A/N: Just a half-finished oneshot I found sitting on a flashdrive, thought I'd polish it up and post it. Originally written in response to a request to do a tag for TBB I believe.

* Edited some things based on friendly feedback and a lesson on ancient languages. Thanks! :)

It takes John a day and a half to notice the bruising.

Well, to notice the pattern of the bruising, in any case. Of course he'd seen that there were bruises, there just hadn't been any opportunity to investigate further until now.

He's no Sherlock when it comes to these things, so it takes John some time to realise that the red discolouration he'd expected to see after Sherlock managed to get himself nearly strangled down in that tunnel is, in fact, two distinct bands of red. One of which looks to be quite a bit further along the process of fading compared to the one on top of it.

The morning starts out in as typical fashion as any around 221B - John's sitting in his favourite armchair nursing a cup of tea and trying to ignore the various aches and pains his abused body keeps broadcasting at him. Sherlock, meanwhile, is pacing back and forth in his dressing gown near a haphazard pile of books by the shelf, mumbling phrases as he speed-reads through random pages of whatever tome he's got propped open in his arms. He'd ostensibly been re-organising the bookshelf (and to the man's credit a fair few are indeed back in proper order) but now seems to have gotten sidetracked, tearing through volume after volume searching for god-knows-what; a passage or reference or hell perhaps a dried flower... John has no idea and quite frankly he's got no real desire to find out.

He would, however, very much like to know about that bruise pattern. Maybe it's just the concussion messing with his mental faculties but John could swear there's something off about it.

"Why've you got two different bruises?" John eventually asks with a nod toward the general direction of Sherlock's neck, which is clearly exposed as the younger man hasn't yet bothered to change out of his pyjama shirt. Sherlock, true to form, doesn't seem to take any notice. That's fine with John for the moment - he's not about to get up and examine his irascible flatmate, after all. No, he's feeling quite comfortable sitting right here in his chair, thank you very much, and he very much doubts the mild concussion he'd sustained after being bloody pistol-whipped will take kindly to a bout of attempting to argue Sherlock into accepting medical assistance. (Guaranteed migraine-inducer if there ever was one.) So rather than make a fuss John merely stays seated and waits for the detective to acknowledge his presence.

It takes around fifteen minutes. Sherlock's flipping rapidly through a book that looks to be written in Latin, muttering to himself in a language that sounds like Japanese, when he abruptly freezes in place and shoots a questioning glance toward John.

"Did you say something?"

John smiles to himself, shaking his head in bemusement. Some days he could swear Sherlock's attention span works on nothing more elaborate than a simple queue system - just take your number and get in line, he'll come round to you eventually.

"You've got two sets of bruises on your neck," John points out for a second time.

Sherlock raises an eyebrow in apparent confusion, but then an instant later catches on. He lifts a hand to prod gingerly at the ring of red-and-purple marring the marble white of his throat, face twitching slightly like he's repressing the urge to wince. After a second he quickly drops his hand and returns his gaze to the Latin book with a dismissive gesture. "Oh! Yes, our smugglers appear to have been rather partial to strangulation as a murder technique. Bit common, really."

John's brows furrow slightly as he studies the marks criss-crossing his flatmate's neck. "When did that first one happen? Looks a day or so older at least."

"Approximating dates of injury from across the room now, are we?" Sherlock quips in a bland voice, a vaguely amused look on his face as he riffles through another few pages. His eyes seem to be scanning lines faster than John thinks should realistically be possible.

"Seems your insanity's contagious," John replies in an equally unimpressed tone, rolling his eyes slightly before fixing his gaze back on his flatmate. "Seriously though, when did that happen?"

Sherlock glances up from the pages again to blink quizzically at him, then flits his gaze upward like he's trying to remember something. A few seconds of silence pass before he shrugs and looks back down to his book again.

"Thursday, I think."

"You think?" John retorts with a baffled sort of half-gape. Sherlock shoots him a vaguely irritated look.

"I've rather more important things to bother with than keeping track of the date, John." He pauses as a thought seems to occur to him. "Come to think of it though, what day is today?"

"Saturday," John supplies automatically, still staring at Sherlock with an expression halfway between disbelief and exasperation. "The fifth."

Sherlock's face shifts into a look of bland, disinterested surprise. "Is it really? Hm."

And with no further comment he goes back to whatever he's reading.

"Sherlock..." John starts, meaning to address the whole 'not knowing what day of the week it is despite being a fully-grown adult with a job' issue, but he quickly cuts himself off. No, no, never mind - in retrospect that whole revelation isn't actually the least bit surprising. Sherlock forgets what year it is half the time, expecting him to know the date would just be wishful thinking. Still, John supposes he's allowed a little grace period in acclimatising to living with a lunatic. And there's the concussion, so...

"John," Sherlock suddenly intones, not looking up from his book.

John blinks himself out of his thoughts. "Huh?"

"Nothing, you said my name then trailed off." Sherlock finally snaps the Latin novel shut and fixes John with a steady (concerned...?) stare, eyes narrowing slightly as he scans the other man for details. "You're still concussed."

"Oh, right... yeah, probably am a bit," John concedes with a shrug and a slight wince for his head which is, indeed, continuing to throb with a dull ache. "Nothing to worry about though, I'm fine," he assures. Then stops.

I'm fine... something about those words seems oddly famili- oh! Oh, right, it was after...

"Soo Lin's flat!" he exclaims. Sherlock raises a questioning eyebrow for his flatmate's apparently random outburst, and John hurries to elaborate before he ends up carted off to hospital under suspicion of having had a miniature stroke. "That's when it happened, Soo Lin's flat! You went all croaky for awhile but you hadn't caught a cold, so..." John trails off again, the implications of what he's just figured out coming together in his mind like a jigsaw puzzle. "Wait, hang on, you were ambushed by one of the smugglers in there and strangled? That's why you were coughing the whole way to the museum?"

Sherlock quite abruptly looks uncomfortable. He fiddles with the book in his hands for a split-second before turning to set it on the shelf behind him - an action which conveniently sets his back to John. "I told you I was fine."

"Fi-? Sherlock!" John snaps angrily. "Strangulation isn't something you can just walk off!"

"An obviously false statement, considering my having done exactly that," Sherlock replies archly. He still hasn't turned back from the bookcase, now occupied with straightening and rearranging the few volumes he's managed to put back without getting distracted by their contents. After a pause he picks up a random text and flips through it, adding an annoyed, "multiple times."

John blinks. "What, you've been strangled before?"

"Yes."

"And you're saying just got up and went about your business, every time," John presses in a flat tone. Every medical instinct in his body is telling him to scold the idiot in front of him till his face goes red - trauma to the soft tissues of the neck is a serious bloody injury, requiring professional medical treatment. Picking yourself up and carrying on is how people end up dying of asphyxiation in the middle of the pavement when their damned throats swell shut.

Sherlock seems torn between wanting to abandon the conversation altogether and defending his actions. It takes barely half a minute for him to choose the latter.

"Four times, not counting these last two. The first... incident... occurred in an environment I had no control over, I had no choice but to behave as if nothing had happened. The second was nearly identical to the first except I was slightly older. The third time I was assisted by a good samaritan who assured I was breathing normally before I left to see to other matters, and the fourth..." He pauses, tilts his head as if he's just realised something. "Well, actually I suppose I did end up in hospital after that. Not for being choked, though."

"What... what for, then?" John asks somewhat blankly, doing his best to wipe the look of slightly dazed bewilderment off his features. For some reason he's never actually considered the fact that Sherlock's life prior to John arriving would most likely have been every bit as full of random violence as it is now. He knows Sherlock's capable of self-defence, obviously; but the thought of his skinny, easily-distracted flatmate fighting for his life alone against some massive beast of a suspect or a gang of street thugs... it's almost surreal.

"Just a cracked skull and broken ribs, I believe," Sherlock supplies in a tone that suggests he thinks things like bone fractures aren't particularly interesting or noteworthy, which is probably why he's forgotten the details. "Regardless, adding this week's episodes to the total means I've had no complications arise from choosing to just walk off five out of six strangulations, rendering your outrage provably unjustifiable. So kindly avoid lecturing me about it."

"Sherlock, I'm a doctor. It's my job to lecture people," John counters with an irritated scowl. "Why didn't you just tell me you'd been injured?"

"It was hardly any of your concern," Sherlock replies, beginning to sound a bit snippy. John pinches the bridge of his nose and bites out an exasperated sigh.

"If my friend is hurt I'd like to know about it so I can help." Honestly, this shouldn't even be something he needs to explain. At his words Sherlock turns back around and gives him a look like he's transformed into some sort of bottom-feeding vermin. John drops his hand with a questioning blink. What? What did he say?

"Well if one of your friends should come to find themselves injured in future I shall endeavour to inform you," the detective responds in a clipped, icy tone. He drops the book he'd been skimming through atop the haphazard pile at his side - causing the tower to collapse sideways in a heap of dust and old paper - and stalks off toward the hallway with a dramatic flick of his dressing gown.

John keeps his seat, still blinking in confusion. The hell had brought that on?

"Sherlock?" he calls after a moment. His moody companion doesn't respond, however, choosing instead to let the frigid silence of the flat answer for him. John tilts his head back and rubs a hand down his face in harried exhaustion. God's sake, would it be too much to ask to go five minutes without triggering some sort of incomprehensible emotional snit?

Finally he decides enough is enough - he's not letting Sherlock build up some ridiculous mental grudge without at the very least getting the overgrown brat to explain what in god's name he's miffed about this time. Besides which it's getting time for John's next dose of paracetamol and he's fairly sure he left the bottle on the nightstand by his bed. Groaning with the dull pain of a dozen abused muscle groups he shoves himself out of his chair and into a standing position.

Slight wooziness, greying of the edges of his vision... but nothing untoward, it'll sort itself. With a short grumble and a careful shake of his head he shuffles toward the hall.

By the time he makes it to the doorway he's begun to seriously regret the decision to leave his chair. Far more nausea than he's strictly comfortable with, and the wooziness isn't abating. Hand on the doorjamb he succumbs to the demands of his body and lets himself collapse on his rump into a sitting position, back to the wall behind him. Alright, wait, wait... hang on. Nothing but a head rush. Just a minutes' rest, then he'll get back up.

Next thing he knows he's blinking awake to find a pair of rather concerned-looking grey eyes staring into his, pale fingers snapping in front of his face.

"John, wake up," Sherlock mutters tersely. Seeing that John's conscious he lets his hand drop from where he'd apparently been trying to rouse him and goes for his wrist to check pulse rate instead.

"M'fine," John protests as too-cold skin meets the warm carpal vessels of his right arm, then immediately furrows his brows at the sound of his own voice. Had he just slurred that? Bloody hell, maybe he shouldn't have declined that hospital checkup back at the crime scene. "Hm, s'not good."

"No, it's not," Sherlock confirms in a clipped tone. "Stay here."

John doesn't exactly have a choice in the matter, uncoordinated as his muscles seem to be at the moment, but he doesn't bother pointing that out as Sherlock gets up and disappears into the sitting room. Low murmur of a voice, probably ringing someone. John frowns to himself as thoughts of ambulance rides and hospital visits flit through his head. This, he surmises in resignation, is going to be a very long day.

As it turns out his prediction wasn't entirely correct. It's a day spent being shuttled around places he'd very much rather not be, yes - waiting rooms and CT scanners and radiology labs - but it doesn't take anywhere near as long as he'd thought it would. In fact they seem to get shunted through each department with frankly alarming efficiency. Seems having a flatmate with the British Government on speed-dial comes with a few perks.

"Just mild swelling, no detectable bleeding or clots," Sherlock informs him as he flips through John's chart at the end of the hospital bed. John had acquiesced to the private room they'd offered (more like forced on) him, but refused the gown or IV drip on grounds that he's clearly not about to drop dead of a grade 2 concussion with slight delayed-onset oedema. He sits propped up with his back to the bed's overstarched pillows in his shirt and trousers with his arms crossed over his chest, fixing a stone-faced look of disapproval out on the world in general. Doctors make the worst patients, it's said... and for damned good reason. He hates being on this side of the medical relationship.

"Yeah, thanks, I know. I was there when they read the CT."

Sherlock doesn't seem to hear him, too busy studying what looks like the patient history page - technically not something he's even allowed to be snooping through, but John figures complaining about his right to privacy to Sherlock Holmes would do about as much good as asking the sun to set backwards and so keeps his vague irritation to himself. There's better things to be annoyed about right now, anyway... like the fact that he hasn't been cleared to leave yet. Where on earth is that nurse with his discharge papers?

After a moment Sherlock seems to grow bored of whatever he's looking at and hangs John's chart back up on the bed railing.

"You should have said something if your symptoms were worsening," he says after a moment's somewhat-awkward pause. John just shrugs a bit in agreement.

"Should have, yeah. Didn't notice much off until I was already on the floor though." He glances sidelong at Sherlock, who's about this close to actually looking nervous, and flashes him what his hopes is a reassuring smile. "I'll be well enough after some anti-inflammatories, no need to worry."

Abruptly Sherlock's expression shifts to some sort of aloof disinterest as he moves his gaze to the far wall. "I don't worry."

"Course not," John agrees with a slight roll of his eyes.

"You did have a point, however," Sherlock goes on. And John's left to furrow his brows in a perplexed stare because he quite suddenly finds himself with no clue as to what it is they're talking about now. Thankfully Sherlock seems to have predicted his confusion and quickly elaborates: "What you were saying earlier, about informing one another of recent bodily harm or medical distress. Given the level of inconvenience caused by your remaining tight-lipped on the matter it's come to my attention that future investigations would be better facilitated by a standing policy of prompt notification of all serious injuries."

Oh, John realises - back to this morning's discussion. Right. He rubs a hand over his forehead to ease the dull ache of concussion lingering through the medicine in his system.

"That's, er... great," he mutters tiredly. "Good policy."

Sherlock inclines his head. "Quite."

What follows would be a rather uncomfortable silence if John weren't completely accustomed by now to conversations with Sherlock tending to trail off into long stretches of quiet with little warning. John's never much minded, though, and he's not about to start now; in fact the lapse is fairly welcome at this point since it means he's allowed to lean his head back and relax instead of talk.

"John," Sherlock speaks up after a few minutes. John blinks out of the apparent daze he'd begun to fall into and rubs a hand over his eyes in an effort to wake himself up.

"Huh?"

Out of nowhere Sherlock's glaring down at him from his post standing by the side of the hospital bed. "Don't ever do that again."

John raises his eyebrows at the uncharacteristically stern tone of voice, then huffs a bemused laugh. Doesn't worry, my arse.

Shaking his head slightly he replies with a semi-flippant, "I won't if you won't."

Sherlock regards him dubiously for a moment... then nods once.

"Deal."