A/N: Someone asked me to do this scene, so here we are! It was really fun actually! Uses a bit of my personal headcanon concerning Sherlock's sexual orientation though, which might fluster some people. It's just my characterisation, guys. Don't get all upset.

(P.S. I just have to point out that the laboratory set they use for this episode is hilariously cringeworthy if you've ever actually worked in a wet lab. So many H&S violations, good lord...)

Adjusting microscopes is always so finicky.

Granted, of course, it's still one of his favourite laboratory tasks. A bit like tuning a violin, really - endless careful tweaks, twist the tiny pegs just enough to see if the change is a good one then back off until the image comes into focus. One of those few activities where perfection is an attainable goal... where you know you've hit the right spot, and that makes the tedium bearable. Always best when there's a set endpoint, not just working and working for no tangible benefit.

At the moment he's busy trying to get the pollen specimen he's isolated centred in the lens frame. Slide's in the correct position (finally) and now it's down to focusing the lenses. John's on the other side of the lab bench, talking for some reason. Sherlock's not quite listening (no no, that turn was just a hair too far, back up a bit, switch to the coarse-focus knob, is that better? slightly, back to the fine adjustment then) but he still manages to catch enough of the other man's sentence to respond with a questioning noise. Not that he particularly wants John to repeat whatever inane thing he's on about now... but telling his friend to shut up would only irritate the man, which would be considerably more distracting than simple polite discourse, so he obligingly goes through the motions of humouring him. Sherlock's capable of multitasking, anyway. Carry on a conversation and focus his sample at the same time...? Fine, easy enough.

Regardless his voice ends up coming out as a bit of a distracted mumble when he replies to John's question about the hostage. Not how he'd intended to sound... but honestly he's busy. And anyway the topic's hardly relevant, is it? No possible leads to be had chasing after some random civilian plucked up off the street, really not worth getting sidetracked over.

John continues to talk anyway. Sherlock's far more interested in the readout screen of the pollen analysis to his left. No matches? Impossible. It's likely just not focused correctly. But if it's still off it's only going to be by a tiny margin, try the slide adjustment again... no, wait, back to the eyepiece... ugh, his phone chimes in his lapel pocket as he's working. Bugger it, he's bloody busy!

Generally he'd just ignore the message. Considering the magnitude of the case they're working right now though... well, there's a good chance it's something important. Should really take a look at least. But then the pollen analysis isn't exactly going to wait either (he's already got the comparison programme running - the longer the sample remains out of focus the more chance of missing the correct match, and re-scanning the entire database will waste time they can't afford). John's not doing anything useful anyway so he asks the man to retrieve it for him. Practically punches him in the chest trying to fish it out - careful, for god's sake! He's still got his hand on the microscope knob! One nudge will undo minutes of tedious focusing work.

Text from your brother. Ugh, of course it is. Delete it. Mycroft's perfectly capable of solving his own little idiotic problem, why can't the stupid prat just leave them alone for once? John for some reason feels the need to object. And oh honestly it's clearly not a matter of urgent national importance; Mycroft's not about to waste time texting his little brother over and over again when he actually wants something done. No, the man loves the sound of his own voice far too much to ever forego the opportunity to harass Sherlock verbally. But he's had a toothache for awhile now (too many sweets, probably) so this must be the day he finally relented and scheduled a dental appointment. Not an emergency visit, didn't cancel it, meaning the missile plans aren't critical. Obviously.

John seems irritated by his nonchalance. Lives are at stake? Pah, lives are always at stake. The world's full of billions of fragile little human beings all dying each and every second, it's impossible to care about them all. Why John insists on trying anyway Sherlock will never understand. Because really, why cause yourself stress worrying about the life of someone you'll never meet, whom you have absolutely no hope of ever assisting? From a perspective of net suffering it's practically the worst possible course of action - now not only is some complete stranger in pain, but so are you. That's twice as much distress. How is that in any way helpful to anyone?

No, better to not react at all. Especially if, as in John's case, having an emotional response renders you completely bloody useless.

Sherlock's distracted from his somewhat-scathing reply to John's nagging by the database alert. Match found! Finally! Now they can get some actual work done. Molly walks into the lab just as he's exclaiming in triumph, with some timid fellow trailing along behind her.

Sherlock eyes the newcomer for a moment. Ugh... no, he decides, he's really not in the mood to try and navigate acceptable social interaction right now - this is the time for brainwork, far too critical to waste cortical power trying to switch gears into something approaching polite conduct. John will handle it though, he always does. With any luck Sherlock won't even have to bother talking at all if he manages to make himself look sufficiently busy.

So despite the database match having already been completed he leans forward and begins pointlessly re-focusing the pollen sample again. Nudges the fine-adjustment, fiddling with knobs as he watches the image through the lenspiece blur and sharpen and blur again. Molly will leave quickly enough, he surmises, and then they can get back to working on the case.

But a whole minute passes, and ugh why is she still here? Introductions. Why does everyone always assume he wants to know peoples' names? Random arbitrary mixture of sounds used to indicate one of a billion faceless masses of human beings - it's information tailor-made to be deleted. And yet they all insist on telling him anyway. Usually while knowing full well he's only going to forget again in half a second which of course is rude so it just turns into another round of let's lecture Sherlock for being more mentally efficient than we are. Bloody irritating.

The coiling knot of annoyance beginning to burn through his skull at Molly's continued proximity takes up the majority of his mental space, so that when she starts going on about office romance and he glances over to the man beside him - sees the eyebrows, manicure, t-shirt, underwear - he blurts out his deduction without thinking. Gay.

It's written all over the man's face, honestly.

But then Molly goes stiff - sorry, what? and Sherlock realises a fraction too late what he's just said, how it's going to affect her. Oh for god's... she'll get upset now, won't she? And then she definitely won't leave. No, plus they'll probably all be cross with him... John especially and ugh why again is it not socially acceptable to just tell people to leave him alone? It would be so much easier. He could even have a little warning placard like blind people have: "NOT INTERESTED IN YOUR BORING LIFE, GO AWAY". Save everyone the trouble of getting offended when he inevitably cocks up at their pointless little game of social graces.

There's no cardboard handy to fashion a sign though, so instead he quickly backtracks. Covers the mistake - er, hey - and throws in a fake smile for good measure. There, god. Let John say he never made an attempt to be polite. Actually quite frankly that was a stellar effort considering the circumstances. Maybe they'll leave now...?

The gay man's flustered, knocks over a sample pan (very deliberately) and oh lord are you serious. Sherlock barely manages to contain an exasperated sigh as he rolls his eyes. Hiding a note under a dropped item, really? In what universe does that constitute acceptable flirting behaviour? Are you a grown man or a bloody schoolgirl?

Irritated beyond belief now, but rather than give in to his impulse to start berating the stupid idiot for being a pathetic spineless twat (and for behaving in as obnoxiously gay a manner as possible - he knows twinks are an acceptable facet of the culture but it's just so annoying) Sherlock instead turns his attention back to the microscope, determinedly ignoring the lot of them. Maybe a bit rude, yes, but a better alternative to opening his mouth right now. John should be thankful for his restraint.

Joe (was that his name...? no, no.. something with an I... oh who cares) mercifully says goodbye and leaves, but Molly stays behind. Oh, she thinks they're together. Right. The bloke wearing fluorescent pants above his trouser line is dating Molly. Still the girl's a friendly enough acquaintance so Sherlock makes at least some effort to keep the conversation civil. She's put on weight, he notices... usually loses it when she's stressed - forgets to eat, buries herself in her work - so the companionship must be beneficial. That's good, right?

Evidently not. She retorts with a flustered two and a half. No... three pounds, definitely. See? You're obviously quite happy, that's all that matters. Continue on with your little delusional romance and kindly leave me the hell alone so I can get back to my work.

But of course she doesn't. Tries to argue with him instead - he's not gay! ... and now for some reason John's decided to jump in as well? Puts a bit of product in his hair? Oh please. Shampoo is not product. As if either of them have any idea what they're even talking about.

He can't help smirking to himself in slightly bemused exasperation as they continue to lob useless defences his way; it's all a bit ridiculous. Because really quite aside from the whole I'm a bloody observational genius thing Sherlock's quite certain he's the only one of the three of them who has any experience whatsoever with spotting homosexuals. It's not exactly rocket science, of course, but accuracy does improve with repetition.

Briefly he toys with the idea of saying something along the lines of I've been to more gay bars than the both of you combined, but decides against it. He's not entirely certain either of them even knows his orientation... it's not like he makes a big show of it, after all, and this really isn't the opportune moment to 'come out', as it were. Besides which he rather prefers to let people assume he's asexual. More imposing, mysterious... and more importantly less likely to find himself being chatted up (and ugh god yet again, leaving a number under a dish? that's just bloody stupid) or, worse, fawned over by the irritating gaggle of young women who always seem to want to cluster around homosexual men.

So he instead just rattles off all the details he'd noticed (will they get suspicious if he mentions the underwear? no, apparently not, just another one of the million facts he knows - where on earth do they think he learned something like that though, he wonders, if not from experience?) and for good measure makes a token attempt to warn Molly off what's quite clearly a doomed relationship. Cat's out of the bag now, anyway, so it's probably better in the long run if she just breaks it off now.

Molly bursts into tears and runs out of the room.

Sherlock's expression drops into vaguely disappointed bafflement as she goes. What...? Crying? Why? Was that really so rude? He'd made a legitimate effort to be gentle about it! Even after she'd practically forced him into explaining himself - he still hadn't called her an idiot for not noticing, didn't make any suggestions about the clear level of desperation necessary to have fallen for such a ruse... even remembered not to bring up the weight thing again (and come to think of it she's probably going to drop at least five pounds after this). That's a bloody crowning achievement considering his usual level of tact when dealing with peoples' sordid little love lives. Molly should know him well enough to see that, shouldn't she? Does the fact that he tried count for nothing?

And plus he's just saved her a terrible, emotionally devastating breakup later down the line when what's-his-name finally confesses. Put the power to end it all in her hands rather than his. That's better than allowing her to suffer under a delusion for who knows how long... better than letting the revelation crush her when she least expects it.

John doesn't agree, evidently, and for the second time in five minutes Sherlock finds himself the subject of the doctor's steely disapproval. That, apparently, wasn't kind. Sherlock frowns to himself. God, this has really just not been his day for getting social mores correct, has it?

Well... whatever. It's not like he isn't used to accidentally offending people. Anyway enough with the nonsensical arbitrary rules of human interaction for today, far past time to move on to more relevant matters (and more importantly on to things he's actually capable of understanding, though of course he doesn't say as much - never admit to confusion, act like it's a choice). There's a case to be solved, hostages to rescue, shoes to examine... oh, speaking of.

He turns to the trainers on the lab bench beside him, angles one toward John.

Go on then.