Sherlock detests sleep. Avoids it whenever possible. It's dull, pedestrian, unproductive and a waste of time. He only sleeps when it becomes absolutely necessary. When his body and mind are on the edge of collapse from over-exertion. Sleep was never a voluntary activity for him.
At least that's how it used to be. Now he sleeps quite regularly. Even on cases.
But only in the back of a cab. This is because of a certain jumper-wearing doctor that shares the cabs with him. Because in the cabs he can pillow against the above-mentioned doctor and sleep quiet contently.
It started out by accident of course; this "pillowing arrangement." They'd been on a particularly brutal case for over a week; a string of child murders made to look like suicides. The killers knew what they were doing and were painstakingly thorough in covering their tracks. Even managed to feed them a few false leads. Not thorough enough to trump Sherlock though. It had taken 9 days and a 3 hour foot chase across London, but they finally managed to apprehend the murders; workers for a cleaning company that were hired by the parents of the children. Sherlock had barely slept the entire time and when he had it'd been brief one hour naps forced on him by a concerned John.
Needless to say he was exhausted and five minutes into their 45 minute cab ride home he fell asleep. He'd just drifted off sitting straight up at first but slowly; as the cab moved and his body thoughtlessly sought a more comfortable position he drifted towards John until he was leaning on him entirely. He wasn't even aware of this until he slowly came to; with a gentle prodding and familiar voice saying "Wake up Sherlock. We're back at the flat." He was groggy and didn't really understand anything other than the fact that he was very tired and had an unusually warm and cozy pillow.It smelled good too.
So he just burrowed closer muttering objections as he began to drift off again. John chuckled and it rumbled pleasantly through Sherlock. "No wonder people talk." he muttered, in amusement more than irritation. Still he renewed his efforts; shaking Sherlock. "Come on you big lump. Wake up or I'm going to leave you in the cab." Reluctantly Sherlock stirs and grumbles that John "Wouldn't dare." but straightens up and climbs out of the cab anyway. They make their way upstairs with Sherlock yawning the whole way and John fighting back giggles at his sleepy friend. Really there isn't anything more amusing and adorable than a sleepy Sherlock. But John would never tell him that. They get into the flat and skip their customary tea and food; instead preparing immediately for bed. He doesn't say anything about Sherlock cuddling up to him in the cab, but gives him an unusually warm and soft smile when he bids him goodnight.
Sherlock goes to his room and tries to sleep again, but it's not the same without his jumper-clad pillow. Instead he ends up nicking John's laptop and typing up details of the case for his website; only drifting off sometime in the early morning for an hour or two. He's thankful John never mentions it; because he's really not a cuddly sort and the whole thing would be a bit embarrassing to discuss.
But the experience taught him that sleep or at least rest, can in fact be pleasant and the moderate embarrassment is certainly worth it.
Now whenever he can he sleeps in the cab, or pretends to. It's a marvelous excuse to lean against John; listening to his heartbeat, steadfast and comforting as the man himself. Feeling the soft rise and fall of his chest as he takes in rhythmic, shallow breaths. Allowing John's soft, warm, familiar scent to envelop him and attach itself to his clothes, where it will cling for the rest of the night. This is why he doesn't bother to change before bed.
And John is none the wiser. He's simply thinks Sherlock has finally started giving into his body's demand for rest and is unaware of his snuggling habit.
Not that he minds of course. He actually quiet likes it; though he'll never admit it out loud. These cab rides home have quickly become his favorite part of the cases. With Sherlock's warm weight against him, his curls rustling as he breaths across them; inhaling their crisp scent.
Sometimes he'll catch the cabbie watching them; smiling. And John will smile back. They're not a couple; not likely that they ever will be, he thinks, but it's still nice to pretend. And he does. He watches Sherlock sleep, studying his angular, porcelain face in the dim lights that dance through the cab windows. He doesn't get many chances just to look at, to marvel at Sherlock; who would surely notice if John tried to sneak glances at him while he as awake. So he takes this time, this chance that's been granted to him.
He often prays for heavy traffic to lengthen their ride or perhaps road construction causing a detour. Anything will do.
He's usually careful not to move so he doesn't awaken Sherlock or dislodge him. Once Sherlock's settled against him for the ride he usually maintains that position the rest of the way; even if he's moderately uncomfortable sometimes. But tonight he's feeling particularly courageous. Maybe it was that rare warm smile Sherlock shot him when he helped to piece together the finale bit of the puzzle on the case. Maybe it's just the desire that's been building in him since these cab naps started.
Whatever it is, he abandons his usual caution and gently tilts his head to press a careful kiss on Sherlock's head. His lips brush the silken curls and he allows himself to pause; breathing in the moment. God, he's wanted to do that for so long. He wants to do more of course, but it's a start. He lets out a contented sigh and gently rests his head atop Sherlock's; thankful for over-exhaustion and the chances it presents him.
Sherlock; who of course is not asleep; snuggles closer to John at the touch. He smiles into the dark at John's tender action and contently murmurs his name. Perhaps soon enough they'll be doing this without the pretense of exhaustion and sleep. At least he hopes so. And John does to, of course.