Sherlock never leaves - at least, not in the way that John does. He doesn't pack a suitcase and check into a hotel; he doesn't whimsically buy a train ticket to Paris because it was half price and spend the rest of the four day trip regretting the splurge; he doesn't leave his mobile on the table in Baker Street and attempt to just get on with life in the biggest gesture of fuck you he can think of.
Instead, Sherlock is very good at ignoring John's entire existence. Sometimes Sherlock takes himself off on a case and leaves John behind to worry and stew about the empty space in the flat; sometimes he'll disappear into his room. Most often, though, he sits in the kitchen fiddling with various contraptions and chemicals and controls and is silent. He doesn't even mutter to himself under his breath like he usually does when he's experimenting.
During those fights, John spends long, lonely nights in bed staring at the ceiling and wondering why the hell he puts up with it.
He never does quite come up with an answer. Not a suitable one anyway.
But then one of them will crack (or John will return from Paris, or wherever he's taken himself off to and Sherlock will watch him for a few long minutes before huffing out an amused breath and throwing John's phone at him) and it doesn't matter that there isn't an answer to the question.
They never do quite fit back together. Not entirely. John sees the way Sherlock will be hesitant to reach out to find John's warmth on the couch; Sherlock will notice (of course) how John's eyes don't quite stray but linger on other people and once Sherlock even caught John staring at a couple sitting on the bench next to them at the train station before John had sighed resignedly and turned back to the paper in his lap.
Sherlock sees the distance between them; John feels it.
Neither is willing to acknowledge it.
Until one day, John does.
He comes home from a day of teaching at Bart's and Sherlock is lying with his feet against the wall, head and shoulders on the floor and he just knows that he can't do this anymore.
"Sherlock…" he begins and his voice is so weak, so strained and he hates it.
Sherlock tilts his head towards him then and his legs slide down the wall and he moves until he's sitting with his back against the coffee table and his knees resting against the couch, his feet planted firmly on the floor. He's not looking at John anymore and when John repeats his name Sherlock licks his lips and looks down.
"Right. Of course."
He turns towards John then and John, a year ago, wouldn't have thought it possible but there are tears in Sherlock's eyes and John feels his own start to burn.
"I'm sor-" John begins but Sherlock shakes his head and cuts him off.
And that's all he says before he returns to staring at his knees. John watches him and it hurts, damn it and Sherlock won't even look at him.
John turns to go but pauses when Sherlock says his name.
"You…" But he falters and John can't bring himself to turn around and look at his face. He just can't.
Sherlock knows that, despite the best intentions, some things just don't work out.
Still, it comes as a surprise to him when his and John's relationship falls into that category. It shouldn't. But it does.
The worst of it is, Sherlock hasn't even done anything wrong. He's wanted to – God, he's wanted to, especially when the Russian ballet had been in town and the young Irina had cornered him in the dressing room he'd been investigating and, fuck, she'd been beautiful and intelligent and almost (almost) irresistible– but he hasn't.
It's easier to watch John go than he thought it would have been.
It's five months before Sherlock sees John again. It's at Bart's and John is talking to Molly when Sherlock swoops into the lab already talking. He sees John and he wants to backtrack, wants to leave because of course, how could he forget that John and Molly have a 'friendship' now. Sherlock thrills slightly when John starts but he doesn't smile (he's not entirely sure that he can, if he's honest).
"Sherlock," John says with a nod before smiling at Molly and leaving through the side door. Sherlock watches him go and he's surprised by the tug that makes him want to follow. He thought he was over that.
He sees him again six weeks later (who knew London was just a small village, at times?) and he's having dinner with a woman who is entirely too pretty and blond for Sherlock's liking. John looks interested, though, if not exactly happy and Sherlock finds that he's quite pleased by that.
It takes Mycroft ten hours to find him. It's an eternity quicker than Sherlock wanted to be found but three hours longer than he thought it would take.
Mycroft locks him up in the Big House for the ten days it takes for the concoction of drugs to clear his system entirely.
Then he puts Sherlock through the worst tongue lashing he's had in over a decade (since the last time he'd almost OD-ed in fact) and by the end of it, Sherlock's fingers are itching to plunge another dose into his arm.
"She's not you, Sherlock-"
"Of course she's not," Sherlock murmurs and takes a step closer to John – and oh, his scent is almost intoxicating (and maybe Sherlock's a little high, still).
"But we gave it a go, Sherlock. It didn't work."
"No, it didn't," he agrees and takes another step closer and he's fascinated by the slightly glimmering plastic buttons of John's moss green cardigan (it's hideous but John still looks gorgeous, of course he does). "Maybe… we should try again," he manages as he breathes against John's neck and his scent is so much stronger there and Sherlock drags his nose up and down the thick cord of muscle there, his tongue dragging over the skin when scent alone isn't enough.
"We… shouldn't," John counters.
But they do.
The sex is great. The relationship is not so great. John doesn't move back into Baker Street and when they decide that it's not working out (again) three months later, both are glad of that fact.
It just saves a lot of hassle.
This time, John's the one who convinces Sherlock it would be a good idea to give it a go. Sherlock agrees because, since John's been gone (ten months, this time. Sighted only once in those ten months and it had been with a red head who was entirely too short and too female) Sherlock has been high as a kite and Mycroft's net has been closing in and the threat of the Big House looms large again.
It lasts five and a half weeks before Sherlock demands that he never see John again.
Mycroft decides that enough is enough and takes to do with it the way he does everything else in the world. Sherlock doesn't find out until John is already settled in Newcastle with the red head, a full time teaching job at a university up there and the red head has a ring on her finger.
Sherlock goes willingly to the Big House this time and Mycroft stares quietly at him the whole journey there.
Sherlock doesn't mind it as much this time but he stares out at the passing greenery with a glare, anyway.
He doesn't move back to London. He goes from the Big House to the Even Bigger House in France and lives with Mummy for four years until she finally succumbs to the myriad of illnesses that have plagued her since Sherlock can't remember.
He cries at her funeral and Mycroft stays in France for a month before government calls him back for the unexpected election following the collapse of the latest coalition.
Sherlock lives alone in the house by the sea for five years before he goes back to London.
He forgets, sometimes, what language he's supposed to speak. Even when Mycroft had visited in France, they'd spoken French to one another and so when he sits in the back row at Lestrade's funeral (heart attack, too much work, he'd only been forty eight) and Sally Donovan, now a Detective Inspector startles him with some quiet words he responds to her in French and she's gone before he's even realised his mistake.
He doesn't speak to anyone (not even John, who tries to corner him at the wake) until he reaches the airport in Lille and has to tell the cab driver where he's going.
His phone, when he turns it on, has seven voicemails.
He deletes them without listening.
He fires the beekeeper and takes to the job himself.
He'd not realised how much he'd missed London until he'd gone back.
The bees distract him.
Mycroft comes for Christmas and it's a quiet affair, just the two of them and Diane. Sherlock doesn't ask his brother when he got married and neither is he offended by the lack of invite to the ceremony – he doesn't imagine there was one, really.
Mycroft's gift is a book.
He leaves it on the sideboard. It gathers dust.
He considers selling some of the honey but decides against it. It's not like he needs the money and he always was a bit of a hoarder. He gives some to Mycroft when he comes and ignores the way Mycroft eyes the book still sitting on the sideboard.
"He asks about you, you know."
Sherlock hadn't. Nor had he wanted to know. He looks up to Mycroft and then over to the book.
Mycroft retires a short while later and Sherlock takes up root on the chair and stares for over an hour at the book.
The spine cracks when he opens it.
So does his heart.
"To him whom I shall ever regard as the best and wisest man whom I have ever known.
Believe me to be,
Very sincerely yours,
The ink is fading and the paper thinning from where Sherlock continues to run his fingers over the words. He can feel the tiny flecks of rubbed paper come away under his fingers and he panics slightly at the thought that he could wear them out, too soon.
"I'll have to write you another one if you keep doing that."
He looks up to where John is standing in the doorway, tousled and rumpled from sleep. Sherlock hadn't heard him come down. He looks from John back down to the page, to the words that had found him back in London and speaking English for the first time in over ten years.
He snaps the book shut and drops it to the floor beside his chair and smiles as John moves towards him. He's older – they both are – and his French is as bad as the day they'd arrived in Lille fifteen years before and he's a kept man but he doesn't mind, and neither does Sherlock.
Sherlock smiles up at him and bends his head into John's hand when it combs through his hair (speckled with more grey now than he likes to admit).
"No need," he murmurs into John's palm when he turns his head. He presses a kiss there, too, for good measure. "Not when I have you."
He draws John down and they settle, a little awkwardly, on the seat and Sherlock ducks his head into John's warm neck and sighs as John brings his arms around his shoulder and sinks further into him.
It's not perfect.
But then nothing is.