A/N: With this I wanted to give BAMF!John a bit of backstory because I think for him to settle into Sherlock's insane life so easily, he must've had a pretty bonkers life himself. Also, I wanted to write an Asexual!Sherlock and let him just be asexual, which, I admit, was a little difficult for me.

That said, I want to acknowledge a fic that sort-of-not-really-but-kind-of inspired this, but I can't find it and don't remember what it was called. It has S. making J. lie down and pretend to be a crime scene and then having his way with him. It's kinky and superhot. This here fic is NOT. No sexytimes here, at all. But I just want to credit that other one; if anyone knows what I'm talking about please comment. ETA: "Undercurrents." That's the one.

A heat wave in London is an odd thing. It's not hot by any objective standard. John, who has survived the Afghani desert, and Sherlock, who has lived through Kuala Lumpur's relentless humidity and Riyadh's blazing sun, both know this. Either of them would have enjoyed today's temperature – 33 degrees – as a cool respite in those places.

But it's different in London. No one is prepared; no one has the right clothes, or the air-conditioning units, or the built-up ability to manage their soggy, steamed brains. The element of surprise makes London's heat intense and dramatic. It's all anyone can talk about. Sherlock would find that intolerably dull except that he, too is obsessed with the heat. It changes the city, presses it in closer, twists its familiar sounds and smells into a new creature, delightful and strange.

Best of all, crime rates rise when temperatures rise. A heat wave means a murder wave.

They've had one already, and it was a good one. The corpse was exquisite. Sherlock immediately recognized the killer as an artist, someone who took great care and pride in his work, not just to show off but for his own fulfillment. Sherlock crouched next to the body and examined every centimeter, admiring the meticulous lacerations, the delicate turns of the knife, the precision. Breathtaking attention to detail. He'd planned every slice before, obviously; it would be impossible to fit that many separate cuts into a single body without careful forethought. Sherlock could tell which of the cuts were made before the victim's death – oh, that one would have hurt a great deal, and that one would have just built on the last, and then this one was shallow enough that it would have been a relief, would have been almost nice in comparison, and then this one would have been horrific, but the killer backed off then, so he needed his victim conscious, this was not just torture for its own sake. It could have been for revenge or information, but either way there was absolutely no question that the killer enjoyed himself. Just look at all this posthumous damage. He didn't want to leave. And he was confident, cocky even, because he lingered long after the victim bled out. Femoral artery, John confirmed.

Well, you couldn't be bored with a corpse like that, could you? True, it wasn't the most scintillating case Sherlock had ever had. Once he narrowed the weapon down to three possible knives, it all fell into place too easily. The trail led to two rival gangs which, to his astonishment, the Yard knew nothing about. Really, what did those people do all day? And one of the gangs led to the killer, the artist who, it turned out, was quite renowned in his native Turkey, as he should be. Shame he didn't take as much care in evading detection as he did in the rest of his work.

That case ended yesterday. This afternoon, boredom is seeping in. Usually a good case will hold him over for a few days, but right now it's worse because with this heat he knows they are just around the corner, the new cases, his cases. Right now someone is plotting a murder. Someone is committing one. Right now new puzzles are being made just for him, being strangled and drowned and shot and smashed over the head. Someone in London is gasping a final breath at this very moment, and only the killer and Sherlock will know why. But it's so unfair, he has to wait for the body to be found and then wait for the Yarders to go gawk stupidly at it and then wait for Lestrade to admit he needs him and then wait for Lestrade to get around to texting him and then, and then, Sherlock will be there to claim what is his and Lestrade, the unsufferable bastard, will say, "Five minutes. No more."

He waits.

The windows are open, filling the flat with the sounds of Baker Street. A fan, sitting on the desk in the middle of the living room, oscillates ineffectually. It's hot.

John is sprawled out on the sofa, his shirt unbuttoned, his eyes closed. He's tired after the events of the last few days but he's not asleep. John has six distinct sleep patterns, Sherlock has observed, and this does not match any of them.

Sherlock opens the freezer and sticks his head inside. It's nice in there for a moment, so cold, so quiet, but nothing at all happens. He steps back, slams the freezer door, and spins around. "Bored," he announces.

John opens one eye and regards him. He tries to guess: How bored are we? Is this "I think I'll annoy John until I make him scream at me" bored or is it "perhaps I'll try to hack into Mycroft's server again" bored or is it "a bit of arson and target practice" bored? John sighs, he's just exhausted, he does not have the energy for this game. "Where's my gun?" he asks.

"Sofa," Sherlock replies, standing in the kitchen doorway and gesturing at John's feet.

"Why –? Oh, nevermind." John sits up just enough to feel under the cushion where, sure enough, he finds the gun. He fishes it out, empties the chamber, puts the bullets in his pocket, and places the Browning on the coffee table. "I'd appreciate it if you'd not keep loaded firearms under our arses, Sherlock."

"Yes, fine. John, I'm bored."

John lies back down and closes his eyes again. "Entertain yourself, Sherlock. Study something. Read a book."

"I've read them all."

"Have you read every bloody book on the internet?"

"Close. Anyway that's boring."

"Well, what do you expect me to do about it?"

Sherlock narrows his eyes. That's the thing, isn't it? John is good company and a great help but he doesn't provide much entertainment. No better than the skull as far as that's concerned. No, he's got a little more intrigue than the skull. Sherlock regards John carefully. With his shirt hanging open, a bit of the scar on his left shoulder is revealed. There's something else on his chest, and possibly something on his stomach? Interesting.

Sherlock starts to walk across the living room to get a better look, but pauses halfway there. Probably this is one of those things that is a bit not good. John opens one eye again and sees the worried frown on Sherlock's face. "What?" he asks suspiciously.

"I want…" Sherlock fidgets, his hands in his pockets. "Let me read you," he says.

"What?"

"Your body."

John's tenses from head to toe and begins to turn red, the flush starting at his chest and creeping up his neck, up his face.

"No, not like that, you idiot. I just want to look. You have scars, scars are interesting, I'm bored. Let me read you."

John is staring at him very strangely, his face an unlikely mixture of bemusement and horror.

"Please," Sherlock adds, and it sounds odd.

"Alright," John sighs. "The things I let you get away with…"

"Take off your shirt."

"Christ, Sherlock?"

"I want to see your shoulder."

"Fine."

Sherlock kneels next to the sofa and leans over John's bare left shoulder. He's seen glimpses of it here and there but he's never been able to look at it closely. Never been able to look at any living person's scar closely, actually. It's different, isn't it, when the tissue is warm and soft. The coloration is completely different, of course.

"The bullet entered here," he says, touching a point on the side of John's shoulder , "and exited here." He touches the front.

John licks his lips a little nervously. "Yeah, that's right."

"You were crouching. The shooter was off to the side of you. He surprised you. You're a good shot, very fast, you must've been distracted. You were bent over someone else, another soldier. Tending to his wounds or shielding him with your body?"

John clears his throat. "The latter."

"Mm. Yes, that's like you. It took a long time to heal," he muses. "Why so long?"

"Oh, we… Others were hurt worse than me."

"You neglected your wound trying to treat other soldiers first – with one good arm – and made your own wound much worse in the process. Very stupid. Very like you."

"Yes," John sighs. Then he adds, "She died. The other soldier. Her name was Catherine Foster. I didn't really know her. She beat me in poker once. From Liverpool."

Sherlock says nothing; as this data is irrelevant, he barely registers it. Then he remembers, people say "I'm sorry" when hearing about a death that has emotionally affected another person. Which makes absolutely no sense, because there is no possible theory by which Sherlock could be responsible for, and therefore regret, the death of Catherine Foster or John's feelings about it. Still, it doesn't cost him anything to say it.

"I'm sorry."

John knows Sherlock is just mimicking, but he smiles and says, "Thanks."

Sherlock is running his fingers back and forth across the scar and John almost shudders, but reins it in. This is not a caress, he tells himself, Sherlock Holmes is absolutely not caressing your body, he is just studying scars. And to convince himself, he looks at Sherlock's face and sees, yes, the very expression of concentration that is generally trained on petri dishes, test tubes, and corpses. His eyes are so intense they're a little frightening, and that's a relief, because it's exactly how they should look. John relaxes and looks back at the ceiling.

Having catalogued as much data as he can about the texture, color and pattern of the gunshot scar, Sherlock decides to move on.

"This one," he says, picking up John's left arm no differently than he would lift the arm of a cadaver at Bart's. He points to a small scar on John's elbow.

"Oh, that? I'm surprised you even saw that," John chuckles.

"Of course I saw it, the first time I ever saw you in short sleeves, I'm not blind." Sherlock snaps. He holds the elbow in mid air, very close to his face. "It's old. It was a pretty serious abrasion. Several layers of skin. How does that happen? Knocked down on the sidewalk. Fist fight."

"Yeah, that's it. I was, hm, 17. Jimmy Kincaid. Oi, he was a bastard. Broke my arm too."

"Yes… of course." Sherlock runs his fingers down the length of the arm and again, John wills himself not to shiver. Sherlock presses midway down the ulna. "Here."

"Christ, you're good. You can't possibly feel the old break."

"No, of course not. I deduced where it would break based on your impact."

"Well, you're right."

"I know." Sherlock smirks. "Here," he says, touching a small pock mark on John's chest. "Right pectoral. Very old scar. You were a child. Stabbed with something very small and sharp." He frowns. "Someone stabbed you?" John realizes with surprise that Sherlock is upset.

"Harry," he laughs. "In the kitchen, with a pencil. I stabbed her with a scissors, so she has a scar to match on her leg."

"Ah," Sherlock relaxes, relieved. "Cat scratches," he says in a bored tone, examining John's right arm. "One week old."

"Can you still see those? I thought they were gone. Harry's new kitten doesn't like me."

Sherlock is holding John's hand. On his knees next to John, it seems oddly tender. John almost asks Are you going to propose? but thinks better of it. "This hand was broken. The fourth and fifth finger never healed properly. Another fistfight. More recent than the other."

"Mm. About… fifteen years ago, I'd say. Broke the bloke's jaw, though."

"You usually hit with your left."

"Yeah, but my left was busy holding the other guy against the wall."

Sherlock smiles. This is the John Watson he can't get enough of, the one that surprises him. "Why? Was it over a woman?" Please say no, that would be so boring…

"Uh, sort of, not exactly. So, the first gentleman made some very rude remarks about my friend, who was a woman, but not my girlfriend, yeah? And that made me angry. So I hit his associate, and which motivated that gentleman's associate to join in as well."

"Why did you hit the first gentleman's associate? What did he do?"

"Well, the first gentleman had already left."

Sherlock grins. His eyes flick back to John's torso. On his right side, over his ribs, between six and seven, the faintest trace of a laceration. Sherlock touches it and John explodes in giggles. "That tickles, Sherlock!"

Sherlock ignores this. "Glass?"

"Is that still there? Same fight. Might've gone through a window at some point."

"Hm." Sherlock calculates the probable size of the laceration before it healed over, how the glass would've entered the skin, the velocity and trajectory of John's fall. "You were thrown through the window, but twisted to land on your side so you could get back up faster."

John nods and chuckles. "Well, I had to move fast, didn't I? There were two of them after all. The broken glass came in handy, though. It was a powerful deterrent once I had my foot on the third gentleman's face."

"All this over some rude remarks?"

"I was bored."

Sherlock laughs out loud. This John Watson is much more entertaining than the skull. He smiles broadly as his gaze flicks back across to John's left side. "You protect that side just slightly when you fight, but I don't see anything. Broke a rib?"

"Ah, three of them. On my left, yes. Four, five, and six."

"Another fight?"

"Number four went down in the aforementioned fight. Five and six, no."

Sherlock furrows his brow and stares at the ribs in question. "Car accident," he says.

"That's brilliant, how'd you know?"

"Statistics."

"Oh, you guessed then."

"I don't guess."

"You did guess. But you're right, bloody awful car accident, I was 26, Harry was driving, we were both right pissed and damn lucky my ribs were the worst damage."

"She still drives drunk," Sherlock says.

"How do you know?"

"You're not smiling."

His eyes travel down to John's stomach, where they fix on three small circles. "Cigarette burns," he says definitively. "But you're not the self-mutilating type. They're old. Very old." He'd already worked it out, as soon as he saw them, but he was avoiding the deduction till now. He looks up at John, hoping he's wrong, though he knows that's impossible. "Your father or mother?"

"My dad. My mum would never." John's voice is flat. "My dad, yeah. I reckon I was six or seven when he did those. There's a couple more on my back."

"What else?" Sherlock's voice is getting very low and very dark. "Anyone who would do this would not stop there."

"No," John answers in the same flat tone. "He didn't. He punched and kicked. He did other things that wouldn't interest you, that didn't leave scars."

It interests me, Sherlock wants to say. It happened to you, it interests me. But John would take it the wrong way, so instead he asks, "Why?" And he knows it's a stupid question, he's learned that there are an alarming number of questions that don't have answers, he hates that it's true, and he knows this is one of them.

"He hurt us to punish Mum," John replies, and his voice trembles just the slightest bit.

John hates that tremor. He's not ashamed of fear, in Afghanistan he came to know fear intimately and make it his friend, but he hates that a bully he hasn't seen in almost three decades still has power over him, even for a second. Give the bastard just one second, and John can be back there, that fast, pinned down by an enormous forearm, Mum and Harry screaming and screaming, "I Don't Like Mondays" on the radio, the smell of whiskey and floor wax and Benson & Hedges and burning. He pulls himself out of the memory and looks over to see if Sherlock noticed – of course he noticed – and finds his face twisted and his eyes blazing.

"Can I kill him," Sherlock says, and it's more of a declaration than a question.

Oh god, he probably would do it, John thinks, and simultaneously, it's so sweet that he asked permission. "No, you can't, he's dead," he replies. "Pancreatic cancer, slow and humiliating and horribly painful." He has no idea if that part is true; he knows only the date and cause of death, 20 years after he last heard from the man, but he hopes the "slow and painful" bit will make Sherlock feel better. He watches Sherlock struggling to put his face back together.

"I'm sorry," Sherlock says finally, because he knows it's what people say. John just nods.

"What was your dad like?" he asks. Sherlock's face shuts down, which is approximately what John expected. But to his surprise, Sherlock answers.

"Like us. Or rather, we are like him." John tries to imagine either Sherlock or Mycroft as a father and gets nothing. "He traveled a great deal, we didn't see much of him. And when he was around, he didn't pay us any mind. We bored him."

"I'm sorry," John says, "that must have hurt."

"No." Sherlock's face is genuinely puzzled. "Why would it? He didn't hurt us, he only hurt her." Why am I calling this data up? Sherlock wonders. It's all irrelevant now. But it seems to be relevant to John, so there it is. "She was very quiet, he saw to that, we weren't supposed to know. But we saw everything. I saw everything."

I'm sure you did, John thinks, imagining the strange, pale child skulking around the Holmes estate, discovering hiding places in every room, unraveling every secret, especially the ones that no child should ever know.

"He wasn't punishing her," Sherlock adds. "He did it because he could."

"I'm surprised you didn't kill him," John says without thinking.

"Oh," Sherlock frowns, "I tried. Mycroft wouldn't let me." His voice is tinged with regret and a bit of petulance, and John suddenly imagines the Holmes brothers (gangly teenage Mycroft, little Sherlock in short pants) huddled in their kitchen, bickering fiercely in harsh whispers over a piping hot cuppa poisoned tea. He smiles.

This is confusing. Sherlock is absolutely certain that trying to murder people, especially family members even if they deserve it, is not good. It's ok to joke about it, but surely John knows him better than to think he's joking? "What are you grinning about?" he snaps.

"Because…" John isn't sure how to explain this. "Because you are what you are and I'm your friend."

"Oh." That's alright then. Even if it is illogical and annoying.

"You can keep reading if you want."

"I do." Since he's already looking at John's face, Sherlock decides to start by examining something at his hairline. He reaches into his pocket for his magnifying glass – oh, bloody wonderful, John thinks. Sherlock's face is close, very close, as he looks at something under the hair at John's left temple.

"You're breathing," he says, irritated.

"Um, yes. Living people tend to do that."

"It's distracting."

"Sorry. Not going to stop though."

"Well, could you at least do a little less?"

John sighs and rolls his eyes. Yes, sure, breathe a little less, for Sherlock, why not. And he concentrates on making his breathing as small and unobtrusive as possible.

"There's a scar here."

"Is there? I don't think I know about that one."

"Very small indentation. Older than any of the others. Your head hit something hard when you were quite small. Must have cracked your skull."

"Oh." John swallows, doesn't know what to say. "Don't know anything about it."

"And this one on the bottom of your chin? Another very small indentation, barely perceptible, whitish."

"Oh yeah, I'd forgot about that one. Haven't noticed it since I was a kid."

"You don't know about that one either?"

"No, don't know a thing."

Sherlock returns to examining both scars with his magnifying glass, alternating between them, pressing the skin around them with his fingertips. "You were probably a baby. These could have been the regular bumps and falls of a toddler, or they could have been him. Was it him? Would Harry know?"

John pulls away, as much as he can in his position on the sofa. "What, d'you want me to ring her up and ask her? She's only a year older than me anyway, she won't know. And to tell the truth, I don't think I want to know, so leave off."

Sherlock huffs in irritation. Don't want to know? How can anyone not want to know relevant data? What could be more relevant than this? How can John choose ignorance, is he really that stupid? How can I look at his face everyday and know these scars are there and not be able to deduce who or what made them? Unreasonable. Intolerable.

John shakes his head at the anger and disappointment on Sherlock's face. "Listen. I have his ears. The shape of my ears, they're exactly like his, but that's it. Everything else on my face is my mum and my granddad. When I look in the mirror, I never see Jack Watson. I'd like to keep it that way. Ok?"

Sherlock looks away. "Ok."

"Thank you. And if by some bizarre Sherlockian method you deduce the answer, just keep it to yourself. Alright?"

"Alright."

"Ok." John settles back into the sofa.

Sherlock fidgets uncomfortably. "I'd like to… keep reading?"

John sighs. "Go on then."

Sherlock returns to his study of John's body, this time with the magnifying glass. He spends a long time on his neck, observing the color and texture left by the Afghan sun, watching the flutter of his pulse. Eventually, he continues down, along the collarbone, onto the chest.

John thinks maybe he should be bothered by this, at least a bit, but it's actually fine. The sounds of Baker Street are all washing together in a hazy muddle, with the whirr of the fan floating on top. It's hot and he's sweaty, but he has nothing to do except lie still under Sherlock's magnifying glass. I'm just Sherlock's latest cadaver, he thinks sleepily. A warm, very fresh cadaver. Nothing wrong with that. His eyelids drop and he begins to doze.

John wakes from his half sleep with a start. No one touches cadavers like that. "What are you doing?" he asks, staring at the hand spread out across his chest, over his heart.

"It's not what you think," Sherlock replies quickly, withdrawing his hand. "I don't want you, I'm not hitting on you, it's not that." He narrows his eyes and stares John down.

"Ok…" John lies back down. "Ok, I'm not angry, you just startled me."

"I'm not attracted to you," Sherlock says insistently.

"Ok, I believe you. Starting to hurt my feelings a bit, but I believe you."

"Don't be like that. I'm not attracted to anyone."

"I was joking, Sherlock. What, really, not to anyone?"

"Not to anyone." Sherlock sits up straight and squares his shoulders, waiting for "Oh, you can't really mean that" or "You just haven't met the right person yet" or "Have you tried tantric yoga?" or whatever bollocks is sure to come. A litany of insults concerning John's choice of sexual partners and suitability as a sexual partner himself is already queued up and ready to launch.

"Hm. You never feel that way at all?"

Sherlock thinks of Victor, crying and yelling, "Don't you feel anything at all?" Stupid question, why did Victor ask such stupid questions with no answers? He didn't want Victor to cry. Victor made him laugh, made him calm, made him not-quite-so-alone. So he tried to do the things Victor wanted but somehow he mucked it all up, he'd tried his best but it wasn't good enough, far from it, it was all wrong. And Victor was weak, was ordinary, had no right to stand there and tell Sherlock how wrong he was, and he would not stop and Sherlock knew a hundred different ways to stop him but they were all terrible, he didn't know any ways that were good, so he threw his fist through the wall next to Victor's head and then Victor was sobbing "I can't deal with you anymore" and he was gone.

"No," he says, in a low icy voice, glaring down at John. He wonders if he should just throw a preemptive insult to get this started.

"Hey." That's odd. John's voice sounds… normal. A little concerned, which is also odd. But mostly normal. "Hey, Sherlock. It's fine. Really."

Sherlock stares at him. John's face looks normal too. Not angry, not pitying, not confused, just John.

John gives a tiny nod, pointing his chin in the direction of his heart. Then he tips his head back against the cushion and closes his eyes. Just like that.

Sherlock places his hand, gently, on John's chest, long fingers spread out like coral.

John's eyelids flutter, then his breath deepens as he slowly sinks into sleep pattern number four.

Sherlock stays kneeling next to the sofa with John's heart beating under his palm. He's not sure what data he's collecting, or for what purpose. He's found that sometimes you can't say exactly why you're storing certain facts, but then one day there you are, you know the year the Van Buren supernova appeared, and it's just exactly the thing. Dull facts, things that any common person will know, like the name of the prime minister or, apparently, which planetary bodies orbit which – those can be safely deleted. Anyone can supply those. But specialized data can't be trusted to the world at large, it should be properly saved in case it's needed later on. He thinks the beat of John Watson's heart might be that sort of information.

He stays there until his feet fall asleep. Then he stands, stretches, walks slowly to the open window, and tucks his violin under his chin. The air is warm and damp and still and the sun is beginning to set, glowing orange across the rooftops, as Prokofiev flows out across Baker Street.