A/N: Wrote this awhile ago while still trying to flesh out my Sherlock characterisation. It's interesting to come up with motivations for some of his more dickish actions. Try and make his behaviour make more sense, you know? Haha.

He flexes the arm with the patches, willing more blood to flow through the limb and up, up to his brain. The frenzied mess he calls a mind is beginning to calm and oh, it's glorious. Like a systems terminal shutting down, everything just stops. A million and one stray thoughts stutter to a halt and finally leave him in peace. Distractions, things and details and objects in the room that he usually can't help but examine suddenly all cease to matter. Nothing matters now. Nothing except the case, because the case is what he wants to think about and for the moment he can choose to do so. He is in control of his own mind and it's such a foreign state of being that for a moment he simply revels in the giddy high of it all.

Right, Sherlock, focus. He's got a good while before the initial buzz wears off but it won't do to waste it all just lying here watching the room spin. He closes his eyes against the dizziness and begins to think. Free from the distractions of his own mind and the environment around him, he can finally bring the full force of his deductive reasoning to bear.

And then John shows up.

John showing up doesn't necessarily bother him, he supposes. He can, after all, ignore the man. The absurd amount of nicotine in his system right now gives him the option to do that. But John asks him what he's doing and Sherlock finds himself responding. Banter, back and forth, and it's fun somehow. He doesn't need to guard his words or think about upsetting the man because John apparently doesn't get upset, not over silly things like manners. And quite frankly that's a good thing because Sherlock is not at all in the right frame of mind to navigate social conventions. Nicotine is not a talking drug.

John is just standing there now and Sherlock really doesn't care why, so long as the man's quiet about it. The detective closes his eyes again, brings his hands up under his chin like he's praying because the perfect symmetry of fingertip-to-fingertip feels good, and John is still standing there. Damn. What does he want?

Oh! Oh, right yes, he'd sent those texts. After he'd already put on the patches. He'd realised only belatedly that his number might be recognised, but going downstairs to borrow a phone was too risky. No telling when the vertigo would hit, and he had little desire to wind up in hospital with a broken neck (again). Not while a case was on. Tried yelling but Mrs. Hudson either didn't hear him or pretended not to. Well, no matter. He still had his phone. Played a bit of a psychological game, he recalled. A few carefully-chosen words to ensure that the rumpled ex-army doctor would show up eventually. It worked, of course. Things always seem to work when he's high.

John hands over his phone and Sherlock takes it. Holds it between his hands for a few seconds before remembering that the number he needs is across the room and he's certainly not getting up to retrieve it. Not without falling flat on his face, at any rate. He hands the phone back to John and tells him what to do. The man's dallying for some reason or other, Sherlock doesn't mind. It's not time-sensitive and he'd really just as soon ride out the remainder of his vertigo on the couch.

But then John mentions a friend? Friend! Oh, enemy. That's alright then. Plenty of those. Which one?

Ah. Mycroft. Well he'd expected it really. The meddling git. John's passed his brother's silly little test, obviously, or he wouldn't be here. Nice to know the doctor is trustworthy, but Sherlock still wishes he'd said yes. Just to wipe the self-satisfied smirk off Mycroft's fat face when someone failed to conform to his perfect little expectations. He tells John to think it through the next time. Knowing Mycroft there'll probably be one.

Thinking about Mycroft is annoying and so Sherlock simply doesn't. He gets John back on track instead, because the dizziness is abating and if he's going to sober up anyway they might as well do something useful with their time. The doctor does as he's told, military instincts giving him a pleasing predisposition to follow orders. He takes far longer than Sherlock would have and asks some obtuse question about blacking out which is confusing for a split-second because they'd only just met, how could John know-? But he realises a fraction later that the man's just being thick.

It's been a good ten minutes now and the initial vertigo of his three-patch problem is down to a manageable level. He doesn't give himself time to think, just springs up from the couch and steps over the coffee table resolutely. Doesn't fall flat on his face, doesn't vomit. All good signs. John has forgotten the address already and good god how? It's only been a few seconds! But Sherlock forgives him. The man's only ordinary, after all.

He makes his way across the room. Manages not to stumble in the slightest, (which he thinks he ought to congratulate himself for because the walls are still not entirely steady) and grabs up the victim's suitcase. Time to see if there's a brain hiding behind that boring, unassuming face.