a moment. "Or maybe I could go with you. Exploring an alien world does sound very exciting." Its carapace lifted as a thought struck it. "I could collect Earth rocks!"

That made me trill with laughter, and Adrian joined in. Not long after that sleep came over it, and its hands loosened their grip on mine. I stayed sat there for a while, still holding it. In another hand I held the rock, examining the tree carved into it. Adrian had painstakingly carved each leaf, and all the knots and lines of the trunk. I remembered that conversation from years and years ago, when Grace had told me how it liked to sit in the shade of trees.

I imagined Grace at the base of a tall tree, under a sky so thin that the light of the star illuminated the surface of the planet. I imagined it among other Humans, able to reach and hold, and hear its own language spoken back to it. I even imagined it eating, sharing communal meals with great varieties of food.

There was another rock, mounted prominently on the wall of the room. It was the rock Adrian had carved for me before the journey to Tau Ceti. The rough surface where it had broken had been re-carved with the missing section. And on a random edge it had etched a small arrow, with a note that read jokingly: "This way to Sol!".

Space was still frightening. And I thought our decision makers would be dubious about the idea of allowing me to be Humanity's first contact with Eridians. And trying to modify Grace's ship for a more comfortable journey would be a massive undertaking. But maybe it would be worth it, to hear Grace in its natural environment. To be with it while it enjoyed an open sky, with no walls to hold it in. To stay by its side for however long it had left.

It wasn't a choice I had to make right now. Or next cycle, probably. But I felt a lot better about the one after that than I had before. Somewhere far beyond the atmopshere, Erindani shone as it had for billions of years before the Astrophage crisis. As it would for billions of years more. Around it Erid fell indefinitely, carrying with it everything that I loved. Here, in my home, Adrian slept, its body cooling beside me as it cycled into its healing phase. And I kept holding its hand as I watched over it, humming the tune of a song from a world far away.

THE END