Sherlock Holmes has always made it a practice to be the tallest person in the room, even when he isn't, but for Spencer Reid he suddenly finds himself willing to make an exception.

Their association began in a purely intellectual, if somewhat abrasive, fashion-as so many of Sherlock's do-when he published a response to one of Spencer's academic articles, pointing out the obvious flaws in his hypothesis. He had thought that there would be a bit of back and forth before Spencer proved himself to be both brainless and boring, but he had managed to surprise him. He not only penned a rebuttal, but neatly and concisely proved Sherlock wrong. After that, there followed a flurry of publications from both sides, which eventually turned into private emails because the journal's editor had enough and insisted that even aficionados wouldn't want to read that much about fingernails.

Articles became emails, and when the lapsed time between replies became too torturously long to wait, the emails became near constant texts that covered everything from cases to whether Elizabeth Wallfisch or Fabio Biondi was the better baroque violinist. If Sherlock felt a bit of a sting on those occasions when Spencer trumped him-'It couldn't have been the brother! You said yourself he was wearing a peach sweater!'-it was rather worth it to not have to explain his every thought process.

He's in the middle of a prolonged experiment involving a pig's bladder, industrial strength sealant, and a bottle of milky looking liquid-which he'd very nearly allowed John to add to his tea before deciding that whatever results doing so would yield would certainly not be worth all of the complaining John would do once he realized his taste buds no longer worked properly. After three sleepless days of poking and prodding and driving John out of the flat because of the very slight odor, he's quite near the point where even he might concede to needing a break, though certainly not because of any lack of mental clarity. Indeed, his thoughts are as sharp as ever, though his hard drive must be a bit cluttered since it comes as a surprise when Mrs Hudson ushers Spencer through the door of 221B Baker Street. He's fresh off a case and the plane, and if the smell or Sherlock's less than gracious greeting bother him, he doesn't show it.

Spencer's taller than Sherlock expected, at least two inches taller than himself. Worse than that, after only a few minutes of talking, it's apparent that his intelligence isn't a fluke. His mind is, loathe as Sherlock may be to admit it, very nearly a match for Sherlock's own.

Sherlock should be bothered to not have an advantage in some way. He's certainly always endeavored to find one before. His entire life, Mycroft has been towering over him, but even when the difference in their heights was at its most extreme, Sherlock's clearly superior intellect gave him an obvious foot up on his older brother. And while there's the distinct possibility that Moriarty may yet outwit him, Sherlock still has the pleasure of cutting a more imposing figure than the slighter man. But the fact is, he and Spencer are evenly matched in both intellect and form. It's vexing in a disgustingly human way that it even occurs to him to be bothered by it, but the fact remains that with Spencer by his side, he can no longer expand his presence, filling the extra space around them. Make himself just a little more there than Spencer is so that every eye will turn to focus on him, as it rightfully should. Normally this fact would drive him to distraction, but it's hard to resent a man who finds nothing unordinary about the decomposing jellyfish in your bathroom sink.

The visit is supposed to be short, more of a 'hello, nice to meet you' exchange of pleasantries. After all, Spencer is scheduled to give a lecture in the morning and if Sherlock leaves the bladder alone for too long, there's a very real possibility that it'll combust. Normally Sherlock would find that fascinating, but with John out and Mrs. Hudson refusing to go near any more of his 'questionable spills', he would have to do the washing up himself, which is a sore misuse of his considerable skills. So, a short visit it is, but even Sherlock's plans occasionally go wrong, and twenty minutes after Spencer says he'll see himself out in five, Sherlock is showing Spencer how he takes his tea as they discuss Ted Kaczynski. Forty minutes after that, Spencer's refilling a syringe for Sherlock to inject the pig's bladder with while they dissect the socioeconomic ramifications of the Industrial Revolution in minute detail. A half hour more and they've declared the jellyfish a bust, but agreed that the Egyptians were fools for disregarding steam power.

Three hours later and they're slouched on the couch, and no matter how convoluted or far reaching Sherlock's statements become, Spencer doesn't get tangled up by ignorance like most do. There are so many words that they keep tripping over them, and yet there's no need to explain or clarify or simplify. It's exhilarating, exciting, exhausting, and many other words that start with 'e'. There's something gratifying about speaking with someone without constantly wondering if they really see the whole picture with those mostly vacant eyes of theirs, but it's draining too. It's almost too much to take-too decadent, too overwhelming, too intense. His nerve endings tingle with the raw power of it, every neuron in his brain working overtime in a way they've never been forced to before. If this is how other, normal people feel all the time, then it's astonishing that more of them haven't gone around the bend! A world without language barriers, where he can speak without having to slow or outright stop so that others can catch up, which they sometimes never do, would be indecently wonderful.

They manage to keep speaking longer than should be possible, but by the very early morning hours, their words are coming slower, slurring together as they slip off their tongues, and their bodies are heavy and loose, and would probably have tipped over ages ago if they weren't leaning against each other. The last thing Sherlock hears as he slumps more comfortably against Spencer's side and his eyes start to drift closed is the other man mumbling something into his hair about seismometers.

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Written for the daily drabble exercise I do on my LJ. Answers the prompt "BBCSherlock/Spencer Reid - too tired to think."