Chapter Text
Sherlock fingered the key in his pocket nervously. The key to Mycroft's house that he received years prior and never used. That night, however, he retrieved it from the desk drawer and shoved into his coat pocket on his way out of the flat. What pushed him to such extremes was the return of Sarah Sawyer. After the adventurous first date with John and Sherlock and the Black Lotus, she was back. Not scared away by the danger that seemed to surround John and his weird friend, she could be the person who would permanently distract John from his obligations as Sherlock's best friend. Friends come and go, he thought watching John and Sarah walking down the stairs. But there was one person who would never abandon him, whose duty it was to look after him even though he was an adult. His brother.
It came as a surprise that Mycroft did not wait for him, didn't sense that his company was suddenly desired. He was already in bed, sleeping soundly. Sherlock stood by the bedroom door, uncertain. He still wanted attention and reassurance that he was loved, and it couldn't wait until morning. Mycroft was sprawled on his back, features softened, chest rising and falling slowly. There was enough space in the bed for Sherlock. On an impulse, he took off his coat and shoes, thinking that he would leave the rest on, but it was so warm in the bedroom. Besides, sleeping in the nude was the healthiest option.
He slid under the covers carefully enough not to disturb his brother. He lay on his side, facing Mycroft. He wouldn't admit it, but he was grateful for his older sibling. Despite all of his flaws and his extraordinary ability to nettle Sherlock without using words, Mycroft was a constant source of comfort. Always there for him, regardless of what he had done to burn the bridge between them. Sherlock was sure Mycroft would never disown him. Also, Mycroft's solitary lifestyle meant there would never be a significant other more important than his brother.
Satisfied with that thought, Sherlock turned onto his other side and closed his eyes. He was close to falling asleep when Mycroft moved, shifted closer to him. Sherlock's eyes flew open when he felt the touch of Mycroft's skin against his back. He wasn't the only person who boycotted nightwear, apparently. He stared into the darkness, eyes huge in disbelief and confusion.
'Mycroft,' he whispered. 'Mycroft, it's me, Sherlock.'
The clarification seemed necessary. Mycroft spooned him, sighing contentedly and wrapped his arm around Sherlock's chest. To his absolute surprise, Sherlock did not find the unexpected intimacy unpleasant. He made no effort to squirm away from Mycroft's warm, bulky body. After a moment of lying completely still, Sherlock leant back against Mycroft's chest. That was nice. Cosy. Comforting.
'Sherlock,' Mycroft muttered, his breath hot against the nape of Sherlock's neck. A shiver ran down his spine. A tingling sensation wasn't limited to his back.
'Yes, it's me, your brother,' Sherlock reminded desperately. But it was too late. The closeness, the hand on his chest and Mycroft's lips so close to his neck, Sherlock bit his lip as all of that resulted in a growing erection.
He was convinced such urges were a thing of the past. Like the summer when he was fifteen and Mycroft came home for a couple of days. Still chubby, still so boring and overprotective and disapproving. Sherlock could not understand why Mycroft's natural interest in his life made him flush with embarrassing warmth. The question about a girlfriend or a boyfriend was to be expected, but his almost hysterically defensive response was not. A hand on his shoulder, an affectionate smile, swimming together and seeing Mycroft almost naked, Sherlock could not stop staring, sweating and blushing. The freckles, the broad back, even the soft curve of the stomach, he wanted to look away, but he kept watching and his eyes focused on the tempting area that Mycroft kept covered. Your brother, he told himself and his misbehaving, hard prick. Brother. His usually neglected, starved for attention cock did not listen then and certainly ignored Sherlock's wishes now.
Mycroft nuzzled his neck and finally rested his forehead against his shoulder. Sherlock lay wide awake, conflicting emotions and the arousal were bound to keep him up all night.