Disclaimer: I do not own Sherlock.

AN: Apologies for any OOC-ness. I got an idea, and I ran with it, but I have never written slash before so it may be terrible. For the record, head injuries suck and I know from experience.

John watches Sherlock carefully. The detective is stood in the centre of a crowded street, turning very slowly on the spot and inspecting his surroundings, searching for something out of place, something John can only hope he finds because the doctor hasn't the faintest idea what they are looking for and neither, it seems, does Lestrade, who is peering at Sherlock just as steadily; both are waiting for him to make a move to tell them what to do.

Sherlock barely moves, only shifting his feet to alter his viewpoint of the street with his eyes narrowed in concentration. He hardly seems to breathe and people are skirting around him, giving him strange looks, but he ignores them, or appears to; in reality he is inspecting every face as it passes, knowing he could read their life stories in the way they carry themselves, the jewellery they wear, their choice of tie – but he isn't looking for these things now, he merely scans for what he wants and moves on once he has determined his target is not there –

And then, out of the corner of his eyes, in a street full of movement, he catches sight of one person who looks different somehow, and he knows – without warning, he gives chase, and the culprit immediately begins to dart between members of the public swiftly, seeming unhindered by the cold, slippery ground. Sherlock races after the figure, hearing Lestrade and John several paces behind him; he is faster than them, and they drop back, slowed by the buffeting crowd. Sherlock and the suspect slalom through vehicles both stopped and moving, pushing aside civilians without a backwards glance, focussed on their goal; the killer's to escape, and Sherlock's to pursue.

The only reason Sherlock manages to keep the man in sight is his unequalled knowledge of the roads of London and accurate guesswork regarding which of the alleyways he is likely to choose as he flees. Lestrade and John are still following, at a greater distance now.

The frigid air burns in Sherlock's chest, which heaves with the effort of the chase and with the rush of adrenalin associated with it – the excitement pulses through his veins so he is barely paying attention to the treacherous ground and risks losing his footing more than once.

The man turns suddenly right and Sherlock careens after him, launching himself around the corner too quickly; for a moment, seemingly in almost comical slow-motion, his arms windmill through the air and his feet slide from beneath him as he falls sideways. His eyes widen with shock and he feels a searing pain as the side of his knee collides with the ice; his clothes tear under the friction and his arm is scraped along its length, jarring his shoulder. It takes several seconds for him to realise he has stopped moving, and the sickening crack that he heard was his head smacking against the pavement. He's dizzy now, and his vision swims.

He hears shouting, sees a figure run past him; he vaguely recognises Lestrade's shoes and wonders how the DI has managed to overtake him, or why there is another face in front of him, frowning its concern and speaking to him urgently. He blinks, and the face forms itself into the familiar features of John Watson, who is now holding up a hand with four fingers sticking up. Wait. No. Four fingers sticking up and three folded down? Sherlock shakes his head.

'Two,' he answers blearily, trying to push himself to his feet as his vision begins to clear. John makes a disapproving noise and tries to peer into Sherlock's eyes, checking the pupils as best he can in the poor light. Sherlock moves away from him, avoiding leaning on his bruised right shoulder. His coat sleeve is ruined, he notices irritably. He likes this coat.

'Sherlock – slow down –' John warns as Sherlock manages to stand, and sways on the spot. His leg and arm are both badly grazed and oozing red, but it is the scrape on his head which worries John; deepest at his temple, the injury is dripping blood onto Sherlock's shoulder, but the detective simple swipes at it to clear the distraction from his line of sight, winching with poorly disguised pain. He looks as though he is about to attempt to follow the now long gone murder suspect and Lestrade. John catches his arm and stops him.

'Let go,' Sherlock says simply, trying to tug his arm away, but he stumbles, unsteady. His head is throbbing and the entire right side of his body stings. He's twisted an ankle, possibly sprained his wrist and very nearly dislocated his shoulder. He thinks he may have concussion. But he needs to – what was he doing? Oh. The suspect, yes, of course – he should be getting on with that. Which way had they gone?

John doesn't let go of Sherlock's coat sleeve.

'Lestrade can get him,' he tells Sherlock, 'he knows who he is now, they don't need you.' It sounds a little harsh, but he doesn't want Sherlock chasing killers through the frozen streets of London if his slightly dazed expression is anything to go by; he can't get the sound of his friend's head hitting the pavement to stop ringing in his ears. John takes in the bleeding wound with a carefully medical eye. Sherlock needs to be checked over at a hospital, ideally, but he knows that his flatmate will refuse. Sure enough, when John makes the suggestion, he does.

'Doctors are idiots,' is his slightly slurred reasoning; John decides not to comment, and tries not to let it worry him that Sherlock is now unusually compliant as he leads the detective to a taxi and informs him they are going back to Baker Street.

'I'll call Lestrade,' John assures him; he knows it is a bad sign when Sherlock, leaning against the cab window, does not reply. 'Sherlock?'

'Hmm.' Sherlock replies moodily. His eyes are closed, and he winces visibly when they go over a speed bump. John pushes his concern away – it's only a few scrapes, nothing serious. He has nothing to worry about.

'Don't go to sleep,'

'I am not asleep,' Sherlock informs him as clearly as he can while he nods off.

'Sherlock,' John prods him; Sherlock waves a hand at John in protest, frowning, 'stay awake, Sherlock, I think you have concussion.'

'Probably,' says Sherlock,

'So you can't go to sleep, okay?'

'Sleep is boring.'

'I know, so stay awake. Do you know where we are?'

'London.' Sherlock still has his eyes closed. John has to keep him talking, to reassure himself the other man is still conscious. He rakes his eyes over the injuries once more.

'Where in London?' Sherlock opens his eyes slightly and squints out the window at the passing buildings and people, before closing them again.

'I don't know.'

Now, John is sure Sherlock has concussion.

How very typical; Sherlock Holmes, who can race around the city every other day after some criminal or other, place his life in danger in every way imaginable, refusing to eat or sleep when such human needs are a bore to him, take substances John doesn't want to ask about, jump between buildings and straight in front of moving cars, come inches from taking a potentially deadly pill just to prove his own intelligence, get himself half strangled or trapped in an exploding swimming pool with snipers aiming at him from every angle and still walk away, ultimately, unharmed, and his brilliant mind, his boundless energy, has been brought to a halt, however temporarily, by a stretch of treacherous black ice.

How mundane.

The journey to Baker Street is not long, but John can't help but spend the whole time watching Sherlock to make sure he has not fallen asleep. The shallower grazes have mostly stopped bleeding by the time they arrive, dark dried blood now covering the tears in Sherlock's pale skin, a much more welcome sight than the brighter red of before. The tissue from John's pocket that Sherlock is reluctantly pressing to his head wound is not doing a great deal of good, serving little purpose other than to stick to the injury like the grit still embedded there.

John pays the driver and hurries towards Sherlock before he falls.

'Don't walk too quickly,' he instructs; Sherlock huffs moodily, but allows John to guide him through the door of the flat and push him gently onto the sofa. Having John around is useful, he decides; he needs someone to patch him up after embarrassing incidents like this, he doesn't have the patience to do it himself. Applying antiseptic and dressings is just too tedious to entertain the idea when he is alone.

He should remove his coat and scarf, and tells himself to do so; by the time John has returned from...wherever he went to fetch first aid supplies (Sherlock is not entirely sure where they are kept, and concludes John must have hidden them to prevent their use in some experiment or other; he grudgingly accepts that this is probably a good idea) Sherlock is still sat in exactly the same position on the sofa, with the ripped fibres of his clothing getting caught in the cuts beneath them.

'Head first,' John announces, dipping a cloth into water and reaching forwards; Sherlock automatically leans back to avoid his touch. 'Come on, Sherlock, I have to do this.'

'Leave it, John, it's nothing. I've had worse,' Sherlock tells him dismissively, going to stand up. John pushes him back gently and starts to dab at the wound despite Sherlock's protests.

'It could get infected,' he says, as though explaining to a child, 'I need to clean it at least.'

Sherlock doesn't reply to this, but screws up his face petulantly against the sting of the cleaning process. John has warm hands, he notices, and his movements are gentle even if they are irritating and do cause his head to sting so much he draws a quick breath through gritted teeth.

His insides appear to be twisting themselves uncomfortably. Or, he thinks it is uncomfortable. But the squirming isn't entirely unpleasant, he decides, and the odd lingering tingle after John's skin makes contact with his own is not completely abhorrent.

This is a conundrum. He is sure these aren't symptoms of concussion, and thinking back, perhaps this is not the first time he has noticed them. His cheeks feel strangely hot at John's closeness; somehow, it is embarrassing. But he doesn't want John to move away. He doesn't understand it, and he certainly doesn't understand why John's face has become so fascinating or when it began to seem so interesting to stare at the doctor so.

Sherlock always stares at people; he watches, he observes, he deduces, and he uses his deductions to his advantage, be it to solve a case, to remove his own boredom or to manipulate people into doing as he wants them to do; usually a combination of all three. He's never watched a person just to watch, just to see their brow's furrow slightly in concentration, study as they bite their lip and cringe in sympathy when the antiseptic causes that bit more pain than before.

It has never seemed interesting just to watch, for the sake of watching, but Sherlock finds he cannot take his eyes off John.

Sherlock is oddly still as John dabs antiseptic onto his head, wiping away the blood to find the source, relieved to discover it is not hugely deep. His breathing seems slightly shallower than normal, but John puts this down to his injuries and irritation at being confined to a seat while John does such boring things as clear dirt from the streets of London out of the side of his friend's head.

'You've really knocked this,' he mutters as a way to break the silence, which is unusually awkward; Sherlock shifts a little in his seat, for which John is grateful. His utter statue-like stillness was starting to get unnerving.

'I'd noticed,' Sherlock replies dryly. He tries to raise his eyebrows, but judging from the sharp intake of breath, doing so is painful.

'And you couldn't have slowed down on the ice?'

'Boring. There was a murderer to catch, John, did you expect me to sit and watch him escape?' John sighs.

'No,' he says, 'but you could have a little more regard for your own safety.'

'Says the army doctor invalided home from Afghanistan after getting shot,'

'I had backup.'

'And I have you.'

It is stated simply and quietly, but John is touched by the sentence and cannot think of a way to reply; his lips quirk into a small smile against his will but he remains silent.

That smile is another puzzle, thinks Sherlock. Or, more specifically, the odd feeling in his chest when he sees that smile is a puzzle, a mystery he seems unable to solve, like his heart has swollen just a little, and he wants to smile too, but he buries the impulse. He likes it when John Watson smiles.

Sherlock's pale features twitch momentarily but then become still. John frowns and applies a frankly unnecessary amount of concentration to reaching for the butterfly stitches in the first aid box. They won't cover the whole graze, but they will hold together the deepest gashes until they can heal a little. It is the best he can do.

He spends rather longer than he needs to smoothing the first of the strips of dressing onto the cut, running his thumb over Sherlock's prominent cheekbone to make sure it sticks properly. Sherlock doesn't object to the prolonged contact, and John finds himself reluctant to end it. He gives himself a little mental shake, not sure where this sudden desire to have his hand on his friend's face has come from.

Inexplicably, he thinks of Sarah and feels guilty. Why should he feel guilty? He has done nothing to her. Well – apart from that date last night, cut short because of Sherlock's most recent break in the case. But she said she understood. She seemed happy to let him go, let him follow Sherlock and promise to make it up to her. She had even smiled and wished him luck.

But now he pictures her face, the smile seemed forced and stiff, and her glance at his phone, still displaying the text, was contemptuous. She was angry. She probably still is angry; it is hardly the first date to be delayed or cancelled because of Sherlock, and patient as she is, there must be a limit to the number of times she will stand for him leaving her alone, seemingly in preference of his flatmate's company.

Pulling his hand away from Sherlock with a little jerk which seems to startle the dark haired man, John carefully picks up another butterfly stitch, moving unnecessarily slowly.

He didn't leave the date for Sherlock, he reminds himself, he left for the case. He left so he could help catch a killer and save lives, he left for justice. But the guilt is still there.

Oddly, the thing he feels most guilty about isn't leaving her once, or any of the number of times he has in the past; it is the knowledge that he will do so again, and again, and whenever Sherlock asks him to. Grudgingly, grumpily, reluctantly, complaining and irritated, but he will always come when Sherlock calls. The thought should make him resolve not to do so, it should make him decide to say no every once in a while. But it doesn't.

Sarah is very pretty, she is intelligent, funny, and understanding; so why is the little flutter in his chest stronger when he sees the brilliant light of a case in Sherlock's eyes than when he sees her face? Why does he find himself preferring Sherlock's company over Sarah's? And why hasn't he moved his hand from Sherlock's cheek yet?

John's thumb leaves a trail of warmth on Sherlock's face where it has rubbed the dressing smooth, which lingers even when the doctor moves his hand away. Not really aware why he does it, Sherlock scrunches up his face as though he has an itch, and the corner of one of the strips comes away; John reaches out to press it back down and Sherlock finds himself pleased, for some reason.

He does not understand this.

He does not understand why he wants John's hand to remain there, or why for a man so content to sit on his own and talk to a skull, he always seems to keen to have John's company. John is ordinary. John is plain and John is simple; John is like everyone else. Boring.

Except he is not; John is extraordinary because he didn't tell Sherlock to piss off. John is interesting because he has not yet left Sherlock. John defies Sherlock's expectations because he hasn't yet taken Donovan's advice, because he refused Mycroft's offer of money after only a day of knowing him, because he shot a man to save Sherlock, whom he barely knew, because he walks away from dates and dinners and work for Sherlock, because he is still here. It makes Sherlock feel...he isn't sure what the term is. But he knows that he doesn't want the feeling to stop; he likes it.

John is not plain and simple and boring, but John is outwardly nothing special. He is...comforting, to Sherlock. And Sherlock doesn't know why.

Even stranger, he doesn't know why he suddenly finds himself wanting to close the gap, only a few inches wide, between their faces. This is interesting.

John, quite separately from Sherlock, does know what to label what he feels when he sees Sherlock, he knows very well what to call the feeling when he watches the brilliant man solve cases no one else could, he knows why he feels so desperately unhappy when Sherlock is in one of his moods. But he doesn't want to know; it makes no sense, he can't...he just can't.

What about Sarah? What about the fact that Sherlock is a sociopath? What about the fact that Sherlock is a man?

What about the fact that Sherlock's face is so very close to his and his breath is warm, his skin is cold and his eyes are searching John's so intently?

John moves forwards slowly, very slowly, almost unconsciously; Sherlock doesn't lean back, he stays completely still, his expression remaining exactly the same. It's not fair, John thinks, it's not fair that Sherlock should be able to sit there so calmly and not...not what? This is nothing; he is simply dressing a wound for a friend too stubborn to go to hospital.

So why is he that little bit closer to Sherlock? Why is his discomfort at their proximity so close to being all too comfortable?

Sherlock shifts in his seat and John jumps back guiltily, scolding himself furiously but silently, feeling his cheeks grow hot. What on Earth is he thinking?

But...but Sherlock doesn't seem...he looks disappointed when John leans away.

Then they are both moving forwards, ever so slowly, so it seems to take an age to be back within an inch of each other, two pairs of eyes darting across the opposite face nervously, searching for signs of regret, signs of discomfort or disgust.

Sherlock doesn't know why he is doing this, he never does anything like this, but he knows what he wants to do...perhaps doing so will be an interesting experiment...just to observe the effect on himself, of course, and to see John's reaction...

Lips meet.

John's insides are dancing, his head is spinning, he is breathless and uncertain and sure.

Sherlock is warm, he is comfortable, he is happy.

This is not boring.

And then it's over; brief and tentative, the kiss leaves both men reeling despite the fact their touch was only feather-light. Sherlock searches John's face for his reaction and finds it confused, but perhaps...or is he imagining it? A little pleased. John searches Sherlock's face for regret, and finds none.

He leans forwards once more, faster this time and holds Sherlock's face in his hands, kissing him furiously – Sherlock responds just as fast and knots his hand into John's short hair, forgetting to reason and analyse for a moment and catching himself just acting, just because he wants to, just because this makes him happy, and he doesn't care why.

John pulls away first, leaning his forehead against Sherlock's and feeling dizzy with confusion and overwhelming emotion he doesn't have the concentration to name right now. He doesn't let go of Sherlock.

'That hurts,' Sherlock speaks quietly, matter-of-factly; John grabs his hand away from the cuts on Sherlock's face as though he has been burnt and knocks the first aid kit sideways in his clumsy rush to move away, suddenly furious with himself, humiliated at what he's done, he feels himself going bright red and refuses to look Sherlock in the eye.

'Sorry,' he mutters.

'I didn't say I wanted you to stop.'

He is smiling. A real smile that John loves, that John can't help but mimic as he finds himself leaning forwards again; he doesn't bother to think as he crushes his lips against Sherlock's once more.

'Interesting,' Sherlock murmurs,

'Shut up.' John orders. Sherlock complies. There are far better things to do than to talk right now.