When he is six, he finds a Eurasian wren with a broken wing out in the garden.
He sneaks the bird past Mycroft and dissects it carefully in his room with an X-acto knife and his mum's tweezers. He watches its little red heart beat its last tiny beat.
By the time he is seven he knows the physiology of the twenty birds most common to southern England better than any ornithologist. He names each bone while he practices violin, working his way from the wing down: phalanges metacarpal radius ulna humerus.
Just after his eighth birthday, he builds and sets a trap for the red fox that has been sneaking around the garden at night.
At midnight, the fox is in the trap. Mycroft is waiting for him.
“I should tell Mum,” Mycroft says, and he snorts. “I thought you might be happy just catching birds.”
“Did you really?”
Mycroft says nothing, and instead kicks open the cage door. The fox scurries away, its body low to the ground.
He imagines the fox's heart, how it must be pumping blood furiously, cyclically, through its body via arteries and capillaries and veins. Sherlock wants to set Mycroft's room on fire.
“Go to bed, Sherlock.”
Mycroft leaves for university, and while Mum is all tears and watery words, Sherlock delights in the idea of having the run of the house, with no older brother watching his every move. These hopes are quickly ripped apart: Mycroft visits almost every other weekend.
“Have to keep an eye on my little brother,” he says.
Sherlock screws his eyes shut and tries to cope: bed on fire wardrobe burning wallpaper charred and peeling and then nothing left.
Sherlock does not understand his classmates, the way their eyes widen and narrow when they interact with each other, the way their lips quirk and their hands flex and their fingers twitch, wanting to touch. But he becomes a mime quickly, faster than they can figure out that something is wrong with him. Very bright, his teachers say. A bit awkward, but very bright.
There are times when he falters, but he learns how to recover, how to pass it off as simple social ineptitude. He does not tell his classmates that he would prefer them quiet and placid, so he can open them up and see how they work. The biology books in the library can only do so much.
But he has gathered that these are not the things you tell someone to get them to like you. To trust you.
He is fifteen when he meets his match. Jim Moriarty is a kind of creature that Sherlock has never encountered before: he understands.
They bump shoulders in the hallway at school, and Sherlock knows that this boy does not belong: he has never seen him before, and his school uniform is obviously stolen.
“Meet me at the gates after school?” The boy's voice is low, and his fingers press against Sherlock's wrist. Sherlock nods, and spends the rest of the school day paying no attention to his teachers and committing everything he observed about the boy in the hall to memory.
“I've been watching. I know what you are,” Jim Moriarty says when Sherlock walks up to him. “I am, too.”
The wind picks up, so Sherlock puts his hands into his blazer pockets and appraises the boy in front of him. Jim Moriarty is pale with sunken eyes and has a smile that reveals absolutely nothing.
“So, let's play.”
Sherlock feels the thrill down to his toes.
The following week, the newspaper announces that a girl has gone missing a few towns over. Sherlock reads article, rings the local police, explains the case in five minutes flat (but neglects to identify the culprit), and hangs up before the officer taking his call can get a word in edgewise.
Then, Sherlock begins to plan. Call and response.
His first human is nothing short of glorious.
The human heart is a beautiful thing. It is better than wrens, better than foxes, better than the neighbour's cat. His hands are red. It will take a very long time to get them clean again.
He leaves no evidence. No one will find the body, let alone figure out when and where it disappeared.
Mycroft visits again the following weekend, and he knows, instantly, the second Sherlock raises his eyes to his brother's.
Hearts are his favorite, he decides. The other parts are nice, but just not the same. It's a pity he has to get rid of them.
The night before he leaves for university, Mycroft (home again) comes into his room and gives him a talking to.
“So help me, Sherlock, if you're not smart about this -”
“I am smart about everything,” Sherlock says flatly.
Mycroft's jaw twitches and his fingers clench and Sherlock knows that his brother would very much like to punch him in the face.
University is entirely uneventful. He is initially concerned that perhaps these new classmates will be smarter than the old ones, but he is still the smartest. Even so, he does his best to remain unremarkable, associating with unremarkable people, attending class, handing in work, and only giving in when he cannot stand it anymore. He is careful. He is always careful. Can't have Mycroft worrying about it.
London hearts are the same as the ones at home.
He begins harassing Detective Inspector Lestrade a few months before graduation, buying a mobile phone and bombarding Lestrade with solutions to the unsolved cases he reads in the newspapers until he is allowed to visit the crime scenes himself.
He cannot help but critiquing his peers' work. Four out of five London murders are committed by pathetic amateurs, but Sherlock begins to live and breathe for the exceptions to the rule.
Solving cases helps, but it is merely a distraction, not a cure.
“I have just the flatmate for you,” Stamford says, and Sherlock can only assume that the man is a terrible judge of character. “Old uni mate of mine.”
Dr. John Watson walks into the lab and Sherlock sees psychosomatic limp and just returned from military duty and brave well-meaning kind.
Donovan lifts the police tape for John to duck under, and then grabs his arm.
“You be careful, alright?” John frowns at her, and she shakes her head. “I've seen plenty like him, trust me. He doesn't care. He can't.”
“Sorry, what do you mean by -”
She catches Sherlock leaving the crime scene out of the corner of her eye, and lets John go.
“Just think about it.”
But Sherlock says the code predicts a man's murder and they are off on a whirlwind tour of London that leaves Donovan's warning on the pavement at her feet.
The case ends with a handful of men in prison, one man fleeing to America, and Sherlock muttering nothing but Jim Moriarty to himself for the next few days.
John is awake at three in the morning, real pain in his shoulder and unreal pain in his leg. He's reading one of Sherlock's books (beekeeping, of all things), determined not to use the painkillers he's been prescribed. Sherlock walks in, tosses his coat on the couch, and promptly begins stripping in the kitchen.
“Hello,” John says, and Sherlock is already shirtless and peeling off his socks. John catches stains of dark red on Sherlock's trousers before they're thrown onto the floor. “Bad night?”
“Dirty,” Sherlock replies. “Beyond cleaning.”
John returns to reading about nocturnal bees, and the next time he looks up, Sherlock's clothes are burning brightly in the sink.
About a month later:
“Where do you go, on nights like this?”
It's three thirty-four in the morning, and John has been waiting for Sherlock to return.
“Nowhere you'd find interesting.” Sherlock stares John straight in the eye.
“The morgue, then?”
“Mm,” Sherlock picks up the newspaper lying on the couch and skims it, uninterested. “Something like that, yes.”
John is whisked away by Mycroft a few days later. They meet in the standard nondescript warehouse, Mycroft wears the same boring suit.
“He likes you because you react the way people should, and obviously so. You're his translator, if you will,” Mycroft says, watching John carefully. “My brother has extremely little empathy for others, if any at all.”
John just stares, and Mycroft sighs.
“Come now, John. You can put this all together without having me spell it out for you.”
John sieves through the pieces he has: Sherlock coming home late, often. Dirty (red) clothes burning in the sink. Morgue-not-the-morgue. Donovan says: he doesn't care, he can't. Little pieces of psychology classes from uni come back: no concern for the feelings of others, disregard for social norms, inability to maintain relationships...
Whatever remains, no matter how mad -
“He was opening up birds by the time he was six. But don't worry, he's taken a shine to you. You're the safest man in all of London. Maybe even Surrey and Kent.”
John covers his face with his hands and inhales, exhales. He hates Sherlock for taking away his own impassivity, that old, long gone ability to glance up at the world around him, be it Afghanistan or London, and simply go about his business. It was all his fault, John thinks – Sherlock had made things bright and kinetic, but that didn't matter, not if Sherlock was –
“You're a good man, John Watson,” Mycroft says. “I think my brother is quite sure people like you aren't supposed to exist.”
John's entrance into the flat interrupts the violin. Sherlock gives him a once over, and then turns back to the window.
“I assume Mycroft has explained the situation to you.”
“And what if I leave?”
Sherlock freezes, fingers still on the neck of the violin, and his eyes widening with possibility.
“Oh, that could be fun, John.”
John imagines the game Sherlock would play with him, and John is sure that at the end of it, he would wake in the middle of the night to find Sherlock, eyes bright and pitiless, at the foot of his bed, no matter where he slept.
“But, if you value your own physical, mental, and emotional well-being, I think it would be best if you stayed.”
Bach's Partita in D minor for solo violin fills the spaces where silence would be for the rest of the night.
A few hours later, John dreams:
Body was a puzzle. Picked apart, piece by piece, by hands with long fingers.
He wakes up and realizes that he can never be boring, not ever again.
Danger night. You should lock your door.
John is awake when Sherlock returns at three fifteen in the morning, but pretends not to hear Sherlock's fingers running down his bedroom door before gently testing the handle.
“I know,” Molly says softly. Her eyes flicker around the room, then to John's. “I let him do the autopsies, sometimes.”
She continues to work on the corpse in front of them, frowning as she pushes aside organs.
“Um. I,” John starts, and Molly blinks at him, her gloved right hand somewhere between the dead woman's stomach and kidney. “If you ever want to get a drink sometime – I mean, even tea.”
"If you ever want to talk, John, I'd – I'd be happy to.”
“Sometimes I wish you were, John.” Sherlock's voice is low as he sinks into his chair. It's another danger night, but Sherlock is home early.
Sherlock tilts his head and watches John, expression unreadable.
“We would be a good team, I think.”
John coughs, then sits up slowly. He walks to his bedroom and shuts the door.
He has a text in the morning:
You're lucky he likes you.
Sherlock returns one night with a bloody nose, a gash on the side of his head, and a deep cut in the shape of a smile above his collarbone.
“Ran into Jim over in Whitechapel,” he says breathlessly, a flush high on his cheekbones.
“I bet you thought that was bloody romantic,” John mutters, as he heads over to the bathroom to grab the first aid kit.
“Does he have a type?” John asks Mycroft the next time they have one of their meetings.
“Male, one metre seventy-three centimetres, mid-thirties, dark eyes and hair, Irish accent. Of course, we're describing the most ideal candidate.”
John is duct taped to a kitchen chair, wrists and ankles bound tightly together, with far too much tape is covering his mouth. Jim is standing behind him, drumming his fingers on the back of the chair.
“You're home early,” Jim sing-songs, and Sherlock finds he cannot help but keep his eyes on John.
John stares intently back, shoulders moving ever so slightly, and Sherlock receives the message: buy me time.
“Get out,” Sherlock says, as his eyes dart around the room, hoping to find some obvious solution to the problem. But Jim is a wild card, impossible to predict, and Sherlock cannot calculate probability when he is involved.
“Oh,” Jim whispers. He has realized something wonderful. “Sherlock does not play well with others, hm? Never learned to share?”
Sherlock's jaw locks and his molars grind against each other. Sherlock is always cold – but he is a wasteland now, savage and raw, promising slow death.
“We could have good fun with him, you know.” Jim gives John a sympathetic smile as he runs a finger along John's jaw. “He's very nice.”
“Get out.” Sherlock's voice is flat and impassive, but Jim knows Sherlock's miniscule tells: his fingers are twitching in the direction of the pistol he keeps stored behind a loose brick in the fireplace (an amateur mistake, really). Jim shuffles over to the fireplace and throws the brick to the floor. He trains the pistol first on Sherlock – then grins and places it against the base of John's skull.
“Or how about I end all the fun right here? He's no good for you, baby. We were made for each other.”
And then there's the rip of duct tape and John is twisting, his clasped hands together and flying upwards, smashing into Jim's face. The pistol and John fall to the floor with a thump. Sherlock dives for the gun and succeeds, but Jim has already made his way to the door. The blood running over his lips and down his chin makes Sherlock's heart skip a beat.
“Told you,” Jim says, pinching the bridge of his nose. “No good for you.”
He closes the door quietly, and that is the end of things.
“You're alright,” Sherlock states as he pulls John up, and then tears the tape keeping John's wrists and ankles together violently. He pulls the strips covering John's mouth off in one swift motion, and John yelps before checking his face with his hands.
“Just peachy, thanks.”
Sherlock finds himself staring at John for far too long. He knows because John breaks eye contact and focuses on his raw wrists instead.
“No good,” Sherlock agrees, and then retreats to his violin. Nothing more is said on the matter.
Danger night lights up John's phone. He leaves his bedroom door unlocked.
Sherlock comes home at five in the morning, smelling of bleach and hand sanitizer.
“I really am, John,” Sherlock murmurs as he sits at the foot of John's bed.
“Beg pardon?” Sleep makes the world stranger and thicker than fog on a moor: John almost doesn't feel Sherlock leaning over him, almost doesn't feel his fingers trace his sternum, or splay out over his heart.
“Quite fond of you.”
There are days that John likes to imagine that his flatmate is nothing but a man who solves mysteries.
There are nights when Sherlock's eyes meet John's, and John knows that if Sherlock could, he would slice himself open and let John look.