Archive of Our Own

The digital clock on the wall blinked a tired red: 11:47 PM. The sound of the freezer fan was the only constant noise in the zoo kitchen.

Tony absently stirred a metal bowl of dog food and frozen meat chunks, his gaze fixed on the dim reflection of the lamp overhead. The lights flickered from time to time, as if the building were breathing along with him.

Stephen was on the other side of the aisle, pushing a cart loaded with tools, medicine bottles, and new cage labels. The echo of the wheels on the wet floor made him seem farther away than he actually was.

“You should ask for time off, Tony,” he muttered as he walked through the door, not looking up. “You’re starting to see things.”

Tony let out a dry laugh. “I just see my bank account getting smaller, Stephen. That’s very real.”

The comment was lighthearted, but the tension in the air was almost palpable. Something was wrong with the zoo that week—the animals were restless, the camera system was crashing at random times, and a bittersweet smell permeated the feeding aisle.

Stephen paused, watching the shadows cast on the walls for a moment. "The cameras in the north wing failed again. I tried rebooting the system, but…" he hesitated. "The monitor went static."

Tony looked up.

The silence that followed was broken only by the sound of claws scraping against the metal of a distant cage.

Stephen looked away, resuming the cart's movement. "It must just be interference."

______

The chill in the penguin pen was almost comforting. The air smelled of salt and disinfectant, and the distant sound of dripping water reminded me of the sea.

Stephen knelt beside a shallow tank, his hand steady on one of the penguins, which was breathing heavily. The thermometer trembled in his fingers, the vapor from the cold air forming a thin mist between him and the animal.

Tony, a few feet behind, held a shovel. The metallic clang echoed every time he dumped the contents into a bucket.

"You know, Doc, sometimes I think these animals are luckier than us," Tony murmured, trying to break the silence. "At least they don't have to fill out reports after their shift."

Stephen didn't respond immediately. He was focused, counting the seconds until the thermometer beeped. When the high-pitched sound filled the room, he frowned.

"Thirty-nine degrees. Again." His voice was low, almost to himself. "That doesn't make sense..."

Tony put down the shovel, wiping sweat from his forehead, even in the cold. "Serial fever? Could be an infection."

“I’ve thought about that.” Stephen stood slowly, his gaze fixed on the overhead lights that flickered at irregular intervals. “But the tests came back clean yesterday.” He turned, meeting Tony’s gaze. “And the food’s okay, right?”

Tony nodded, but hesitated before answering. “The meat was… different today. Kind of… sweet. And it smelled weird when I thawed it.”

The noise came immediately after—a dull thud, as if something had fallen into the larger tank. They both turned their heads at the same time.

The surface of the water still rippled, but there was nothing there.

— Did you see? — Tony asked.

“I saw.” Stephen took a step forward, but the water was already calm.

For a moment, the lighting system failed completely. In the pitch black, only the sound of breathing—human and nonhuman—filled the space.

________

The metal corridor of the laboratory train vibrated slightly under their footsteps. It was the only means of transportation within the zoo at that hour—a narrow line of cars that crisscrossed the empty sections, between the cold of the cages and the silence of the observation corridors.

Tony slumped down on the bench in front of the steel counter, the sound of the bucket hitting the floor filling the air. The contents shifted inside with a wet, unpleasant plop .

Stephen, already wearing gloves, placed the small test tubes in a glass holder, each containing samples of the penguins' blood. The liquid looked darker than usual, almost thick, with a sheen reminiscent of oil in dim light.

“I swear,” Tony began, fiddling with the microscope, “if that’s some kind of bioluminescent fungus, I’m asking for a raise.”

“Fungi don’t change an animal’s body temperature that way,” Stephen replied, without looking at him. 

Tony looked away from him.

Stephen's jaw tensed. "A muscle reflex, perhaps." The sentence sounded more like an attempt to convince himself.

Silence returned. Only the rhythmic sound of the train, the distant ticking of lamps, and the faint hum of the generator filled the room. Tony leaned over the microscope, adjusting the focus.

"Okay... that's weird." His voice lost its ironic tone. "The cells aren't dead, but they're not... alive either. They're moving independently."

Stephen stopped what he was doing, approaching. "What do you mean?"

Tony stepped back so he could see. Stephen pressed his face against the eyepiece and held his breath. Inside the glass, blood pulsed, as if each drop had its own beat.

For a moment, the lights in the car flickered. The microscope made an electrical noise, and something—a brief shadow—passed across the lens.

“Tony…” Stephen took a step back. “The light… did you see that?”

Tony didn't answer. He was staring at the bucket on the floor. The surface of the penguin poop—wet, inert—had moved.

_____

The monitor flashed red, casting light on Tony and Stephen's tense faces. In the penguin area, one of the animals was convulsing, its legs stiff and body arched, saliva dripping from its beak. Each spasm seemed amplified by the zoo's heavy silence.

"Shit…" Tony swallowed, quickly grabbing the tranquilizer dart gun. "Stephen, cover me while I get closer."

Stephen didn't respond immediately. His mind raced for medical explanations, but the image of the writhing penguin froze him. "Tony… be careful. He's… different." His voice was hoarse.

Tony ran down the hallway, his feet echoing on the wet floor. Each step heightened the sense of urgency, but also the fear that pressed against his chest. The animal made strange sounds, gurgling and scratching the floor with its claws, as if trying to communicate something.

As he approached, Tony raised his gun, his hands steady despite his panic. He adjusted the tranquilizer dart and aimed at the animal, which, for a moment, seemed to be staring directly at him—black, hypnotic eyes, filled with something that shouldn't be there.

“Hold on tight,” he muttered to himself, swallowing hard.

Stephen approached the opposite side, scanning the room. Every shadow seemed to move, every noise echoed through the hallway in an exaggerated way. He reached for the ward door, ready to close it if necessary, as Tony took a deep breath and fired the dart.

The penguin shuddered violently, letting out a guttural scream, and fell to the ground, motionless. For a few seconds, silence returned, heavy and suffocating.

“Are you… out of danger?” Tony asked, his voice shaking.

“I don’t know…” Stephen replied, looking at the animal with apprehension. “But this… isn’t natural.”

_____

The penguin's body lay on the ground. The sound of Stephen's tools was the only noise in the air—the clink of metal against glass, the steady hum of the generator, the slow beep of the sensors.

Tony watched the heat monitor, his gaze fixed on the patches of color that represented the animal's organs.

“That doesn’t make sense,” he murmured. “Even sedated, the heart shouldn’t…”

The line on the monitor flickered.

“He’s still beating,” Stephen finished, finishing the thought.

The penguin, even motionless, still spasmed, as if every fiber of its body was trying to react to its own blood. Stephen ran the scalpel over the thin skin, and the scent that emerged wasn't meat—it was sweet, as sweet as fermented fruit.

“That smell again…” Tony took a step back, covering his face with his sleeve. “Just like the meat from the freezer.”

Stephen placed a drop of the fresh blood under the microscope. The image that appeared made his fingers freeze in focus. "Tony… come look at this."

Tony approached.

The cells weren't dead—they multiplied, divided, and then fused together again, as if the blood had a conscience. Some seemed to form small, symmetrical structures, almost like… eyes.

“That’s impossible,” Tony whispered. “Is this… genetic engineering? A parasite?”

Stephen didn't answer. The penguin's body moved.

Slowly. A tremor, then another. The skin began to ripple beneath the scalpel. The animal's chest swelled and fell erratically, and the low sound of spreading liquid filled the air.

“Tony… back off,” Stephen said, his voice strained.

The chest cracked open. Blood splattered onto the floor. Inside, something small—pulsing and dark—moved.

Tony staggered back, grabbing the dart gun. "What the hell is that?!"

Stephen just watched, unable to move.

The thing inside the penguin seemed to be looking at them.

The animal's body moved erratically, convulsively, but what was most frightening was the sound: a low noise, almost like breathing that came neither from the animal nor from them.

“We have to leave,” Stephen said, already heading for the door.

Tony hesitated, his gaze fixed on the table, where the penguin seemed to writhe under the inspection lamp. For a moment, something dark and shiny pierced the skin, then retreated back inside.

“Go!” Stephen shouted.

Tony obeyed. He ran. The sound of clanging metal echoed as the door slid shut behind them. Stephen engaged the safety lock with a trembling hand, the display flashing BIOLOGICAL ALERT—PENGUIN WARD.

The silence returned, heavy.

The two of them were breathing heavily in the hallway, the emergency light bathing their faces in red.

Inside, something kept moving—and banging against the glass.

Tony leaned his forehead against the cold wall, trying to catch his breath. “Tell me that wasn’t what I think it was.”

Stephen ran his hand through his hair, his gaze blank. “I… I don’t know what’s real here anymore, Tony.”

The overhead lights flickered.

Once.

Two.

_______

Footsteps echoed down the metal corridor as Tony and Stephen returned to the laboratory train. The zoo seemed colder, more alive. The emergency lights flashed in sequence, as if guiding the way—or watching it.

Inside the car, the central radio crackled with a constant hiss. Tony turned the knobs impatiently, but nothing but static responded.

"Surveillance center, this is the night team from the penguin wing. We have an ongoing contamination." His voice was hoarse. "Is anyone responding?"

Silence.

Stephen watched the camera array. One by one, the screens came to life: distorted, black-and-white images, shot from fixed angles. He clicked on the view of the penguin enclosure.

The camera shook, as if something were passing very close. The penguin's body was still in the same place, but what caught my attention was the shadow in the corner. Small, dense, moving slowly.

—Tony… look at this. — Stephen adjusted the zoom.

The focus stabilized for a moment. The shadow had form. Something dark, fluid, crawling across the floor like liquid smoke. The organism seemed to hesitate, and then crawled up the metal leg of the table.

Tony stepped closer, his eyes fixed on the monitor. “This is… searching.”

In the image, the organism leaned over the penguin's body.

And he entered.

The movement was subtle, almost imperceptible—a slight distortion, a blur blending into the animal's outline.

Stephen swallowed. “He… came back.”

The penguin moved. Slowly. First a paw. Then the head. And finally, the gaze—empty, but aware.

Tony abruptly switched off the monitor. “That’s not biology. That’s not disease.

Stephen remained motionless, staring at the reflection of the blank screen. "So what is it, Tony?"

The train shook slightly, as if something was touching it from the outside.

______

The silence of the zoo.

When Tony and Stephen stepped off the train, the air was thick, heavy—as if every breath was being watched. The overhead lights flickered in alternating lines, casting shadows that moved with them.

"The headquarters is three sectors ahead," Stephen said, looking at the digital map on his tablet. The screen was flickering, full of interference. "If the security system is still active, we can restart communications from there."

Tony adjusted the flashlight on his shoulder and held the tranquilizer tightly. "'If' the system is active… I like your faith."

The corridor stretched ahead like an endless tunnel. Sounds came from all sides—breathing, scratching, something scraping against metal.

When they turned the first corner, they saw.

The cages were open. All of them.

Stephen stopped. “That couldn’t have been a system failure…”

A low sound, almost a growl, echoed from ahead.

The lights flickered, revealing silhouettes—zoo animals, but different. They moved erratically, as if something had disassembled and reassembled them without knowing how they should look. Their shadows were too long, the sound of their paws wet and uneven.

Tony took a step back, his hand firmly on his gun. “Stephen… they’re looking at us.”

The eyes—dozens of them—reflected the flashlight. None blinked. None breathed.

For a moment, no one moved.

Then, the first roar.

The sound shook the ground. Lights exploded in sparks, plunging the hallway into a pulsing red. Tony grabbed Stephen's arm and pulled him along.

— RUN!!

They ran. The sound of footsteps behind them was deafening—it sounded not just like pursuit, but hunger. The zoo, once a structure of glass and metal, now felt like a living, breathing throat with them inside.

As they turned a corner, Stephen forced open a side door. They locked themselves inside a maintenance room, breathing heavily. Outside, the sound of claws scraping against metal echoed.

Tony leaned his forehead against the wall, sweating. "If this is a dream, I want to wake up now."

Stephen watched the shadows pass under the crack in the door. “It’s more like a nightmare.”

The sound came from all sides.

The room shook with each impact against the door, the metal screaming like a wounded animal. The emergency light blinked steadily red, and the air seemed thicker, harder to breathe.

Stephen held the radio to his chest, turning the knob in the hope of hearing something beyond the hiss.

"Central… this is the mobile lab. Is anyone listening? Answer!" His voice broke on the last word.

Nothing.

Only the distant roar and the creak of metal bending.

Tony approached, panting, his gaze fixed on the shaking door.

“They won’t answer, Stephen.” His voice was almost a whisper, a cold statement. “We’re the only ones left.”

For an instant, time stood still.

They looked at each other—tired, sweaty, covered in fear. And yet, there was something human there. A glimpse of all that remained.

“If we get out of here…” Tony began, but the sentence died before it could form.

The radio crackled.

A voice echoed, almost imperceptible, distorted by static:

Stephen felt his blood run cold. “Tony…”

The lock exploded with a sharp click. Cold wind rushed into the room, along with the sound of footsteps—heavy, shuffling.

The lights flickered one last time, and the hallway behind the door lit up in red flashes.

Tony raised the tranquilizer, even though he knew it was useless. “Stay behind me, doc.”

Stephen placed a firm hand on his shoulder.

For a moment—as short as possible—they both stood still, staring at what lay beyond. And something stared back.

The radio was still active, transmitting the sound of their breathing, the echo of their footsteps, and the last scream muffled by static.

Then, silence.

The light blinked once more and went out.