Author's Note: It should be known that I am neither a doctor nor am I a resident of the UK. Therefore all 'facts' relating to the use of cocaine, medical injuries, English slang, or the London area are based only on my, admittedly, shoddy research and are seriously up for debate. I apologize in advance.

"John, you might want to shut up now."

"Yeah but come on… no…"

"What?"

"… You?"

"Shut up!"

- BBC Sherlock 'A Study In Pink'

(1) The Discussion

It was 3:17 am and John was only now finishing his dinner. In the past 24 hours he'd been to his first crime scene, met the man responsible for the continuation of the British government, helped pinpoint the location of a murderer, and then subsequently shot him. The evening had then culminated in a selection of (admittedly) delicious Chinese take out and a portrayal of Sherlock's skills in predicting fortune cookies. John still didn't understand how he did it. Sherlock had gone into full lecture mode trying to explain, sprouting statistics and snidely commenting on man's need to hear sentimental and uplifting bullshit. God forbid the cookie companies print something more plausible than everywhere you choose to go, friendly faces will greet you, especially when one was living in a city like London… blah blah blah. John decided to decode that lecture when he'd had more sleep.

Allowing Sherlock's voice to wash over him, John began thinking back over the day's events. He really should be writing them down. He planned to publish the case on his blog at a later date and it would be best to record the events while they were fresh in his mind. That however, would involve standing up, something he was under no circumstances ready to do.

So instead he simply sat, listening to Sherlock bitch about everything under the sun and mentally categorizing his adventure. He'd start with meeting Sherlock and then move straight into the murder. Perhaps he'd include a little humor, like Anderson's ridiculous attempts to be helpful (honestly, who went around writing 'revenge' in German?). He'd of course recount the thrilling taxi chase and perhaps another lighthearted scene would follow it. 'The Drugs Bust' he silently titled it, in which Sherlock and Lestrade engaged in a battle of wills, wits, and words and the reader discovered that Sherlock wasn't so perfect after all—

Hold up. John opened his eyes, mentally putting his notes away in a drawer for later. That was a good point. He'd reached the moment in his story in which the reader came to understand that the oh-so-flawless protagonist was anything but. In Sherlock's case, he'd more than hinted at the fact that he was a druggie. However, in real life he'd sidestepped John's questions and, quite frankly, they'd had more important things to worry about at the time.

They certainly didn't have anything to do now though.

"So…" he began.

Sherlock quirked an eyebrow.

"Soooo…" He really had no idea how to start this conversation. Then again, he'd already questioned the man about his sexual preferences. Hell, he'd killed for this man. Surely a bit of drug discussion between friends wasn't that big a deal, and he already knew about the nicotine patches.

"So where are they then?" There, straight and to the point.

"Where are what?"

"The drugs."

Well, Sherlock was looking more amused than offended. That had to be a good sign.

"Do you want to try some?"
"What? No!" John leaned forward and snatched a dumpling, stuffing it into his mouth. It was stone cold but he swallowed it anyway, smothering a grimace. "Why do you think I'd want to try your drugs?"

"You're asking where they're located. I thought perhaps you were interested."

"No. No, no, no. Just… no. Look, I'm only wondering because Lestrade obviously believed you had something here and you all but admitted to it and I was just curious, okay? Besides, it's not like I care or anything. Everything's—"

"Fine?" Sherlock smirked, a quick pull of the lips that said more than most men's entire faces. "Yes John, I'm aware that it's fine." He slanted a look at him across the table and absently began swirling his chopsticks. "Though honestly, I was expecting a bit more of a fight. I'm surprised you're advocating this. You are a doctor after all."

"I'm not!" He flushed. "Advocating that is. But well…" John leaned back, finally relaxing into his seat. "You're going to do what you're going to do right? As your doctor I certainly can't approve of your habits but as your flatmate and friend…" He shrugged. "Who am I to tell you how to live your life?"

"How very philosophical." The words were flippant but John noticed a strange look on Sherlock's face, something he couldn't quite identify. He'd almost seemed uncomfortable when he'd used the word 'friend'…

In a second though the moment was gone and Sherlock was striding towards the fridge. John had a strange thought – do people keep their drugs in the fridge nowadays? – but Sherlock only pulled out a carton of milk and downed it in one go.

"So…" He felt like they'd been here before. "Where are they?"

That smirk again. "Where is what John? You must learn to be more specific."

"The drugs!"

"Ah yes. The drugs." Sherlock chucked the empty milk carton. It landed somewhere behind the microwave. "Like I'm going to tell you."

"What? Why not?"

"Cause John, you just might be tempted, and I for one won't be responsible for the deprecation of London's Golden Boy."

"Oh please. 'Golden Boy?'"

"But of course." Sherlock waved his arm dramatically. "John the decorated soldier, willing to fight for queen and country. John the doctor, dedicated to fixing all aches and ills. John the flatmate, willing – or perhaps merely stupid enough – to live with the world's only consulting detective. Really John, you're quite the long suffering martyr."

John watched as Sherlock reclaimed his seat, mentally noting how the conclusion of the case seemed to have put him in a good mood. If he were ever going to find out anything about his new companion's drug habits, now would be the time.

"Well if you won't tell me wherethey are… though I'm fairly sure I could find them myself—" A strangled snort at that. "I could! It's not as if we're living in some monstrous palace. This flat can only have so many hiding places."

Sherlock's expression told him exactly what he thought of that statement. Perhaps it was best to move on.

"If you won't tell me where they are, will you at least tell me what they are?" Silence. "Oh come on! A few hours ago I announced to half of Scotland Yard that I'm your doctor and as your doctor I think I should be aware of what kind of poison you're putting in your system."

It looked for a moment like Sherlock would still refuse to answer him, but finally he gave a casual shrug as if didn't give a damn what this John Watson thought of him. And the thing was, he probably didn't. "You already know that I'm trying to quit smoking and the nicotine patches help me think. Other than that it's mostly cocaine, though I have been known to use morphine on occasion."

John didn't know what he expected, but he hadn't counted on hearing that. He wasn't a fool by any means, God knows his army buddies had been on enough 'prescriptions' to fill a pharmacy, but even he wasn't used to someone admitting they used coke and morphine like other kids popped candy. Alcohol – fine (he was certainly used to it with Harry). Nicotine patches – yeah okay. But cocaine? Morphine? That… that wasn't okay. The doctor inside him, the healer, protested most violently.

"Well then, if you've satisfied your curiosity I'll be in my room." John had the distinct impression that he'd say something stupid if he opened his mouth. Best to just nod and say good night. And yet…

"Sherlock!" He stopped on the stairs, giving John a look he'd seen random mothers use on cute but annoyingly persistent children. "You're not going to… well, what I mean is, you can't…" He stopped. Yep, he knew he shouldn't have opened his mouth. Instead of being offended though Sherlock laughed. It was the first time he'd truly heard his new roommate laugh, and it was a wonderful, deep sound. So thick John felt he could breathe it in.

"No John. Trust me, you'll know when I'm high."

(2) The Confrontation

Apparently Sherlock – god forbid – had been wrong. John couldn't tell when he was high and it took him nearly a year to admit he'd been in denial.

Once it was clear that Sherlock was using – not addicted, but certainly using – he couldn't help but run through the numerous lists of signs, symptoms, and long term effects he'd learned back in Intro Psych and later solidified in med school. These lists scrolled constantly across his vision, appearing in the same order they'd originally been presented in Dr. Sharp's power points and the hundreds of laminated note cards that currently resided under his bed (he'd never had the heart to throw them out. No doubt Sherlock knew of their existence and was merely waiting for the perfect opportunity to use them as blackmail; his punishment for being 'overly sentimental.')

However, despite the added stress to his already overtaxed mind, John acknowledged these lists as just another part of being a doctor. He could no more ignore his knowledge of the physical and mental ramifications of cocaine than Sherlock could ignore the lure of a blood trail. They simply became another part of his everyday routine: get up, shower, dress, drink an abundance of tea (without milk, more likely than not), and review the standard signs and treatments for an overdose in case his flatmate – once again – decided to be an ass and do something fundamentally stupid.

He tried to be clinical about it, but even so there was one symptom that he'd given more than a fair bit of attention to. He could see it, floating in the air before him in the curvy scrawl of his own handwriting:

Friends and family of the patient may mark a distinct change in his/her personality, most notably an increase in risk-taking and violent behavior.

When he thought about it, it really made a lot of sense.

After all, Sherlock was the biggest adrenaline junkie John knew. Jumping from rooftops, starting uncontrolled fires, and then there was that wonderful time last winter when he got his tongue stuck on a crime scene's mailbox (he still insisted that taste was an exceptional tool for the consulting detective)… surely the cocaine at least contributed to these moments of (sometimes) humor and (more often) terror. Or, perhaps even more likely, the cocaine was the cause. John wasn't sure just how often Sherlock was using but with enough frequency the drug could certainly cause permanent damage to a patient's ability to assess the risks of any given situation. So by the time three months had passed John had convinced himself that the drug was mostly to blame for his flatmat's lack of self-preservation skills. No one could really be like Sherlock Holmes, not without some artificial help. Crazy, overly dramatic, semi-suicidal geniuses didn't exist in real life - at least not naturally. John was sure of it.

And then, a week ago, Sherlock jumped off the Tower Bridge and fell 143 feet into the Thames.

They'd been chasing a commonplace thief, merely another one of London's many men trying to earn some extra pounds for liquor, false love, and the like. However, this thief was notable in that he'd chosen the night of November 6th to pinch the copper gutters from an old lady's apartment. Sherlock, convinced these drains held the missing evidence he needed to solve a murder that had occurred down the block that same night, tracked the thief to the pedestrian crossing of Tower Bridge. And the thief, unprepared for the wrath his petty theft had invoked, panicked and tossed the scrap metal over the side.

Sherlock, being the genius he is, jumped in after it.

By all accounts the idiot should have been killed. Hell, he deserved to be killed (John was still contemplating taking a baseball bat to the side of the numpty's skull) but luckily he'd been more concerned with keeping the evidence in sight than with executing a perfect dive and had managed to land feet first.

The impact shattered his left leg and managed to break more than a few bones in his right foot. The fall had also cracked two ribs and, more dangerously, knocked Sherlock unconscious. Had a boat not been passing at the time and had it not contained a heroic passenger willing to dive in after him, John's idiot flatmate would have drowned.

The fallout, when it came two days after the surgery on Sherlock's leg, was spectacular. John had filled the hospital room with everything he could think of to keep his friend entertained. Electronics, manuscripts, boxes of god-only-knows-what he'd found stuffed behind the couch. He'd even managed to slip the skull in under the nurses' watchful eyes (he had a sneaking suspicion Mycroft was responsible for the hospital's sudden lack of concern with patient hygiene.) John knew well the monotony of hospital stays so he could only imagine how hard it must be for someone like Sherlock. The complete and unrelenting boredom. So he tried to be a good roommate, a good friend, and help the idiot through this. After all, he was just ecstatic that Sherlock had something to complain about. He was alive.

But after he came out of surgery – after John knew, comprehensively knew – that he'd be okay, something in him snapped. He'd walked in, skull hidden snugly under his coat, to find Sherlock sitting up, a furious look in his eyes, and Lestrade standing over him.

"Honestly you lot are completely useless! We had one major source of evidence – one! – which I had in my hands, and you imbeciles couldn't be bothered to take the thirty seconds required to grab it and pull it into a boat!"

"Sherlock, we were a bit more concerned with fishing you out of the Thames!"

"Exactly. You were concerned. You let your emotions override your judgment and now this entire case is jeopardized. This is exactly why you are such a failure as a detective-"

From his vantage point John could see Lestrade's face as he turned away, hiding the involuntary flinch his friend's words had caused.

"Sherlock, I understand where you're coming from, really, but even you have to realize your life is more important than some measly piece of evidence. You should have never been in that river in the first place."

John thought perhaps the quite conviction in Lestrade's voice would finally get through but instead of looking contrite Sherlock crossed his arms violently, yanking his IV and upsetting a tray across the bed. The defensive posture made him look like a petulant four year old, and his next words only furthered the image.

"Whatever. I would have done it again if given the chance."

"What do you mean you'd do it again?"

It was fairly obvious by this point that neither had realized John was in the room. Lestrade gave a start at his whisper – somehow more frightening than if he had shouted – and Sherlock seemed to be making an effort to look slightly less bored.

"John. Wonderful of you to finally show up. Did you bring my skull? He's certainly a better conversationalist than you lot."

John paused. Sherlock must not have heard him. Hell, he could barely hear himself over the rushing in his ears. Although, even with the pounding in his head and the waves of heat creeping up his neck, he was dimly aware of Lestrade mumbling something about paperwork and beating a hasty retreat out the door. But Sherlock was still sitting there, acting like he hadn't just casually stated he would again risk death and serious bodily harm for the sake of some scrap metal. Perhaps it was best to repeat the question.

"What. Do you mean. You would do it. Again?

Well, now he had his attention. Sherlock actually bothered to make eye contact that time.

"Ah, I see. Yes, here we go. I've upset you haven't I? Listen John, you've got to get over this ridiculous obsession with my well being. I am fine. Truly, I thought you were a decent enough doctor to realize when people actually need your help. Me? I'm not one of them. So play nursemaid with someone else, okay? Now, pass me my phone."

At some point during that tirade the heat creeping up his neck began to creep into his vision as well and that was when the thing inside him broke loose. John honestly couldn't remember much about the subsequent fight. He was informed later by both Mycroft and Lestrade that there had been a lot of yelling on both sides – you're the most inconsiderate bastard I've ever met this and I need an assistant not another goddamn mother that. John had never been happier that Mycroft held a crazy amount of influence, as he was able to clear the hallway both quickly and efficiently, saving what was left of their dignity. More insults were tossed out, two glasses were shattered, and when things got truly out of hand Sherlock finally grabbed the damn phone himself and chucked it at John's head.

What John did remember was the very end of the fight when, finally losing whatever self control he'd previously retained, he'd screamed himself hoarse about the cocaine. How Sherlock was a fool to rely on artificial stimulants when he had people – real, live, human, people trying to help him. How he was a thoughtless prat to endanger John with his drug abuse as well – what did he think was going to happen if someone other than Lestrade caught them with coke in their apartment? Finally, he raved for ages about what the drug was doing to his mind. How it was twisting his perceptions and giving him the false impression that he was invincible. How if the actual drug didn't kill him, the exploits it encouraged him to engage in would.

By the time John was done his throat was raw, the skull had fallen to the floor, and he had a sizable lump on his head from Sherlock's phone. He collapsed onto the bed (carefully of course, even now he didn't want to cause his friend undue pain) and waited for Sherlock to make the next move. However, he said nothing. Thinking back, John realized Sherlock been silent since he started in about the cocaine. Could he possibly have shocked the great consulting detective into silence?

Well no. Sherlock was silent but he certainly wasn't shocked. He leaned back against the pillows, folded his hands under his chin, and gave John what he thought of as his you-poor-man-how-do-you-stand-not-being-me look. The one he generally reserved for Anderson on his good days and Lestrade on his bad.

"John…" He leaned forward, fixing his flatemate with a piercing stare. John felt a bit like the frog Sherlock had been dissecting two weeks before. "What are you talking about?"

"The… cocaine." John blinked. He felt more and more the amphibian.

"Yes John the cocaine. That dreaded, evil cocaine. The cocaine that I am not currently on."

"But you were." He felt obliged to point out.
"No."

"No?"

"No. I haven't used any since we went through that terrible lull in crime weeks ago. Honestly, the criminal class is losing its touch."

John simply sat there, not quite comprehending what he'd been told.

"You mean," he finally said "you weren't high when you jumped off that bridge?"

Aaaaand there was the smirk. "No John. I was not high. Honestly, you should know by now that I never use while on a case. There's simply no need."

John blinked. Again.

"I'm glad we've got that worked out. Now, are we going to scream at each other some more or are you finally going to do your duty as a friend and entertain me?"

So that was it then. All it took was one near death experience and the subsequent fallout to completely shatter John's established worldview. The cocaine had not caused him to jump from the bridge. The cocaine had never caused any of the ridiculous stunts his flatmate was inspired to pull. Looking back on it now he'd clearly been in denial and, like always, in one fell swoop the detective had managed to tear him from his cocoon of naivety and leave him standing bewildered among the ruins. All of it – from the eccentric lifestyle to his suicidal work ethic - had simply been the man. Sherlock was in reality exactly like Sherlock

Imagine that.

(3) The Deduction

So by the time he'd been living a year with Sherlock Holmes John Watson knew both what he was using and when he was using it (though as Sherlock had predicted he could not find where these drugs were located, and not from lack of trying.) The only question that truly remained – other than why his idiot friend would use in the first place – was exactly what kind of cocaine he indulged himself in.

He'd tried asking of course, but hadn't met with much luck. After their fight to end all fights Sherlock had closed up like a clam about his drug habits. He'd tried to play the doctor card again, saying that the way in which Sherlock administered the drug would affect what kinds of symptoms he'd be experiencing. Or, god forbid, the kind of overdose he may some day have.

It didn't make any difference though. If Sherlock was ever willing to talk about it, now wasn't the time.

Personally, John was inclined to imagine Sherlock favoring injection. The other main forms of administration had been rejected through careful process of elimination: Ingestion simply took too long, and he couldn't imagine Sherlock voluntarily eating any more than he had to. The man was positively phobic about anything resembling normalcy, and that apparently included dining on a regular basis. Inhalation could have been an option but John was inclined to believe his roommate when he said he wanted to quit smoking and he gave him the benefit of the doubt and assumed that meant all types of smoke. Snorting was a possibility, although it seemed a little too inelegant for the great Sherlock Holmes. It couldn't be completely ruled out however. So, that aside, John was willing to use his own meager skills and deduce that Sherlock injected.

He couldn't say he was terribly pleased to be proven right though.

Three months after the bridge fiasco Sherlock was healed and back to his usual self. The universe seemed to be celebrating his return by dumping a particularly gruesome murder in their laps. Hugh Mount, a 37-year-old baker had been found dead inside his bakery on the morning of February 17th. His young assistant, 14 year old Mathew Hay had come in early, as usual, to start the bread. Upon opening the door he found his employer lying in the display case with his throat split wide open. Upon closer inspection it was also found that the blood from the wound had been collected and used to ice the cakes made the previous day. There were three of them in all, laid out neatly upon the counter over the body, each glistening a dull red. The two small cakes were bare but the largest, centered in the middle bore the message: Happy Birthday Hugh.

It didn't take a consulting detective to realize this murder had been personal.

However, there wasn't much else to go on. Even Sherlock admitted that their assassin had been surprisingly careful in executing such a messy job. That alone allowed him to deduce that the murderer had a fair knowledge of the bakery's layout and baking in general (the cakes had been iced unusually well considering said icing was blood). The murderer was therefore someone who knew the victim well, had a keen understanding of his trade, and was most likely in peak physical health (as Hugh was not a small man by any means and it would have taken quite a bit of strength to get him into that case.)

"Other than those few points… you'll just have to wait." Sherlock said.

"Wait!" cried Lestrade. "What the hell do you mean wait?"

"For the next murder."

John perked his ears up at that. "Sherlock… you mean you think this person will kill again?"

"Of course. Isn't it obvious?"

John would swear he asked that each time just to get a reaction. Sighing, he decided to play along.

"No Sherlock, it's not bloody obvious. Why will he kill again?"

"Ah ah ah John, making assumptions are we? We don't know the killer is a 'he.' BUT we do know that he or she will kill again because of the cakes!"

"… The cakes?" said Lestrade.

"Yes the cakes! Good god you are a vacant lot aren't you… look at them! Three cakes laid out and iced in blood but there are four more in the fridge. Why didn't the killer ice those too?"

"Maybe because he… or she, didn't have time?" John ventured.

"No, no, no look at his clothes. Look at his hair! Carefully parted and smoothed with gel. Tucked in, wrinkle free shirt. Even the buckle on his belt has been polished! Whoever did this spent a great deal of time arranging his body after death. The killer wanted him to look perfect. If our murderer had enough time to do all this than he or she most certainly had the time to ice a few extra cakes."

"So the killer didn't want to then?" asked Lestrade.

"Brilliant deduction inspector, yes. These three cakes were chosen deliberately. Five of the seven that were made the day before vary in size but these two on the ends are the only two that are exactly the same. No, this was careful. This was planned. One cake addressed to the victim, two identical cakes left blank. There's going to be two more murders and I can't wait to see what comes next!"

Watching his friend practically skip across the crime scene John was tempted to remind him that a person was lying dead and he'd just expressed joy that two more would soon follow. But then he realized the futility of such an effort and just let Sherlock have his fun.

As they were walking out the door however, Sherlock suddenly stopped and drew in a deep breath. After a moment he turned towards Anderson who was bagging the murder weapon, a large serrated knife. Without any warning Sherlock thrust his face forward and gave an exaggerated sniff.

"Out of my face, freak!" Anderson reared back. "What the hell is wrong with you?"
"Oh please. Don't flatter yourself." Sherlock straightened up and cast a look of disdain towards the Scotland Yarder. "I wasn't smelling youI was smelling the knife."

"Why…?" Asked Lestrade.

"No reason really. Don't worry yourself over it Lestrade. Come along John! We have witnesses to see!"

They spent the rest of the day speaking more extensively with Mathew Hay as well as Hugh's other employees. They learned from them that Hugh had been a wonderful if slightly boisterous man and that they had no idea who would want to do this to him. The only lead they managed to obtain came in the form of a passing comment from Hugh's head pastry chef, a timid girl name Janice Reese. She informed them that Hugh currently lived with his two daughters, Laura and Sarah Mount.

John would swear to this day that Sherlock actually squealed with joy when Janice told them the girls were identical twins.

"The cakes John, the cakes! Identical cakes for identical girls! They're the next victims – come on – we've got to find them!"

They never did get the chance to meet Hugh's little girls however. The twelve-year-old twins were found dead in a local park two days later, propped up together under a large yew tree. Autopsy reports showed that both girls had been administered large amounts of helium and had eventually suffocated. John wasn't an expert in poisoning like Sherlock, but he could at least hope that the girls had died quietly and peacefully.

As if reading his mind Sherlock nodded. "Completely different MO. The baker's throat was hacked open but the cut was shallow. She wanted him to bleed out slowly. Wanted to watch him suffer. But the girls… she wanted them to pass as painlessly as possible."

"She?" John asked.

Sherlock nodded again and moved over towards the bodies. Bending down he put his head between the girls and sniffed. For the third time he nodded and without another word walked off, hailing a cab.

"Sherlock!" Catching up John slid into the seat and grabbed his arm. "That's it? You're just going to… to smell them? Where are all the grand deductions?"

He gave a faint smile at that but it quickly faded. "No need John. It was the wife."

"The wife? What wife?"

"Exactly. Don't you think it strange for a middle-aged man to be living alone with two young girls?"

"I figured the mother had either died or they'd gotten a divorce."

"Divorce." Sherlock said. "And a nasty one at that. No doubt he wasn't nearly as loving and accepting as his employees made him out to be. She was probably already a tad unstable from a rough childhood. He probably spent a good seven or eight years making her feel worse by commenting constantly on her condition. How can I be seen in public with you, do you honestly expect me to sleep in the same bed as you, things like that. Pressure builds up, she demands a divorce, but by that time she's enough of a mess that any court is going to deem her unfit for custody of two kids. Hugh takes the girls, wife finally snaps, kills him in the most gruesome way she can imagine and then lets her girls down easy. No doubt she's hauled up in a hotel somewhere having blown her own brains out. She could care less about Hugh but killing the girls would have overwhelmed her. You could sense the guilt in the cakes John. She'd left the two out hoping that someone – someone like me – would realize that she meant to kill again and stop her. But—" He shrugged. "We were too late."

John paused a moment, taking that all in. "Wait. I don't understand. What made her unstable? What condition are you talking about? Schizophrenia or something?"

"Nothing psychological John."

He waited, and after a few more moments Sherlock sad:

"Trimethylaminuria."

As a doctor John clinically went over what he knew of the disorder. As a fellow human being he winced.

Sherlock saw the reaction and agreed. "Yes John. Quite a rare disorder in which the body is not able to properly break down trimethylamine. Really, it wouldn't be such a big deal except for the fact that society is very strict about what is and is not okay and strong body odor has always been filed under not okay. Trimethylaminuria is known to cause a distinct smell in the patient's sweat, breath, and urine. I have heard it described as similar to rotting fish."

"Ugh. Poor girl. You're right, no doubt she went through hell as a kid and things couldn't have gotten any easier as an adult. But do you really think some comments on body odor could have driven her to murder?"

Sherlock slanted a look his way. "Of course John. Words are the most powerful weapon we possess. A mother tells her son he's stupid long enough and he starts doing poorly on tests. A kidnapper tells a victim they just want to help and that victim can develop Stockholm Syndrome. Tell a young woman that she's not attractive because of her condition, that she's not fit for certain jobs, that no one wants to be around her, that society deems her a monster… eventually she's going to act that roll out."

Slowly, John nodded. Yes, he could see how events might have played out. Shooting his own glance towards Sherlock he couldn't help but notice the carefully blank look on his face. The shrouded eyes. He too had experienced the negative impact of words. How many times had John heard Anderson and Sally yelling 'freak' across the room?

Next time, next time he'd do something about that.

Until then though he still had a few questions. "So then, how did you know the wife had Trimethylaminuria? That's not exactly a condition one naturally thinks of."

Sherlock tapped the side of his nose. "Nothing gets past this John. I immediately noticed the lingering smell on the knife she'd used to kill Mr. Mount. No doubt the anxiety of the situation caused her to produce a great deal of sweat and exacerbate her condition. The sweat adhered to the handle of the knife and left its distinct fishy odor. I smelled the same thing on the bodies of the girls." He was quite for a moment, then, "I imagine she must have held them for quite a long time for their clothes to smell so strongly."

They spent the rest of the ride back to Baker Street in silence, imagining a broken mother rocking her two dead girls.

It wasn't until later when it was dark and he'd fixed them both tea that something occurred to John. Holding the mugs in his hands he looked down at Sherlock, sprawled on the couch.

"Sherlock?" he said.

"What?"

"Scent was a pretty important part of this case, wouldn't you say?"

"I suppose. The set up of the murder led me to believe that the victim knew his killer quite well – hence we get the wife – but yes, it was the smell that allowed me to deduce her condition and ultimately her motive. Why?"

"So then you'd say for the consulting detective smell is a pretty important tool."

Sherlock looked up. "Certainly." His eyes narrowed "What are you getting at?"

"Just wanted to clear something up. My own little deduction." He handed Sherlock his tea and moved towards his chair, satisfied with his own logic.

Sherlock was having none of that though. With a bound he was sitting up and glaring at John.

"What do you mean your own deduction?"

"About your cocaine." John replied, picking up a discarded magazine.

"My cocaine?"

"Yes." He flipped through the pages randomly. "You wouldn't tell me how you administer it so I had to figure it out for myself."

A quick glance showed Sherlock developing the same amused expression he adopted whenever they discussed his drug habits. "And what, exactly, did you deduce John?"

He shrugged, trying to look like he didn't care. "You don't ingest it because you barely eat as it is and I can't imagine you ever willingly consuming more than you had to. I'm actually inclined to believe you when you say you're trying to quit smoking so I doubt you inhale it. The only real options left are snorting and injection. Snorting is a bit inelegant but it was a possibility. However," He finally looked fully at Sherlock, "you wouldn't sacrifice your sense of smell for a couple of highs. Not when, as this case has just shown, it's such an important tool."

Sherlock didn't look amused anymore. For a moment they each stared at one another. John trying to look like he didn't care that his friend was killing himself, Sherlock trying to look like he didn't care that John apparently didn't care.

It was John who finally broke the moment and returned to his magazine. "So," he said. "Injection it is."

Twenty minutes later, when their tea had gone cold, Sherlock finally stood up and walked to his room. As he passed his flatmate he rolled up the sleeve of his dressing gown, revealing the multiple puncture marks marring his skin. John had been right then, and all it had taken was four deaths to prove it.

Sherlock let his arm rest free for a moment and then continued on out the door, muttering on his way,

"Well done, John."

(4) The Changes

After that the cocaine, sadly, became a normal part of their lives. With a year and a half of living together having passed John could now easily spot the times when Sherlock was indulging. It would always be after a case, when the thrill of the chase died down and they were left with nothing more than what Sherlock referred to as the 'dull routine of existence.' Eventually Sherlock would stop complaining all together and that's when John knew the trouble had begun. Oh, Sherlock never shot up in front of him, but John knew what he was doing. The idiot would lounge on the couch, his head slightly nodding to music only he could hear, and he'd stay that way for days on end. Not eating, not sleeping, not truly alive. He'd remain in a near comatose existence until Lestrade called in the next case, and nothing John did could lift his spirits.

However, it was not nearly as bad as it could have been and John was grateful for small favors. Sherlock wasn't addicted and he obviously knew what he was doing in terms of when to dose and how much he needed. John was no longer terrified that he'd come home from the shopping and find his flatmate dead on the floor. As a doctor he still couldn't approve of this habit but he had to admit that Sherlock had it fairly well in hand. Or, at least, as well in hand as he could considering that he was playing with dangerous narcotics.

But for all his protests things really could be worse. The criminal class of London generally kept them more than busy enough for Sherlock to forget his artificial stimulants and John still ran through his lists of signs and symptoms in case his idiot friend ever needed help. He didn't like it, but he stood by what he had told Sherlock when they'd first moved in together: he wasn't going to tell him how to live his life.

And yet, in the month of August, John was glad he'd at least kept his vigilance up. Nothing dangerous had happened (well, nothing dangerous in relation to the cocaine) but Sherlock had begun acting strange – stranger than usual. It had started two months before at the start of the summer when he began wearing a pair of dark sunglasses wherever they went. At first John thought nothing much of it. After all, Sherlock had always had a preference for dramatic clothing. Long billowing jackets, fine silken scarves; if it was dark and impressive then Sherlock was inclined to wear it. John thought the sunglasses were simply the next logical (if slightly ridiculous) step in his wardrobe.

John was willing to indulge his flare for the dramatic but wearing the glasses inside as well as out was a bit much. By the end of July Sherlock insisted on keeping them on inside every building, while riding in every cab, under every archway, and inside each dark alley. John chalked it up to his friend's eccentric personality and told himself to move on.

He continued to ignore his instincts the first time he saw Sherlock wearing them inside their flat as well. After all, it wasn't the first time he'd worn inappropriate clothes for the environment. Half the time he'd lounge around their living room in his warm winter coat and ran outside in his dressing gown when changing his clothes simply took too much time. So when he came in to find Sherlock working at his computer, glasses still on, John ignored that as well - despite the nagging sensation that something was wrong.

He probably would have continued to ignore his friend's strange behavior if not for the bane of every workingman's existence: the common cold.

Sherlock, after chasing a subject through the pouring rain had come down with a nasty bug and even the hot summer weather hadn't helped clear it up. Through the combined efforts of John Watson, Mrs. Hudson, and the entirety of Scotland Yard, they'd finally convinced him to stay home and get some rest (no easy task that).

So here John was, standing outside Sherlock's bedroom door armed with tissues, Tylenol, and Mrs. Hudson's chicken noodle soup. Now if only he could get the bloody bastard to open the door.

"Sherlock! Let me in. You're never going to get better if you don't eat something!"

There was a muffled yell and then a loud thump. No doubt he'd thrown something at the door.

"Sherlock! You do realize you've taught me how to pick locks right? Open the door or I'll take the time to open it myself and then you'll be eating cold soup!"

In one violent motion the door was yanked open and there stood his flatmate. Frankly, he looked terrible. With his thin frame and already pale skin Sherlock made the common cold look like a case of Tuberculosis. However, what caught John's attention and made him forget all about the soup was the sunglasses perched on his nose.

"Sherlock…" How to put this delicately? "What the hell are you doing?"

A glare was his only response. Sherlock crawled back into bed and pulled the covers up high over his head. Honestly, the man acted like a four year old more often than not.

Depositing his tray on the bedside table John approached the shivering detective. From under the covers he could just see the beginnings of a mop of black hair, one ear, and the edge of his glasses.

"Seriously Sherlock. Why are you wearing a pair of sunglasses in bed?"

He heard something that sounded suspiciously like 'go away.'

"Is this some sort of experiment? You'd tell me if you'd done anything to your eyes right?"

Silence.

"Listen, if you've gone and fallen in love with some eyewear that's cool. Everyone's got their kinks."

More silence.

John heaved a dramatic sigh. "Oh fine… guess I'll just go ask Mycroft."

Suddenly the covers were ripped aside and Sherlock's head popped up. Ah, the joys of exploiting sibling rivalry.

"I am wearing them," he hissed, "because everything is so goddamn bright! Now go away." With that he was under the covers again, blocking out the world as only a Holmes could.

For a moment John was tempted to pull him back up and demand an explanation. What did he mean things were too bright? Yeah it was summer, it was bright outside – that's why they're called sunglasses – but inside? Slowly John turned to take in the room: the lights off, the window draped, an old towel stuffed against the threshold of the door to keep out the light. Everything screamed darkness and gloom to him. And yet…

Thinking back John took stock of all the times he'd seen Sherlock wearing his glasses. Outside, even with the added protection, he bowed his head and turned away from the sun. Inside he seemed to shrink against the hundreds of artificial lights that surrounded them. He remembered Sherlock's body language the other day, how he tried to work at his computer without really looking at it. Like the glare of the screen caused him pain.

John took all of that, added in the lack of cases they'd had this summer, and pronounced himself a fool.

"You know," he said gently "excessive use of cocaine can cause sever sensitivity to light."

He recalled all the hours Sherlock had spent locked in this room. At the time John had wondered what he'd been doing. Now he knew. But why did Sherlock suddenly feel the need to hide this from him?

Feeling daring he placed a hand on the bundled mass of misery that was his friend. He didn't respond but he didn't tense up either. Perhaps that counted for something.

Three days later, when Sherlock finally exited his room, he'd left the sunglasses behind and no amount of subtle hints or supportive words from John could make him put them on again.

(5) The Avoidance

John didn't know what had changed, but it was clear that Sherlock no longer held his cocaine in the same carefree light. He no longer lounged publically on the couch, but he didn't close himself off in his room again either. There were no more candid discussions of their drug habits late at night and under no circumstances did Sherlock again hint at his symptoms as he'd done with the sunglasses. If Sherlock was still using in between cases (and there was no reason why he'd stop) then John didn't know about it.

He'd originally thought that seeing Sherlock flaunt the cocaine was hard to take, but having him cover it up was even worse. If there was one thing John hated more than watching patients do themselves harm, it was watching them try to hide what was happening from their doctor. John couldn't very well come up with a cure for a disease he couldn't see.

Still, he tried. When it was clear that Sherlock would never again willingly ask for help, John tried to subtly treat the other symptoms himself. He wanted to say something significant to Sherlock without him realizing he was saying anything at all. He left cold cloths in the kitchen and soft blankets on the couch for an inability to regulate body temperature. More first aid supplies magically found their way into the flat, in the hopes that Sherlock was smart enough to keep his arm clean and sterilized. At one point John got desperate enough to be creative. He'd read in a medical journal a new article stating that drugs such as heroine and cocaine may in part be addictive because they stimulate our instinctual craving for salt. John still didn't believe that Sherlock was a slave to the drug and he was a healthy skeptic when it came to new research but really, what could it hurt? So pretzels, chips, and those disgusting TV dinners found their way into his cart while shopping.

John did everything he could think of and then did some more but Sherlock refused to acknowledge the subject. So they continued like that: the world's greatest detective and the detective's greatest friend, each ignoring what was so obviously coming between them.

(+1) The Acceptance

This routine of avoidance finally broke the night of December 19th, nearly two years after they'd first moved in together. John had returned to the flat after a pleasant night out drinking with Lestrade. Well, it had been pleasant until Sherlock's 'friend' from the Italian restaurant had wandered in and given him hell for 'cheating' on his 'boyfriend.' At that point John thought it best to just leave.

So he'd headed back to Baker Street, fully intending to watch crap telly and follow his beer with a pint of Cherry Garcia. That is, if Sherlock hadn't mixed poison into it. Again.

"Sherlock! I'm hungry. Please tell me it's safe to eat something in this flat." He came through the door fully expecting to find his friend puttering with his chemistry set or shooting holes in the walls.

Instead, Sherlock was sitting in his chair and shooting something entirely different.

"Um… hey." John said.

"Hey." Sherlock finished up and released the tunicate, flexing his arm in slow, lazy movements. Really, John didn't know the procedure for this situation. He'd seen Sherlock under the influence of the drug before but never actively using it, and the last few months they'd avoided this topic like the plague. Hell, they just didn't cover this kind of stuff in med school.

However, once it became clear that Sherlock was uncomfortable with him just standing there, John plopped down on the couch to face him.

"Why are you in my chair?" he asked.

"It smells like you." was the reply.

"Oooookay…" he was going to make sense of that at a later date. "Why this then?" he gestured towards the empty vile. "Why let me see it now?"

Listlessly Sherlock leaned back into the chair, watching him. They stayed that way long enough that John began to wonder if he wouldn't receive a response but then out of nowhere Sherlock shrugged.

"I thought that now you could handle it."

John's first reaction was to be offended. What did that mean? That he couldn't handle it before? But with a look from Sherlock he thought back to the night of their first discussion, how he'd thought he'd understood what was coming only to be floored by his new friend's nonchalant attitude. With a flush of embarrassment he remembered his tantrum in the hospital and later how he'd been obsessed with deducing how he administered the drug. Sherlock was right, before he couldn't handle it. But then… something had changed. Or rather, Sherlock's methods had changed.

"That was a test wasn't it?" John said. "Concealing the drug, hiding out in your room, refusing to even talk about it… you wanted to see how I'd react."

Sherlock nodded. "I suppose so, yes. You claimed you wanted me to – how did you put it? – 'live my own life,' but when I explained to you what my life entailed you weren't comfortable with that, despite your assurances. So, eventually I decided to see how you'd react if it looked like I'd done away with the cocaine. No more displays, no more obvious symptoms, no more discussions. But instead of being relieved you became more anxious. I gave you the option to ignore the problem and you didn't take it. If anything, you fought for me to be honest about what you now accepted to be a part of me." Sherlock's smile cracked into a full-fledged grin. "That was… good John. Very good. You accepted the situation and attempted to deal with it accordingly. You reacted like true soldier."

John snorted and flashed a grin of his own. "Yeah well… just as long as you don't OD on me. I've got enough work as your doctor already thank you very much."

Sherlock waved a hand as if to say his worries were groundless and oddly enough John was reassured. Sherlock was right, he hadn't been okay with this before but he was now. He supposed he had to be.

"There is one other thing though…" John began mischievously. "Cocaine Sherlock? Really? It's good but come on, personal connections with the criminal underworld, a brother who could get you anything or everything at will… and you choose cocaine? Nothing wrong with it of course, it is fairly high class but… well… forgive me, but it still seems a bit plebeian for your tastes. Frankly I expected better from you."

Sherlock's eyes narrowed, but the grin was peaking through.

Yep. They were fine.