John has no idea how to handle this situation. It is a feeling not entirely foreign to him, but that doesn’t make it any more comfortable.
The thing is, John can deal with children. In fact, he’d go so far as to call himself “good with children.” The curly-haired seven-year-old in front of him, however, is a whole other can of worms.
“Sherlock,” John says, very slowly. “What, exactly, did you just do?”
There had been a bang, a smell like burning hair and—for some reason—brussels sprouts, and a very bright flash of light. John had been reading in the other room, pointedly not looking at the massive wire-and-chemical-and-what-the-hell-is-that contraption that dominated the kitchen. He was not watching Sherlock flicking around the flat like a gangly moth on a Christmas tree, scribbling equations in the margins of the newspaper he claimed would one day “bring him to tears with sheer soul-crushing monotony” and rearranging the room, seemingly at random. John was sitting in his chair, reading his book, and waiting for the inevitable bellow of, “John, this bloody thing is hopeless. Come upstairs and distract me or I swear to all reason I will burn this place to the ground.” (He wasn’t really worried about Sherlock burning down the building. He’d heard it enough that it was merely his cue for some very welcome distraction-sex. In fact, it had become such an accepted cue that John dreads the day Lestrade calls them to track down an arsonist. Certain wires just don’t need to be crossed.)
So when John lurched into the kitchen, peering through smoke for Sherlock’s inevitably grievous injuries, to find the child sitting on the table, he was completely at a loss. The child, however is not.
“That should be fairly obvious. I have successfully made myself younger.” And damnit if the kid doesn’t give him that oh-so-superior look John’s only just begun to tolerate on a thirty-five-year-old face.
“Sherlock.” John is amazingly patient. “You cannot ‘make yourself younger.’ Age refers to the passage of time. Time, as you keep reminding me during Doctor Who, moves in a linear fashion—”
“Jo-ohn,” the kid whines. Whines! “I don’t mean chronologically younger. I merely mean that I have temporarily reverted to the physical state of a young child.”
“That’s what I said.”
The child (John cannot really think of him as Sherlock), looks at his hands, thoughtfully. “An hour or two, I think.”
John rubs his temples, as if that could possibly help with the splitting headache he’s certain is about to crash through his skull. “Why the hell would you want to, what, de-age yourself?”
The kid’s face lights up, and John can definitely see Sherlock. “Science, John!” He crows, waggling his eyebrows. On adult Sherlock, the effect would be manic. On kid Sherlock, it is possibly the most adorable thing John has ever seen.
“And don’t worry,” Sherlock continues. “I still have all my memories. All of them.” He stares at John, waggling his eyebrows suggestively this time, and John’s mouth drops open.
“No, no, no, no. No, you do not talk like that when your seven bloody years old.” Sherlock giggles. John panics, grabs him by the scruff of the neck, and drags him into the hall cupboard. Sherlock yelps as John slams the door, leaning against it and trying to control the color of his face. Sherlock’s current … form and the … activities that the two of them had gotten up to this morning were two very separate things. And needed to be kept very. Far. Apart. Preferably forever. John really really hopes he hasn’t just accidentally deleted his ability to have sex for the rest of his life. He wonders whether murdering Sherlock as a child would be worse than murdering him as an adult. It would certainly be easier.
“Have you finished plotting my death yet?” Sherlock’s voice, at least an octave too high, sounds muffled by his ridiculous collection of swoopy woolen coats. (Oh yes, he has multiple coats. He claimed they were different, but John was completely convinced that that was either a bad lie or self-delusion. He has a coat problem. They’ll deal with it later.) “If I say I’m sorry will you let me out?”
John groans and opens the door. Little Sherlock is smushed between two coats, looking up at John with a pair of grey eyes that he probably hadn’t grown into until he was at least nineteen. He looks like pouting baby owl, or a Japanese cartoon. John sighs and steps back, yanking the kid out of the cupboard.
“Look. Sherlock. You did something scientific and impossible and I’m happy for you. Really, I am. But it’s kind of freaking me out. And I don’t want to leave you unattended while you’re seven, because I would not trust a seven-year-old with whatever the hell that is in the kitchen. So how about you sit down and read a book, or, I don’t know, write up your findings or whatever. Quietly. And wait for this to wear off.”
Sherlock sticks out his tongue. John sighs.
“Come on, kid.” Grabbing his book from the coffee table, he flops down on the couch. Sherlock narrows his enormous eyes for a moment, then tucks himself on to the couch next to him. John does not feel at all satisfied, because he definitely had not chosen the couch over the chair for precisely this purpose.
Sherlock pulls the closest laptop up into his lap (whose laptop it is hardly matters anymore) and begins to type. After a few moments and some frustrated noises, he bursts out, “Buggering hell!”
“Language!” John responds, really more habit than anything. Sherlock glares at him.
“My hands are too small.” He holds one up. On a reflex, John holds his out for comparison. He is by no means a large man, but his hand dwarfs Sherlock’s. He’s right, they’re tiny. All of Sherlock seems ridiculously small. John supposes he was quite small before shooting up like a beanstalk sometime in his teens. “I can’t type properly,” Sherlock says indignantly, looking at his fingers as if they’ve betrayed him.
“What if you write longhand now, then type it up when you’re bigger?” The sentence is absolutely ridiculous. Sherlock gives him a withering look.
“It’s a program John. I can’t enter data longhand into a bloody computer program!” He slams the laptop and tosses it onto the table.
“Oi! Careful there! You won’t be able to enter anything if you smash the damn thing. Look, we’ll watch some TV. You’ll be bored, I’ll be distracted, it’ll be fine.” He grabs the remote and flicks it on to the first thing he can find.Mythbusters. Sherlock doesn’t mind that show, though he is offended by the cavalier attitude of the “so-called scientists.” John has a few choice words about cavalier attitudes towards science, but he keeps them to himself. For now. Sherlock gives a grunt that could either be annoyance or satisfaction and settles himself against John’s side.
“I wish we had a case,” Sherlock mutters. John laughs shortly at the images of tiny Sherlock bossing around a group of nonplussed Yarders. “I’d have no trouble with those ducts we got stuck in last month.”
“Yeah, but everything else would be a bit of a chore. Especially, you know, talking to people. And tackling them. And— Well, all of it. Besides, if I took you to a crime scene, Lestrade and Company would all assume you were your kid. And then you’d be plagued by awkward questions for the rest of your life.”
“Everyone thinks I’d be such an awful father. I really don’t think it’s fair.” Sherlock crosses his arms and glares at the TV, as if the Mythbusters team themselves had made the accusation. Having this conversation with a primary schooler is so beyond bizarre that John cannot help a brief giggle fit. Sherlock continues to glare.
“I don’t think you’d be so bad,” John manages, once his giggles have subsided.
“No?” Sherlock looks intrigued.
“I’m not proposing anything, Sherlock. I know you like to take things and run with them. I’m just saying, I think you’d actually be quite good.” Sherlock narrows his eyes for a moment, as if he expects a “but.” When there isn’t one, he nods sharply and turns back to the TV, trying to hide a grin.
They watch in silence for the rest of the episode. When it cuts to commercial, John looks over to find that Sherlock has fallen asleep against his shoulder. And he looks so small and content that John just can’t help pulling the ratty old afghan off the back of the sofa and tucking it around him, or shifting so that the little body fits just so under his arm. He turns down the volume and allows himself to drift. When he wakes, Sherlock will be himself again, too-long limbs trying to fit in a too-small space. He’ll be manic and smug, as always, but good-humored and devoted and ridiculous and surprisingly patient when it counts, and sweet and protective and vulnerable and, above all, brilliant. Utterly, heart-stoppingly, impossibly brilliant. John closes his eyes and imagines his Sherlock walking in the door, squeezing on the couch so the little boy is nestled between them. John smiles. There will be time to talk about all of this. Time enough for anything.