A/N: I wasn't going to continue this, but people seemed to want a conclusion, so maybe a few more mini chapters? Let me know! Feedback on their interactions, etc.
Disclaimer: Disclaimed

2.

John read once, during his psych rotation in medical school, that it took approximately thirty days to break a habit.

His transition had been slow and smooth - he hadn't even realised he was doing it - but he was still vaguely aware of this tendency he haboured, this peculiar habit of truly believing Sherlock was there, and so he had to force himself not to speak aloud or laugh at a sarcastic joke or scold the younger man for behaving recklessly.

It really was, John mused, a bit like coming off drugs.

He quickly learned little coping strategies, though. Instead of trying to slip seamlessly between the two entities that were Holmes and Watson, he simply...merged them. He wasn't sure how, wasn't even sure he could take the credit for a phenomenon his mind turned to almost out of self-preservation - but there it was. He felt safe again, because John and Sherlock would never be separated again, a dynamic duo forever, they'd always balance each other out. John could possess Sherlock's ability to figure out precise patterns, combinations and crucial details while still understanding the importance of apologising for ruthlessly attacking someone's weakest points. He understood when to keep his deductions to himself in the name of propriety, or when to sneer and take someone down several pegs to intimidate them into talking.

Within a month, he knew how to smile and charm and talk his way out of any situation, unconsciously acquiring an almost mesmerising quality to his presence, all the while taking in every detail of the scene and adding it to his mental hard-drive for later reference. He rarely lost his temper, knowing he was likely to get more information with a charismatic trance than a cold interrogation; and perhaps that's why the hybrid worked so perfectly: on the outside, the world saw perceptiveness and dedication and an impressive ability to get just what he needed (with very little coercion whatsoever) - the essence of Watson, pure and intense - and on the inside his brain worked furiously, a whirlwind of cunning and careful strategies with 30 or more alternates should his first fool-proof plan fall through.

Though it never did seem to fall through.

He wasn't a genius like Sherlock, but damned if he wasn't brilliant. He could read people, in quite a different way to how Sherlock ever did. Sherlock relied on observation of small details and applied them to knowledge to create Fact. To some degree, John did this too - any slightest movement or anomaly (a muscle twitch, a flash of something in their eyes, a too-stunning performance, an over-bitten lip) gave him pause to wonder at their motives and sincerity. But the difference between himself and Sherlock was he understood human emotions, and he knew people could feel more than one thing at once - could have more than one motive and could feel more than one way about it.

So therein lay his success. He could manipulate them masterfully - witnesses and criminals alike - by appealing to their humanity.

And boy, was he good at it.

"That," Lestrade said, cocking his head to the side, "was incredible."

"Just doing my duty for Queen and Country," John said with a small smile. He watched as they took the screaming woman away.

"What gave her away? I was totally convinced..."

"So was I, at first," John lied, since he knew Lestrade would hate looking like a fool. "But she wasn't reacting right for someone who'd just 'lost' a son, you see. There are all kinds of reactions to grief - believe me, I've seen loads of them on the field - but in response to the death of a child? Usually we get things like shock or crying or denial. Anger makes sense as well. She just hungrily wanted to know every detail, like she needed to relive the crime or make sure we'd paid attention to the right bits."

Not to mention the blood underneath her fingernails is faded but not quite gone, suggesting she washed her hands in a hurry and neglected to scrub all parts. The blood appears to be about two and a half days old, give or take three hours, which her 'alibi' wouldn't account for, John thought wryly, keeping it to himself.

The blood pattern on the carpet suggests the body was dragged 3cm; even for such a tiny distance a woman of her diminutive size would experience muscle strain, hence the inordinate level of paracetamol found in her urine sample when she haughtily consented to that drug test. Her clothes are rumpled but unstained - she changed immediately following the murder but has been wearing the new pair ever since. They are a poly-cotton blend, made here in Britain and perhaps serving as a protest statement regarding overseas child labour laws, and are consistent with the others found in her closet, as well as the blood-spattered vest and jeans hidden in air vent...

Considering her fondness for being green and wearing organic clothing, you'd think she'd be a bit more concerned about polluting the air.

John almost snickered at Sherlock's impropriety before remembering, with an inaudible sigh, that Sherlock wasn't there anymore.

Well deduced, John.

Sherlock had become him, now. The morbidity he kept hidden behind that flawless smile.

Or maybe John had become Sherlock, except with softer edges and a very hypnotic charm.

Or both. Intertwined. Inextricable. And yes, of course, he understood how what he was doing was...dubious at times...but it got the bad guys behind bars and it kept the force happy and it made him feel useful. And it was just another means to an end, right? No one was getting hurt. And he had to hold the fort until the Real Sherlock got back, which could take years.

Nice to see someone at the Yard with some intelligence.

John smirked, head bowed so Lestrade wouldn't see. You're not real, he thought with a strange sort of amusement. You're just the side of me that was always there but afraid to be anything but what society wanted.

He knew this for a fact, because the flesh-and-blood Sherlock would never compliment him in his life; John's essence had...poisoned him somehow, diluted him, and it made John feel incredibly powerful and intrigued and disappointed at the same time.

But he dismissed the thought quickly, finding he wasn't worried overmuch. With a laugh, he bade Lestrade goodbye and told him to give a holler if anything interesting came up.

"So!" the Doctor said happily, as John set about making a pot of tea.

John didn't miss how he'd instantly scrambled the signals, or something, of every bug in the flat upon walking in, using a peculiar, metallic, long shiny stick thing that Mycroft would likely bite his arm off to have a look at.

Then again - Mycroft. Maybe he'd invented the bloody thing.

"How's everything coming along?" the Doctor asked cheerfully.

John wasn't convinced he could trust the man - in fact, just that they were no longer being recorded could be just as troubling as it was reassuring. But either way, he reckoned they had about twenty minutes before Mycroft noticed something was wrong, and twenty minutes didn't suggest a long-term commitment or immediate danger.

John could hold his own for twenty minutes.

He took a leap of faith.

"There's not much in what he left me, I'm afraid," he said, pouring the Doctor and himself each a cuppa. "I know enough now that there's a whole network in the woodwork needs taking care of and he can't emerge too soon or..." he grimaced. "Stuff could go badly."

"Understatement of the century," the Doctor agreed, taking a sip. "Well, no, not quite of the century, sorry, that was an overstatement; I'd say the - hang on! This, this tea, it really is much better than the cafe swill, and frankly I'm rather impressed you didn't even try to poison me!"

John gave him a puzzled smile. "I do have morals, you know."

The Doctor shook his head. "Morals, yes, them, of course, but it more comes down to practicality. You see I can be of use to you."

"Can you?" John challenged, but found there was no heat in it: simple curiosity coloured his tone. Really, Sherlock? he thought incredulously. Am I no longer even capable of annoyance now? "Look, I'm not trying to be impolite, it's just you've got this infuriating tendency to dangle information in front of my face and while I'd normally be content to play cat-and-mouse for hours, we're rather somewhat limited on time here."

Realisation dawned in the Doctor's eyes. "Ah. Yes. Right, of course." He checked his watch. "Seventeen minutes, would you say? Let's get cracking. Show me what you've found."

"I've got...journal entries and a map," John said lamely, getting them from underneath the floorboards. "He knew anything electronic would be intercepted and the map was in a code only three people could decipher."

"Five," corrected the Doctor distractedly.

"Five?" repeated John. Then, understanding, "Oh. Well, four then, at the moment. I've been focused on these journal entries, sussing out his bloody awful script."

The Doctor made a nondescript noise. "I think you'll find the map's more straightforward if you know how he thinks." He looked up at John piercingly. "And if anyone knows how he thinks, John, it's you."

John brushed this off. "You aren't suggesting that I should - "

"No! Don't follow him, you'd be killed in a heartbeat. Woodwork, remember? But you can know where he is, and when." The Doctor shoved the map John's way and snatched the journal out of his hands. "Ten minutes," he added absently.

John ignored him. "That where and when stuff's only accurate if something doesn't, you know, change," he pointed out gingerly, then pushed the thought away, beginning to decipher the codes more quickly now.

The Doctor looked up, smiling with an almost puppy-like enthusiasm. "That's what makes it all so very exciting, John. Life's not very accurate, is it? Life's not meant to be lived on paper."

John frowned. "We're talking about a person here, Doctor. Decorum?"

Confusion flickered across the Doctor's face. "What? Oh, yes, course." He regrouped and turned to stare at John intently. "You have to trust him," he said softly. "You have to trust that he knows what he's doing, and that he'll make it back to you alive."

John felt disturbingly dissected, then - sliced open, examined, vulnerable, raw. He hated it. "He takes unnecessary risks," he hissed. "He only cares for the end result, even if it means hurting himself and those he loves. Emotions terrify him. He can't connect. He has little sense of self-preservation and refuses to ask for help. He's too brilliant and it's all a bloody game and he finds the danger extremely fun."

The Doctor's expression did not so much as flicker. "He sounds very human, then."

John turned back to the map. "Don't let him hear you say that."

"I expect he already knows. Five minutes."

John nodded. "You ought to make yourself scarce. I'll deal with the fallout. I'm told I have a persuasive smile."

The Doctor smirked. "So I've heard. Thanks for the tea and the brilliant chat. Don't lose hope. Think of it like having a bout of flu - always feels worse before it gets better. Be seeing you!"

In a flash he was gone, and John quickly re-hid the map and journal.

Two minutes later, as if on cue, his phone vibrated.

The text read:

Electrical problems? -MH

John deftly responded:

Exterminator. -JW

I do sympathise with your plight. Vermin are a recurring issue in this part of the city. -MH

I've come to expect it, living here. -JW

Brief bout of radio silence, then:

Curious as to how you found said exterminator. His company was not familiar to me. -MH

John paused. Interesting. And highly unusual for Mycroft to willingly give out information such as that. He rolled this over in his mind before simply writing:

Freelance. -JW

There were a few minutes' silence before Mycroft replied.

Care to go for a walk? -MH

Outside the window, John could see a familiar car pulling up. He narrowed his eyes in thought, considering all the possible dangerous consequences and outcomes of this rendezvous, before grabbing his coat and keys and heading out the door.