John didn't even move when the trap door opened and Sherlock appeared in the opening, then proceeded to haul himself through and up onto the roof. He knew Sherlock would find him up here eventually; a man like him wouldn't think twice about invading someone's personal brooding time.

"You never really can see the stars in London," John says to the dark coat that drops beside him on the shingles. "Just the suggestion that there might be stars. The occasional point of light here and there, enough to make you realize what you might be missing."

"Is hiding something you do fairly regularly?" Sherlock rumbles, settling more comfortably on his elbows, head tipped back to gaze upward, the orange haze of streetlights and cars and houses tinting the dark sky and the long, smooth column of his throat.

John ignores him. "We'd take night patrols out into the Kush, hardly anyone was around, and the night would be so completely pitch dark. The only light was from the moon and the stars." The sky would be brilliant, an entire swath of glorious, sparkling light, the Milky Way cutting across like a purple ribbon. He's glad he's home, but he does miss the stars.

Comfortable silence descends, both of them relaxed, and John's glad Sherlock isn't the kind of man to make useless conversation. They simply breathe for a while, each lost in his own thoughts. John's starting to feel the cold creep through his coat and thinks it might be time to go back inside when Sherlock speaks, voice low.

"Is that when you were shot? On a night patrol in the mountains?"

John turns his head to look at Sherlock's profile. He hasn't moved; he's still looking up, as if any answer that John might give would hold no surprise for him. "No. Firefight near Jalalabad, in the Kabul River valley," he says, turning his head back to contemplate the clouds beginning to slide across the sky.

John suddenly feels fingers on the inside of his wrist, tracing their way down the base of his thumb, feeling and exploring the calluses still present from months of carrying a weapon in the thin dry air. He doesn't move despite the heat pooling low in his belly, because he's already been warned off once tonight and he's not about to make a fool of himself twice.

"You killed a man for me tonight," Sherlock says, and curls his hand around John's.

"Yes, well, don't feel too special. It's not the first time."

"But you barely know me."

John shrugs. His heart is hammering double-time, palm itching to tighten against Sherlock's soft skin, thread their fingers together more securely. He finds it hard to pretend indifference when Sherlock lifts their joined hands to his mouth and kisses John's thumb.

John exhales, a rush of sound through his nose. "You sure?"

"Do you think I'd ever do anything I wasn't sure of?"

"No. And I highly doubt you'd ever do anything that anyone told you to, either," John says, feeling a shiver run through him. Christ, it's too cold for this. Before he can suggest moving inside, Sherlock is kneeling over his body and straddling his thighs, long dark coat covering both of them.

"You're right about that," Sherlock murmurs, bending low and tracing his nose along John's cheek. "But if you told me to fuck you, I wouldn't say no."

John slides his hands up Sherlock's thighs, tilting his head to capture Sherlock's mouth in a slow, lazy kiss. It's been an unbelievable night already, what's one more insanity to add to the mix?

"What if I told you that I wanted to fuck you?" John says, reaching around to grasp Sherlock's really very fine arse and giving it a squeeze.

"Whatever gets you off," Sherlock says, and leans back to work on his belt and trousers. He strips his lower half fairly efficiently, considering their precarious footing, canting a long leg back over John's lap to start on John's trousers, opening the flies enough to pull John's erection into the cool air.

John jumps at the touch of Sherlock's hands. "Christ, your hands are freezing! Get up here, let me kiss you again." John pulls Sherlock's body against his, tucking their hips together and feeling the silky heat of Sherlock's cock sliding against his, their body heat trapped beneath Sherlock's coat. He really wants to be buried to the hilt inside Sherlock's body, feeling Sherlock come apart above him and breaking down that cool façade he's wrapped himself in. But the roof is slick, Sherlock's kneeling directly on the shingles, and they're both going to freeze to death if they don't get inside soon. So John grasps his hips harder, and begins to rock up against Sherlock's body. He waits until Sherlock takes up the rhythm before he spits into his palm and slicks their cocks where they're pushing against each other.

Sherlock's breath is coming out in soft huffs, clouds of mist clinging around his head as he grinds down. There's more to this, John thinks, than a quick frot on a rooftop; more than life-affirming sex after a wild night. Sherlock's reaction to John's honest praise gave John a glimpse of the vulnerability that Sherlock tries very hard to hide, wrapping himself in sarcasm and cold hard brilliance like armor. John sees it, though, knows Sherlock is more than he lets on. John's pretty sure Sherlock is going to save his life, if not literally then at least through the sheer audacity of his existence. Now that John's had a taste of that life, that existence, he wants it more than anything. They'll never be able to tell each other that, though, so they'll have to settle for this.

His orgasm is creeping up on him, and watching Sherlock gasp and bite his lip after a particularly sharp twist of John's palm over their cocks makes his arousal spike. "Jesus, Sherlock, you're so fucking beautiful, you know that?"

"I've been informed," Sherlock gasps, rocking harder, his balls sliding against John's. "Yes, John, with your thumb over like – augh, yes, fuck, I, I …" and suddenly Sherlock is shuddering above him, semen spilling across John's stomach, increasing the slip of their bodies against each other as John works his hands faster. He's there, God, he's there, and when Sherlock drops down to crash his mouth against John's, kissing him wildly, nipping his lips and licking into John's open mouth, he arches and comes hard, wrapping his arms around Sherlock' waist and digging his heels in to make sure they don't slide down the roof.

They look at each other in the dim orange light, Sherlock's pale eyes searching John's face, probably looking for any trace of regret or shame, and finding nothing to give him pause, smiles brightly.

"Your room is ready," Sherlock says, rolling off of John and pulling his trousers up and pushing his shoes on, picking up his socks. "You'll bring your things tomorrow? We'll have to go in and give Lestrade a statement, but I'm sure we can come up with something convincing by then."

John laughs and shakes his head. Even insanity is normality, it seems. "Go on, I'll be down in a minute."

Sherlock looks at him sharply. "Hiding again?"

"No. Since I can't see the stars, I might as well watch the dawn," John gestures to the pink and orange starting to stain the eastern sky.

"Then I'll watch with you," Sherlock says, and he tucks up against John's shoulder, watching the sun break across the sky.