Disclaimer: I don't own anything here but the story. Everything else belongs to ACD, the BBC and other people who aren't me.

13/07/12 – Now editing! Sorry for any extra alerts going out. Not really any major plot changes going on, just a few details to fit in with S2 cannon and some formatting issues. BUT THERE IS AT LAST A NEW CHAPTER! Thanks for your patience, guys.

SHSHSHSHSHSH

But Who IS He?

Lestrade and co. get to know John a bit better. Set shortly after ASIP.

SHSHSHSHSHSH

Chapter 1: The Peacekeeper

Greg Lestrade was having one of those days. The kind when he got desperate enough to call in Sherlock Holmes, at the risk of his subordinate's resentment and, more often than not, his own sanity.

The crime scene was a dirty alley off a Soho backstreet, littered with rubbish and the stench of overfilled bins. The four storey buildings on either side made it feel like the bottom of a chasm; they'd had to break out the floodlights for illumination at ten thirty in the morning. Greg had to crane his neck uncomfortably to just to glimpse the narrow strip of heavy grey sky overhead.

The body wasn't a pretty sight in the overly harsh halogens, either. The overweight, balding middle aged man was naked, sprawled on his side in the mud between two overflowing dumpsters. Lestrade counted himself lucky that the gloom and filth were doing a sterling job at preserving the poor sod's modesty.

The smell alone is giving me a headache without having to look at that; and Sherlock's not even here yet. Although it could just as easily be Anderson and Donovan; judging from the frosty looks they're giving each other, they've split up. Again.

The claustrophobic confines of the alley weren't helping the recently separated couple; every time they had to pass near each other both looked determinedly in the opposite direction. Anderson had tripped over the litter twice already. The tension was enough to make the corpse uncomfortable; with Sherlock Holmes added to the mix, it was inevitable that there was going to be trouble.

Sherlock exchanged his usual insults with Sally before ducking eagerly under the police tape in that ridiculously dramatic coat, almost eclipsing the stockier man following him closely.

Hang on… Isn't that the doctor he brought along on the serial suicides case? Whatsisname… Watson, wasn't it? Blimey; I thought he'dve been scared off by now. I bloody would be, if I didn't need his help so much.

"Ah, Lestrade," he practically purred, ignoring Donovan's best glare with practised indifference as his companion shot her an apologetic grimace. "I do hope you have something interesting for us…"

"Us? Sherlock, I called you," Lestrade protested, exasperatedly. "That doesn't mean you can just invite random people to my crime scenes…"

The Consulting Detective stopped short, whirling to glare down at the hapless policeman with his unnaturally intense grey- blue eyes. Not for the first time, Lestrade wished the man wasn't quite so ridiculously tall.

"Doctor Watson is my colleague," he said fiercely. "He's here because I need him here. If you don't want our help, Detective Inspector Lestrade, DCI Gregson has been texting me about a case with distinct potential…"

The manipulative bastard… he knows I'll do whatever it takes to get one over on Gregson since he beat me to the last promotion. At least this Watson bloke seems vaguely normal… well, compared to Sherlock, anyway.

On second thoughts, Sherlock Holmes is probably not the best measure of normality.

"Oh… all right," he capitulated grudgingly. "But make sure he doesn't touch anything, will you?"

"I'm not five, Inspector; I'm not going to start mucking about with evidence," the doctor snapped back at him.

"See that you don't; or neither of you will be getting on another case any time soon," he warned, more in hope than expectation, as he led them to the dingy corner where the body had been found. "We've got a middle aged man, starkers, no ID, no obvious cause of death. Cleaner found him about an hour ago when she took the bins out from the dodgy nightclub at the other end of the alley. Said she only phoned us so she wouldn't have to trip over the body every day until they got emptied, and then her statement turned into a long and colourful rant about the council and how it's recycling policy is the root of all evil."

Didn't seem the least bit upset about the experience; having to separate paper from plastic got more reaction from her than a dead body. Either she's somehow related to Sherlock, which going by her Eastenders accent is highly unlikely, or this isn't the first corpse she's come across. Either way, she's definitely on the suspect list.

Greg sighed heavily, knowing exactly what he was letting himself in for. "I need whatever you can give me."

Sherlock stalked around the body with infinite care, eyes roving incessantly over every detail, from the victim's eyelids to the vaguest impressions in the mud. Sometimes Lestrade half-expected to see little green symbols scrolling across his pupils. The magnifier emerged from a pocket and the Consulting Detective flicked his coat tails fastidiously away from the filthy ground as he crouched to look closer, paying particular attention to the corpse's hands.

"Well?" Greg asked wearily as Sherlock straightened with his customary grace, knowing from long experience that his faint smirk meant he'd just worked out the man's life history and was about to be both insufferably smug and very insulting to everyone else in his immediate vicinity.

"Not a great deal to be learned from a body in this state," Sherlock informed him with excessive casualness. "I can only deduce that he was a long distance lorry driver who has been working abroad recently. Heavy drinker, probably has a criminal record considering the number of scars on his knuckles from all the fist fights he's been involved in. He gave up smoking approximately three months ago, separated from his wife within the last year and has lost a significant amount of weight in a short space of time."

The smile on the doctor's face was frankly admiring as Sherlock made an inviting gesture and he crouched down beside the body to examine it for himself, as deft and gentle as if the man were still alive.

Anderson, who'd been in a thoroughly foul mood already, snorted, loud and mocking, from behind them. "And his mother has a miniature poodle, I'm sure," he spat contemptuously.

Lestrade pinched the bridge of his nose as Sherlock's lips tightened with that special loathing he seemed to have for the forensics officer. Oh, God… I do not need this today…

But just as Sherlock opened his mouth to say something blistering, Watson interrupted.

"You sound a bit croaky, Anderson," he said pleasantly, with a touch of professional concern. "D'you want me to take a quick look, in case you're coming down with something?"

"No, I do not!" Anderson protested vehemently. "This is a crime scene, not a walk in clinic. And I'm fine, thank you very much."

"I'd get a second opinion on that if I were you; I can tell from here that your breathing's all wrong. There's a lot of flu about at the moment; and it's always best to diagnose it early. You can go and see your GP if you don't trust my opinion."

"Wrong? How can breathing be wrong? Are you even a real doctor?" He asked suspiciously.

"Of course he is," Sherlock informed him, his eyes sliding to John's with the appreciative sparkle he usually saved for the really clever murderers. "And I have it on excellent authority that he's very good."

Watson grinned back at what was clearly a private joke between them. Lestrade could only stare.

Sherlock… joking? Sharing a joke with someone else instead of just pointing out how stupid they are? Have I accidentally stepped into some strange alternate dimension or is this blasted headache just making me see things?

"All right, you lot; that's enough mucking about," he said sternly, sending a fierce glare at all three of them. "Let's hear it; how'd you work all that out?"

"Simple, Inspector; I observed," Sherlock replied with his usual condescension. "The right side of the face and the right forearm are significantly more heavily tanned than the left; which means he spends a lot of time driving with his arm sticking out of the window; you don't get that pattern any other way. Not possible that he could get that deep a tan in England at this time of year even if it were warm enough to wear a short sleeved shirt, so he's been driving abroad recently, and it must have been a fairly long drive to tan as darkly as that."

"That's ridiculous; for all you know, he could've hired a car on holiday…" Anderson sneered, but was immediately cut down.

"But if he had, the tan would have been more consistent across his body; no one goes on holiday and spends the whole time driving. You can clearly see the tan line above his right elbow and around the neck, but his shoulders, back, and legs are all pasty white; he hasn't been sunbathing. If he'd hired a foreign car the tan would also most likely have been heavier on the left arm, since more countries drive on the right side of the road and therefore the driver's seat is on the left. No, he drove a British vehicle abroad for a significant distance without taking any time to sun himself so driving is his profession, borne out by his less than athletic physique; lorry driver, obvious. Besides, he's an alcoholic going through a separation; he doesn't have the money to waste on holidays."

"And how'd you know that?"

"It's obvious, isn't it? Beer gut, excessive redness of the nose and cheeks where the capillaries have burst, slightly jaundiced skin tone where it isn't tanned; clear sign of a failing liver. Faint mark from a wedding ring on the left hand but it's been removed for a while because the pale skin underneath has almost darkened to match the rest of his complexion. So, separated but likely not divorced yet; it's usually a protracted process."

"And you can tell he's given up smoking because… what, he smells of nicotine chewing gum?" Lestrade asked sarcastically.

"No; I can tell from his fingernails."

"His fingernails?" The doctor asked curiously.

"It's surprising what one can learn from fingernails, John. They provide an excellent record of a person's recent activities. Look closely at the index finger of his right hand; you can see that the most recent growth of nail is clear, but the older nail above it is stained orange by cigarette smoke. The growth rate of finger and toe nails in a man of this age is about two centimetres per year, and the pale section is approximately five millimetres long; ergo, he gave up smoking around three months ago."

"That is astonishing, Sherlock," John told him, looking at the detective like he was the most incredible thing he'd ever seen. The consultant actually seemed to be basking in the praise.

"It's guesswork," Anderson snapped derisively. "He's nothing but a freak that uses random details and stupid theories to make up so-called evidence and then calls it science!"

"I do not make it up, Anderson; just because your minuscule excuse for a mind cannot grasp the concept of observation…"

"Sherlock, can you argue later?" Watson interrupted yet again, peering more closely at the man's chest. "I think I've got an idea on the cause of death."

"Only one? At least four have occurred to me."

"It was asphyxiation," Anderson sneered. "You only have to look at the cyanosis in his fingers, if you're not too busy studying his manicure..."

"I wasn't asking you, Anderson," Sherlock snapped. "You know I don't like you talking in my vicinity."

"Well, that makes two of us."

"Good, glad you understand at last. You can speak again when I've solved the case. John?"

"Well, I'm not really an expert in forensic pathology… but I don't think he suffocated."

Sherlock smiled. "Go on," he encouraged.

He looks almost… proud? What, is he trying to train up his new mate into another Consulting Detective? God help us… One is more than enough trouble.

"Well, the blue tinge to the nail beds does suggest oxygen deprivation, but there's not a mark on the face or neck; no haemorrhaging in the eyes, and the hyoid bone in his throat is intact and correctly located. Could have been drugs or poison, of course, but there's usually some sign of peristaltic reaction to ingesting toxins."

"Peri- what?" Lestrade asked. Of course it was too much to ask for a friend of Sherlock's to be able to hold a conversation about a body that I actually understood.

"The body's first reaction to poisoning is to empty the stomach. I can smell alcohol but no vomit on him, so unless someone decided to brush his teeth with Scotch post-mortem, this man probably didn't react to something he ate or drank."

"Very good, John," Sherlock praised, almost warmly. "What else?"

I don't think I've ever heard him congratulate someone else at a crime scene and mean it before. Blimey; he must really like this Watson character…

"I think there's a more long term cause for the cyanosis; did you notice this small surgical scar between the sixth and seventh ribs?"

"Of course."

"That's a typical location for a lung biopsy, and it's relatively fresh; eight, maybe ten weeks ago. Ex- smoker, heavy drinker, you said he'd lost a lot of weight rapidly… Lung cancer isn't unlikely."

Greg, currently on his fourth attempt to give up, shuddered at the thought.

"Plenty of lung cancer patients also experience heart problems, because the heart has to work harder to get enough oxygen to the body. Could've easily been a heart attack."

"Well done, Doctor Watson. That is indeed a plausible solution."

"Really?"

"Why so surprised, Doctor?" Sherlock drawled.

"I expected you to see a wrinkle on his left earlobe or something that proves he was bitten by an exotic spider. Heart attack's a bit dull for you."

"Very nearly everything is dull to me. And don't be an idiot, John; it's clearly far too cold out here for any kind of tropical arachnids. Even if it weren't, the swelling and inflammation of the puncture wound would be impossible for even Anderson to miss." He cast a nasty look at the fuming forensics expert. "Myocardial infarction will very likely prove to be the cause of death, although I suspect that it was chemically induced; most likely by an anticholinergic toxin, judging by the slight flush to the skin and the excessively dilated pupils. But the main interest is in the path the body took to get here."

"What d'you mean, the path?" Lestrade asked. "You think he decided to take a midnight stroll in his birthday suit and then keeled over?"

"No, of course not! Use your eyes; he didn't walk into this alley. Just look at his feet; there's mud all over his legs, ankles, the side of the foot, but not a trace on the soles. He was already dead when he was carried in; would have taken at least two people, he weighs, what, fifteen stone ten despite the weight loss. And look how the body is positioned; out of view of anyone until they're right on top of it. Notice these streaky dragging patterns in the dirt around him; there's still a few left despite your lot's blundering around the crime scene. How many bruises do you see on the body, John?"

"Err… next to nothing…"

"Exactly. And what's the easiest way to carry a corpse without bruising it?"

"Well, a stretcher, ideally, but that's not something everyone has lying around."

"But what they do have lying around is…" Sherlock practically skipped to the nearest reeking bin and tugged at the edge of a tarpaulin that had been shoved into the side.

"A tarp? You think they used the tarp to carry the body, like all the rolled up carpets you always see on telly?" Anderson asked incredulously.

"Criminals watch telly too," John commented, with a wry glance at his friend. "And if you haven't got a stretcher, good strong fabric's the next best thing. People aren't easy to carry."

"Well, you'd know, Doctor," Sherlock replied. "The challenge will be working out where he was carried from; and what he was poisoned with, for which unfortunately, we shall have to await the toxicology reports. If we are extremely lucky, they might even be correct."

"Our results are always correct, Freak!" Anderson protested. "You think you're so bloody clever; you try handling six cases at once and doing all the official paperwork that comes with them…"

"Certainly. All of them would be solved within twenty-four hours and leave me plenty of time to improve your lab with the fly larvae experiment John won't let me do at home."

"We've had this conversation, Sherlock. Baths are for bathing in, not for breeding maggots on human torsos."

Lestrade blinked. Did he really just say that in the same tone my mum used when I put frogspawn in her favourite vase as a kid?

"Only because you threatened to tell Mrs Hudson if I actually did it," the consultant replied, somewhat resentfully.

"'Course I bloody would; I draw the line at living in a flat that smells of rotting flesh, no matter how cheap the rent is."

"You two... live together?" Lestrade managed. Sherlock having a friend is odd enough; the idea of Sherlock having a boyfriend boggles the mind.

John rolled his eyes in exasperation. "I'm Sherlock's flatmate," he said with emphasis. "Just his flatmate."

"Are you serious?" Anderson interrupted with incredulous disgust. "You really live with that freak? Better get out now before he starts experimenting on your torso; he's the type to keep random body parts from his victims to experiment on."

"Don't be ridiculous, Anderson; I occasionally use the leftover teaching materials from Bart's for experimental purposes," Sherlock informed him irritably; and then his eyes took on a distinctly calculating expression. "Have you ever considered donating your body to medical science, by any chance?"

Anderson's eyes widened. "Not any bloody more, Freak!"

"Pity. Dissecting your brain could greatly expand science's understanding of idiots."

"Lestrade, you heard what he just said! How can you possibly allow this psychopath to threaten a police officer on my own bloody crime scene and do nothing about it?"

"It wasn't a threat, Anderson; that was what we mentally functional people like to call an 'idea'." Sherlock sneered. "I realise that this may be a foreign concept, but do try to keep up. And it's not as if you need it. Tell me, is it physically possible for you to use that scrap of grey matter between your ears or is it just there to think up new excuses for your wife while you sneak off to see Sally? Although it seems she's finally had enough of you too." He raised his voice a little. "Congratulations on an excellent decision, Sergeant Donovan."

"Piss off, Freak," she called back from the tape, having made sure to keep as far away from Anderson as she could without actually leaving the crime scene.

"With pleasure. Come on, John; this will be twice as difficult now the police have blundered over all the evidence."

"We do not blunder!" Anderson shouted after him, as the lanky consultant strode away, eyes fixated on every subtlest undulation of the sludgy black mud that coated the alley floor.

John, however, hesitated beside the livid man.

"Look, Anderson; the whole world knows you can't stand Sherlock," he said, matter of fact but not unkind. "It also knows there's nothing you can do to stop him turning up at crime scenes. Is it really such a leap to think about staying out of his way, or at least shutting up and letting him get on with it so you can get rid of him sooner?"

Lestrade's jaw dropped. Is it really possible that Sherlock's flatmate is trying to be nice to Anderson? Because if Watson's going to try and keep the peace between them, I might as well get him packed off to the nuthouse now…

SHSHSHSHSH

This story started out as a one- shot, mutated into a series of them and now I think it's going to be an actual case fic. Updates will probably be a bit slow until I've worked out what exactly is going to happen; plus deductions are frighteningly intricate things that take at least three draughts to get right. Hope mine read as believable; and if not, constructive criticism is always welcome.