A/N: So both of my long-format fics are being stubbornly difficult to write at the moment, and to prove I'm still alive I thought I'd do a short little thing about relapse. Turned out to be pretty interesting to try and describe the whole weird, complicated, frustrating process in a way that would hopefully be halfway readable. Warning for lots and lots of angst.

At first it's just good sense.

A difficult case, been awake for two and a half days straight. He's so bloody tired but there's no time to sleep. No, lives are at stake and if he succumbs to human weakness, caves to the demands of his pathetic husk of flesh and bones, then those children will die. Not enough nicotine in the world to keep him alert at this point, and he's become so tolerant to caffeine over the years the chemical might as well be inert. But then this is exactly what he keeps the emergency supply around for, isn't it? For emergencies.

And it works. The case gets solved, the children survive, everyone congratulates him on a job well done. Awed by his intellect once again, even John's impressed. I just don't know how you do it, Sherlock. I honestly don't. I can barely string a sentence together after one night without sleep, let alone bust up a human trafficking ring.

Sherlock doesn't tell his flatmate the truth of how he'd managed such a feat. Not because he's ashamed, though, because he isn't in the slightest - he'd simply done what had been necessary, nothing more. It's just that it's really none of John's business. The doctor would only get upset and Sherlock doesn't feel like dealing with the disapproval, the lectures, the concern.

And besides which it won't matter in the long run, because this had just been a one-off. An emergency dose, to solve an emergency, and that's it. There's no reason to fret over the incident.

But then soon enough the next case rolls around. And this time he's only been awake for about thirty hours before a glance at the fireplace - at his secret supply hidden behind the brickwork - makes him pause to consider his options. The impulse blossoming through his mind is an absolutely terrible idea, he knows that all too well. Shouldn't even be thinking about it. But then again... the faster he deduces who the murderer is the less chance that another victim will emerge. And that's the ultimate point, isn't it? Not letting anyone else die? Plus isn't John always nagging him about caring?

Well, he reasons, this is how he cares - getting things done quickly and efficiently so that no one else will suffer. Makes perfect sense really.

And besides, he reminds himself as he digs out the old, familiar black case containing a phial and needles... it's only the once.

That case takes longer than he'd expected. By his dozenth only the once (necessary, now, as he can't afford to let himself crash in the middle of work) he's begun to accept the fact that he's made a rather poor decision. But even then the thought doesn't really bother him - it's just so much easier this way. Everything calm, thoughts falling in perfect logical symmetry and the world muted to such a comfortable level of stillness around him. It's enough to make him wonder why he ever wanted to quit in the first place.

Then the case gets solved, the impetus for keeping himself buzzed erased. Now he has no excuse for not letting the drugs wear off. He's not some pathetic junkie anymore, so he does as he rightly should and dutifully puts everything away with nary a twinge of apprehension for what he knows will happen next.

Withdrawal, of course, but it won't be so bad. He's been through it so many times before, after all, always came out alright in the end... it'll be fine.

Soon enough he's snapping at John through a vicious migraine, snarls at Mrs. Hudson, resists the urge to punch a hole through the drywall as he retreats to his bedroom to curl up under the duvet in misery. And good god, now he remembers with horrible, agonising clarity - this is why he'd quit. Because his brain feels like it's about to melt out through his ears and the entire world is clouded by a fog of exhausted, neverending piercing torment. Fuck cocaine and fuck every single stupid neuron involved in making the idiotic decision to use it again. He's never ever going back on the stuff as long as he lives.

But even as he thinks that he knows it's an empty promise. He'll forget the pain, forget the haze of despondency and anger and guilt. Hell, by tomorrow morning he'll be mostly back to normal, if perhaps a bit tired. Caffeine and a nicotine patch to wake up, then, and the combination of dopagenic stimulants will erase all memory of this torture. His legal alternatives will mute the unpleasant side-effects of harsher chemicals while at the same time strengthening, sharpening his recollection of the high.

And eventually it won't seem like a bad idea anymore. Withdrawal will fade away until it's just a nebulous reminder of something unpleasant, nowhere near the level it needs to be to put him off doing it again. He knows this because it's happened before. Because it happens every single time. And the fact that he can so accurately predict his own future stupidity is, quite frankly, bloody depressing.

Even more so when it inevitably comes true.

This time there's not even a case. He's just bored. Bored bored bored and John's out at the clinic, Mrs. Hudson's off visiting her sister, Lestrade's on holiday, Mycroft's busy doing something and hasn't taken kindly to being texted over and over again in hopes of annoying the fat git into coming up with some fake goose chase of an investigation to make it stop. ('Sherlock if you message me one more time I will disconnect your mobile and internet for a fortnight. - MH') Sherlock sits curled up in his armchair and wonders what on earth makes them all think that leaving him alone in the flat for an entire day is in any way a good idea. But then he quickly reminds himself that he's a bloody adult and he doesn't need supervision.

Except he sort of does, really. Because there's absolutely nothing at all to do and lacking any decent distraction he finds he's been staring at the loose brick in the fireplace for a good twenty minutes now.

Despite his own better judgement he begins to weigh the pros and cons. Withdrawal will be uncomfortable, yes, but it's not that bad. And when compared with the blissful serenity he knows will come of using... well, it's hardly much of a trade-off, now is it? He'd be focussed enough to start a new chemistry experiment, maybe, or even clean the flat. (Well alright, probably not clean the flat, but perhaps tidy up a bit. John would appreciate the attempt regardless.) Doesn't even have to be a whole dose - just a few milligrams. A tiny amount. Enough to supplement the nicotine, nothing beyond that.

It occurs to him some forty minutes later that he is an absolute pushover when it comes to convincing himself to do stupid things. Those arguments had been bloody moronic. And yet despite the inanity here he is... quite happily high, actually, so maybe he doesn't mind all that much.

But he will mind. Later, when he's crashing. He knows that. Knows he'll mind quite a lot really. Then he'll be absolutely furious with himself. It's interesting how he can predict such things even now, while verging on being completely shitfaced, and how at the moment it all just seems sort of funny. Later it won't - he knows it won't. But right now it's amusing. It's hilarious. Chemicals do such strange things to the brain.

He chuckles to himself and adds another drop of potassium ferrocyanide to the mixture in the beaker on the kitchen counter. Well, whatever. He's got a good hour or so before it'll start bothering him - might as well make the best of his high while it lasts.

Another hour passes, and since the first dose really hadn't been very much he decides it'll be fine to do another hit. He's still in the middle of his experiment anyway, and the growing headache had been too distracting to continue handling the chemicals safely. Plus John won't be home until the morning - the man had called some twenty minutes ago to say he was staying over at his current girlfriend's place. (The pudgy one with the big nose, if memory serves.) Sherlock had cheerfully told his flatmate to have a lovely evening and gone back to his chemistry setup.

Half a dozen iterations of just one more hour, then I'll let it wear off creep by before he realises it's now past midnight and he's managed to incrementally nudge himself into quite the impressive cocaine high. The crash is going to be absolutely horrific. But maybe it won't be quite so bad if he instead titrates off. Halve the next dose, quarter the second... then instead of crashing he'll come down in stages. It seems like an excellent plan. Which truthfully doesn't mean all that much because everything seems like an excellent plan right now.

And that, he reminds himself in a tone of thought which should have been stern but which comes out more like giddy amusement, is exactly how cocaine works. It makes the world silly, free of all worries, consequences lose meaning until they're absolutely pathetic and nothing in the entire universe is outside his control. But still underneath it all is a tiny voice screaming through the ice - you idiot, none of this confidence is real, it's just the chemicals! Everything is going to go to absolute shit in a few hours and it's all your bloody fault!

It's so easy to drown out the yelling though; so simple to just ignore it and go on with whatever he's doing. Which... at the moment is nothing? Oh, he'd finished his experiment. Predicted results, calculated data, recorded it on the website. Hadn't even noticed. Well, maybe he'll go for a walk then. Wandering the streets of London in the middle of the night? Brilliant, sounds like fun.

By the time he returns to the flat it's been well over six hours and he's exhausted. John is home, sitting in his armchair reading the paper, not dressed for work, must be his day off, Sherlock doesn't care. The entire world's gone back to being awful and he just wants to sleep forever.

"Out on a case?" John asks, looking up from the news as Sherlock walks into the sitting room. Sherlock grimaces at the sunlight filtering through the window and rubs at his forehead, trying to ease a migraine he knows won't go away until he either sleeps or does another hit of coke. John is here, though, rendering the second option infeasible. Which really begs the question of why he'd even bothered coming into the sitting room in the first place, as his supply is still hidden by the fireplace. What, had he thought John would fail to notice if he just walked over and removed the loose brick? The man's ordinary, yes, but he isn't blind.

John's still staring at him expectantly, so Sherlock forces himself to ignore the pain in his head and responds in as casual a voice as he can manage. "No, I just went for a walk."

"In the middle of the night?" John's expression is somewhere between bemused and exasperated - fairly standard when interacting with his erratic nutcase of a flatmate. Under ordinary circumstances Sherlock would just shrug it off, reply with some quip about normal people and go about his business. Right now, though, he's in pain, and frustrated and tired and angry... doesn't want to fucking deal with John's stupid condescending disbelief. Why should it be strange that Sherlock went out for a walk at midnight? There's nothing bloody odd about it. Stop making that damned face, you fucking git.

It occurs to him belatedly that he's scowling venomously over at his flatmate. John's starting to look slightly concerned, like maybe he thinks there's something wrong. There isn't. Really there isn't. Nothing's going on at all.

No, everything's normal, Sherlock thinks pointedly, loudly, as if hoping his message will somehow travel the empty space between them through raw willpower and then he won't have to bother trying to form the right words to put John off the trail. I haven't done anything stupid, just made a few slightly inconvenient decisions. But I can handle it, it's fine. Fine fine fine. I knew exactly what would happen. Oh and by the way you're sitting right in the bloody way of me getting to my secret supply and that's making me want to punch you in the face, but I won't because I'm not that pathetic.

I'm not.

John's still looking at him. Sherlock forces the glare off his face and turns to head toward his bedroom. "I'm taking a nap."

"It's six in the morning," John points out. Sherlock grits his teeth against the urge to turn back around and shout at the man.

"I know what bloody time it is," he snaps acidly instead, then stalks off through the doorway and down the hall.

Sleep. Sleep will make it better. Then he'll be fine.

Hopefully.

««

When he wakes up he still has a headache.

Cocaine would make it go away (a fact he knows with frustrating certainty) and nicotine, while not entirely effective, still might ease the discomfort somewhat. Paracetamol probably wouldn't do much of anything but could be a good idea regardless, take the edge off. Especially if ingested in conjunction with caffeine. But then no no no, he's not falling into that particular trap again - drugs over drugs, swallow the cat to catch the mouse. Never leads to anything good.

Chemical abuse put him in this situation in the first place, he reminds himself, and adding more substances definitely won't solve the issue. Actually the better option would be to simply force himself to suffer through the consequences - unpleasant, yes, and undeniably painful... but maybe if he just endures the discomfort this time it'll finally manage to stick in his brain and serve its purpose as a proper deterrent. It probably won't. In fact he knows full well that it won't... but maybe.

At the very least the decision helps him feel less like a pathetic addict. Because a proper junkie wouldn't willingly avoid drugs for the sake of teaching themselves a lesson, now would they?

He tactfully chooses to ignore the fact that if there's ever been such a thing as a proper junkie he's been more or less the textbook definition since the age of nineteen.

John's still in his armchair when Sherlock gives up on going back to sleep (head hurts too much, can't keep still) and instead wanders into the sitting room. The curtains are open, stabs of pain pulse through his brain from the light outside, but he doesn't move to close them. No, that would make it too obvious that he's not feeling well, and John might try to offer him some sort of pain reliever. Explaining why he doesn't want to take any medications would lead inevitably to admitting to several poor decisions over the last day or so, which John would of course swiftly convey to Mycroft (either purposefully or through his body language, idiot can't ever seem to lie properly) and then everything would just go right to hell.

So instead he winces away from the light as subtly as he can, edges into the kitchen; but then he realises he can't make tea because that has caffeine, and getting a glass of juice or water sounds like too much work for too little payoff. He settles for simply standing and glaring at the tile pattern by the sink. Not symmetrical. Abruptly he finds himself infuriated by the sight. Honestly, how fucking hard is it to lay tiles in a symmetrical pattern? Who the hell built this place, and were they blind or just stupid?

"You feeling alright?" John asks from the sitting room. Sherlock glances over with a scowl, then quickly turns back towards the sink as the reflection of sunlight off the mirror over the fireplace shoots a bolt of agony through his skull.

"Fine," he bites out. Clenches his fists at his side, makes a concerted effort to force the stormy glower off his face before he turns back around. Calm down, relax... he's perfectly alright, it's just a headache, nothing more. He can deal with this. He's fine.

"You look like you've got migraine or something." John's lowered his paper now, regarding Sherlock with a concerned expression. Sherlock can't stop the acid glare that steals over his features.

Bloody John and his bloody concern - it's not like the man actually cares. No, he's just following his usual role of the responsible doctor, diagnosing conditions, providing assistance; he'd do the same for any random stranger and the commonality strips the gesture of whatever meaning it might have held. Even more so when Sherlock knows full well the man would rescind all sympathy within seconds if he were to tell him what's really going on.

That's how it always goes, after all - everyone's full of comfort and support until they finally figure it out. Then the platitudes drop to steely disapproval, exasperated reprimands and trite, repetitive lectures. As if he's a child caught red-handed with a bag of sweets - always comes down to things like dangers and health risks, pathetic warnings that lose all meaning because for fuck's sake he bloody knows already. He understands the repercussions far better than John or Mycroft or Lestrade do, in fact, as he's actually been through them.

They haven't; he knows they haven't. Lestrade might perhaps have some inkling thanks to the cigarettes, but John? Mycroft? No, god, not in a million years. Tell me, John, exactly how many times have you overdosed? What's the worst thing you've ever been willing to do for half a gram of white powder? Do you have any idea what it's like to realise you're slowly killing yourself, only to find that you just don't care?

No. John doesn't have any concept. None of them do. And because of that they don't seem to be able to comprehend that appealing to a sense of self-preservation doesn't bloody work when no such instinct exists.

And then, of course, they'll all just move on to attempting to convince him of his own illusory fortitude. How could you throw away all that progress? You were doing well, you've been clean for years!

And no, he always feels like yelling, no he fucking hasn't been. No one ever seems to realise just how many nicotine patches he uses - how he hasn't gone a single day without one in ages. But just because it's legal they somehow assume it's different. It's not. There's less of a rush and the high isn't anywhere near as energetically euphoric but it's still a bloody stimulant, still affects his brain in exactly the same way as cocaine does.

And why, why on fucking earth is he allowed to indulge in one chemical addiction without comment while the other gets him locked up in a clinic at the merest hint of relapse? Societal double-standards, fuelled by politics and fearmongering rather than actual facts. And they all wonder why he disparages the human race as a load of brainless morons.

John's still looking at him, raising his eyebrows in a questioning manner and Sherlock realises he's been glaring wordlessly at the other man for a good two minutes now. He breaks the stare with a quick shake of his head (poor idea, headache exacerbated by the movement) and stalks off toward the sofa.

"I haven't got migraine," he asserts irritably, then flops down on the worn cushions and curls up with his back to his flatmate. Returning to his bedroom would probably be the more sensible option if he wants to avoid John asking questions... but he's just remembered about the morphine tablets hidden in the lining of the mattress, the marijuana tincture in his closet, extra nicotine patches on the bedside table, half-empty packet of cigs in the pocket of one of his old coats. No. No no no, his room is a veritable sea of hidden drugs and no matter what he's promised himself for the moment he knows his willpower won't hold out if salvation is near enough at hand. Better to stay near John - the doctor will no doubt continue to pester him, but that's a fair tradeoff for the benefit of keeping on-track with this forced bout of sobriety.

John doesn't try to interrogate him though. Mercifully he just lets the subject drop, goes back to his paper and reads quietly while Sherlock lies on the couch and scowls at the cushions like they're somehow personally responsible for the hell he's trapped himself in.

Presently the relative silence of the flat is shattered by the shrill chiming tones of Sherlock's message alert, and he shoves his face into the fabric of the sofa with a groan. Fucking hell, of all the bloody times to get a case... for a moment he allows himself to hope it's just some random social text, but of course it isn't. Nobody ever contacts him unless they want something investigated.

Sure enough when he finally gathers enough energy to roll over and snatch his phone off the coffee table it's to find a message from Lestrade; 'Three women dead, all missing their two front teeth.'

He very nearly texts back with something like 'good for them', or even just a simple 'leave me alone', but resists the urge. Lestrade's expecting him to jump at the prospect of a new puzzle - behaving any differently will only rouse suspicion and lead to questions. Questions which, quite frankly, he doesn't feel up to fielding right now.

He huffs a short sigh and reluctantly replies with the anticipated response. 'Suspects? - SH'

'None.'

Another sigh - god he really doesn't want to bother with this right now - but he nonetheless hauls himself into a sitting position. Best to just go and get it over with. Probably something pointless and stupid anyway.

"New case?" John asks from across the room, and Sherlock nearly has a bloody heart attack because he'd somehow forgotten the other man was there.

He forces himself not to startle, manages to mask the slight unavoidable twitch of surprise within the movements of standing instead.

"Doubtful," he answers in as flippant a voice as he can muster while his heart's still in the process of slowing down. "Likely just a serial killer. Not interesting."

"You usually love serial killers," John points out with a slight frown. In lieu of replying Sherlock just grits his teeth and heads for his room to get dressed.

A quick shower and change of clothes later and he's back to looking less like a pathetic, washed-out junkie and more like a responsible member of society. It's all a ruse, though - he still feels like nothing so much as a shambling corpse, and his head hasn't stopped pounding in what seems like an eternity. But still, beyond the pain and discomfort is a vague sense of pride... he hasn't ingested any sort of drug in well over ten hours now.

It's a pitiful sort of victory, yes, but an accomplishment nonetheless. Proof, he thinks, that he's stronger than they give him credit for.

But as he goes to pick up his mobile from where he'd left it on the bedside table his hand brushes a stray nicotine patch, and the little burst of triumph quite abruptly vanishes.

Because what, honestly, is he hoping to achieve with all this? Proving he can do it? Why? Nobody will ever know, assuming he somehow manages to overcome temptation... and besides which even if someone were to figure it out it's not like anyone would care.

What if he were to walk down the hall right now, stride into the sitting room and announce to John that he's been entirely sober for ten whole hours? Even in his head it sounds idiotic. And John will raise an eyebrow in scepticism - perhaps offer a vaguely condescending congratulations in that tone of slight befuddlement he always uses when Sherlock's being strange. It won't even register in the doctor's mind as a struggle worth validating... because truthfully it isn't.

Ten hours. Not even half a day. The majority of which he spent sleeping, and the rest sulking about the flat scowling at couch cushions. That's not an accomplishment, that's just stupid.

And it's not going to get any better. Not for a long time. The headache might ebb within a day or so but in its place will be weeks and weeks and weeks of exhaustion, moodiness, irritability... he'll be even more of a hellish git than ever, and John will snap at him, tell him to get over himself, to quit whingeing. Mycroft might stop by at some point, deduce the root cause of his sibling's newest round of mental imbalance and offer some meaningless gesture of moral support... but it'll be nothing more than hollow words, because no matter what Mycroft may try to insist Sherlock still knows his brother sees him as a weak-willed idiot for having ever developed something so plebeian as a drug addiction in the first place.

Then after all of that, even if he succeeds... what exactly will he gain from it? After all there was a bloody reason he'd climbed willingly into this self-made grave to begin with. Because his brain is a trainwreck screaming along through a firestorm of racing neverending reams of knowledge, and the only way to escape from the looming sense of imminent insanity is to freeze it all in place through chemical means. That won't change just because he's decided he needs to prove some asinine point about willpower.

Nothing ever really changes, he should damn well know that by now. But somehow he still always seems to forget.

Below his hand, which had frozen hovering over the tabletop, his mobile chimes again. Lestrade, of course. More details about the case. He hesitates only a fraction of a second before lowering his hand to his phone.

A pause, then he shifts it slightly to the side... and picks up the nicotine patch instead.

It's meant to be placed on the forearm but he affixes it to the crook of his elbow, positions the little round disk just right so it completely covers the small collection of slowly-healing needle marks he's accumulated over the last few weeks.

There, all evidence of his lapse in judgement perfectly hidden. Now nobody will notice. Not even if he wanted them to.

He tugs down his sleeve, plucks up his mobile, and heads for the front door.

Somewhere out there is a case to solve.

... and that's all that really matters.