Disclaimer: I do not own BBC Sherlock.
A/N: This was for a prompt on the BBC kink meme. OP wanted Sherlock being turned into a child and John having to take care of him. It will eventually be Johnlock but not until Sherlock is back to normal. Enjoy!

John is at work tending to one of his younger patients who has to get a flu shot when he feels his phone vibrating in the pocket of his trousers. The mother sends him a sharp look that practically dares him to answer and he sends her a weak smile in reply, hoping that Sherlock - because it is, unquestionably, Sherlock who is texting him - hasn't blown anything up or got himself trapped in a large steel box while a group of men and their dogs circle around the outside. Which, you know, could actually be a distinct possibility because that's exactly what happened two weeks ago. Still, in the interest of keeping his job and a roof over his head he ignores it and continues trying to coax a sobbing child into handing over her arm for just one minute.

By the time mother and child leave half an hour late, John is exhausted. He's minus two lollies and plus one large bruise on his right shin. He closes the door and pulls out his phone, absently flicking to the right screen while he makes a couple of notes in the file. As expected, the text - actually, makes that texts, because there's a lot of them and every single one is from Sherlock in a state of perpetual boredom. After the last case Lestrade kicked him out of the Yard and swore that he wouldn't approach Sherlock for help for at least a month or until the hot water died down, whichever came first. So far he's been holding true on that threat and it's absolutely killing Sherlock, who is close but not quite to the point of begging.

We're out of salt. - SH

And milk. - SH

Pick up some goose blood on your way home. - SH

BORED. - SH

Mrs Hudson just dropped a package at the door. - SH

John. I need your help. - SH

Setting the pen down, John frowns and turns his full attention to the phone. Now normally Sherlock's version of "I need you" can be for anything from he's stabbed himself to there's an intruder in the flat trying to kill him to well, anything really. But for some reason this text makes John feels a little uneasy. It's the last one, there's nothing after it, and when he sends a text back asking what's going on there's no response. It could be because Sherlock has gotten involved in a case or experiment of some kind. It wouldn't be the first time he's lost sight of everything else when something new captures his attention. But after living with Sherlock Holmes for as long as he has, John knows he needs to trust his instincts. He calls Sherlock's phone. There's no answer.

"Damn it," John mutters, glancing at the clock. His shift is just about over, there's only twenty minutes left. Barring any last minute emergencies he'll leave on time. It'll take about half an hour to get home by tube, faster if he takes a cab. He tries to focus on his paperwork, glancing periodically at his phone as though he can will a response just by staring, but the twenty minutes crawl by and it doesn't beep. The second the clock ticks over John is on his feet and hurrying out of the room, not even sticking around to chat with the pretty new doctor Sarah recently hired like he usually does.

He hails a cab and gets in. "221 Baker Street as fast as you can," he says tersely, staring out the window. He makes another attempt at texting Sherlock and then sits there holding his phone, heart pounding. He's wound up by the time the cab pulls up in front of 221 and he tosses a handful of notes into the front seat as he leaps out and hurries up the stairs, unlocking the door. Mrs Hudson's flat is silent. She goes out with friends sometimes during the day, and although she'd never say as much John suspects it's more to get away from Sherlock's violin than anything else. He takes the steps as fast as he can and pushes the door open.

Sherlock's name dies on his lips as he gets a good look around. To put it kindly the flat looks like a bomb went off, which isn't exactly unusual. Papers, bits of Sherlock's experiments, and other random crap liberally adorn every possible surface. He's been after Sherlock to clean up for days but it all goes in one ear and out the other. There are still three full, cold cups of sweetened tea on the coffee table and Sherlock's dressing gown has been slung across the sofa, dangerously close to sliding off completely and landing in said cups of tea. John picks it up automatically and folds it, still scanning the room.

And that's when he sees it, the one thing that stands out as abnormal in an otherwise normal sea of chaos.

It, he, is a child, huddled in the corner of the room. Small arms are wound around skinny legs, which have been pulled up protectively against a tiny body. The boy, it is a boy, he can tell that much, is dressed only in one of John's jumpers, which is too large for him by far. One bony shoulder is poking out of the neck hole. Dark curls have fallen haphazardly over his face. John stares and stares some more, feeling oddly light-headed. He has the sudden feeling that he knows who this child is but he's desperately hoping that he's wrong. Because if he's right then life just got a whole lot more complicated.

"Sherlock?" he says in his gentlest voice, the one he normally reserves for little kids who are getting shots. He sets the dressing down aside, noticing the remains of an unwrapped package sitting next to the child about ten feet away.

The boy twitches at the sound of John's voice and the little arms tighten but he looks up. And there, there's absolutely no mistaking those curiously pale blue/green eyes, now looking too large in a tiny face that's all angles. "John," Sherlock says, voice too high and too frightened. "I may have made a small miscalculation."

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