Hello - so wrote this after the first episode of this awesome show, and thought I'd upload it. It does feature a bit of light romance too to keep all those out there who are into that happy. I like it too. I was eager to explore the friendship between John and Sherlock, whilst having a bit of fun. I love London; it's a great character. I apologise now if the mystery or the cases aren't very clever; I'm not Stephen Moffat or Mark Gatiss! But hope you enjoy anyway - it does feature an OC who is based on one of the original characters but I have reworked it and made it my own. Thanks! RdF

Chapter One – Cohabitation

'Ah, John love, I was hoping you'd be back soon,' Mrs Hudson said, immediately pouncing on John Watson as he stepped through the door of 221b Baker Street after a long day at the clinic. Locum work was, as Sarah had told him when he went for the interview, rather mundane but the clinic was always packed with the general public and their problems and so he never had a moments rest. He'd been particularly inundated with worried mothers and their babies today; the cold winter months had left them with coughs their little bodies couldn't shake and none of the parents would leave his examination room without prescription slip in hand. He would have thought a former army doctor might have a little more resolve and determination when telling someone their son was fine but he'd come to the conclusion the British Forces might have won the war by now if they recruited stubborn mothers whose children were unwell.

"Is something the matter Mrs. Hudson?" he asked wearily, noting her worried frown. She glanced up the stairs, seemingly unsure what to say, before edging forward a little bit.

"Er...it's Sherlock. There's been some strange noises coming from upstairs - banging and crashing, that sort of thing - and when I went to see if he was alright," the elderly woman told him in a low voice, "he simply said 'not now Mrs. Hudson'. The doors been shut all day." As if to oblige her, there was a bang above them.

John sighed and closed his eyes briefly. They were both used to Sherlock's bizarre behaviour and strange idiosyncrasies but that didn't mean the occurrence of such things were easy to deal with.

"I'll go speak to him," John concluded, glancing up the stairs as she had done, bracing himself.

"Oh thank you dear," Mrs. Hudson smiled. "I wouldn't normally mind, only it sounded dangerous - you know what he's like - and I'd hate to think he'd hurt himself."

John managed a smile. "No, that would be terrible," he replied sarcastically, as he began to pace the stairs slowly, ready for whatever possibility lay behind the door to the flat. Yes, it was quite possible that whatever his flatmate was doing, it was dangerous. After all, it had not been that long ago that he'd come back to find Sherlock randomly firing bullets into a wall.

John wasn't a detective but he'd managed to work out that Sherlock was a difficult character to put into a neat little box. He had known him only a few months, during which time, Sherlock Holmes had proved himself to be the most selfish, conceited and apathetic person John had ever known; he was essentially a child trapped in a tall, angular man's body, devoid of much compassion, with none of the normal attributes of the 'human condition'. Everything bored him - normality bored him. His sole passion in life was chasing after mystery and intrigue, solely to unravel it and challenge his intellect. He never cleaned the flat, sometimes didn't talk for days, and never ate when he was working. He had not been wrong when he had remarked he 'must be a difficult person to find a flatmate for'.

But he was also extraordinary. His mind moved faster than the time it took for someone to walk through a door, and he'd have deduced their life story in that time too. John had seen it first hand, and been on the receiving end. Sometimes John didn't have time to feel utterly amazed before Sherlock had done something else that turned his admiration into infuriation.

Whatever was going on behind that door (and he could hear the sound of Sherlock's quick pacing), it had come after a dry bout; three days where Sherlock was so defunct by the lack of interesting cases, John had found him lying upside down from the sofa at two in the morning trying to read a book on hieroglyphs. Everything, it seemed, was a little more bearable from that angle.

"Sherlock?" John tried, rapping his knuckles on the door and getting close so he could talk through the wood. He tried to turn his key but it wouldn't budge - Sherlock's must be left in the lock on the other side. "Can I come in?"

"Not now John," came the reply. "Busy."

"Doing what exactly?" he said calmly, though he couldn't hide his impatience very well as the words slipped past his teeth.

"Working. I'm almost...there - we're out of milk by the way."

"Last time I checked you were perfectly capable of going to the shops, especially seeing as you don't have a real job and could pop out any time. You know, it'd be really great if you could let me in, and then I wouldn't have to talk through the door."

"Real job...I'm on the brink of a critical breakthrough, one that may save an innocent man from prison. Real job indeed," John heard him mutter.

"Right, sorry. I thought you didn't have any cases?"

"Something interesting came up, obviously." A pause. "How was lunch with Sarah?"

"How could you possibly know I had lunch with Sarah?" John asked, feeling himself subdue a little as Sherlock brought up his colleague whom he'd been seeing for some time. He was still a little shy when it came to talking about her, and he knew Sherlock found human relationships ridiculous.

"Simple," called back his flatmate, in a bored, wearisome voice. "You didn't pack lunch today and you left wearing your pale blue shirt. Not a shirt put on simply for patients - little more expensive and better cut, far too good for sick people - so you must have been meeting someone for lunch. Could have been professional, but the aftershave suggested otherwise. You're not the sort of man to have several women on the go, and since you mentioned Sarah the other night, in that pathetically adoring voice usually associated with people in the early stages of a relationship, I assume you're still seeing her. Also, I overheard her chance remark the other week about 'how nice you looked in blue' which must have gone in because every time you've arranged to meet her since you've worn some shade of blue." There was a sudden scraping, which sounded as Sherlock was pushing something across the floor and true enough when he answered, he was out of breath. "Pretty logical conclusion, wouldn't you say?"

"Yes, you're very clever," John said, looking at his watch and looked down at his blue shirt. "Look I've had a long day - I'm tired and I'm hungry..."

"There's no food either."

"You're joking."

"Innocent man, John. Prison." There was a loud smash.

"Open this bloody door!" John shouted, hitting it with his fist, losing all shred of patience he had left. He didn't enjoy the feeling of helplessness, or the constant feeling of being on the outskirts of Sherlock's mind.

It opened unexpectedly leaving John a little startled. He lowered his fist and straightened his jacket, swallowing before addressing the man standing in the doorway, who was wearing a small smile.

"Thank you," John said slowly, stepping past as Sherlock stood aside to let him in. He breathed a small sigh of victory until he saw the room.

"What the bloody hell happened!" he said as he looked around at the utter chaos - more chaotic than usually that was. Sherlock functioned better it seemed when everything was scattered from one end of the room to the other, claiming he knew where everything was. Mrs. Hudson, John knew, did her best to tidy and dust when they were out, but it was nigh on impossible at times. Sherlock had also told her not to bother, because she seemed to remove items that she deemed inappropriate or morbid, and he'd still not forgiven her for the loss of his skull.

But this was something worse; he'd moved the furniture round and changed everything, scattered papers, the windows were shut, locked and the curtains haphazardly drawn, some chairs were knocked over and when he placed his foot down, he heard the crunch of glass beneath his feet.

"Were we burgled?" John asked, though he knew that wasn't what had happened.

"I'm recreating a crime scene," Sherlock explained, looking around with his hands on his hips.

"Recreating a crime...is that my mug?" John cried incredulously, pointing at a shattered cup on the floor.

"Yes. None of the other mugs were...quite the right size," the taller man said, without a trace of remorse as he wandered over to a stack of paper. He seemed to check himself, turning on his heels slightly to face John.

"Did it have a sentimental value?" he asked blankly.

"No, but that's not the point. Look at this room! Didn't you think about mentioning that you planned to do this? Or, here's a radical idea, asking me if I minded you ransacking the flat!" John started trying to tidy up. Sherlock shot forward, and yanked the papers from his hand, dropping them on the floor.

"You weren't here. Don't touch anything."

"I have a phone."

"Too busy to text. Besides, my phone is my jacket pocket."

John cast his eyes towards the coat on the back of the door, metres from the other man. "Unbelievable."

"What was that?" Sherlock murmured.

"Nothing. So what's this case then?" John asked, not sure where to sit or stand, bobbing to sit in his armchair and noticing it was on its side. "Must be pretty important if you've had to go to these lengths to solve it."

"Not particularly," Sherlock replied pulling a book from the shelf, consulting an A4 photograph and then throwing the book into a corner. He stood on a coffee table to see where it had landed and jumped down with the boundless energy he only possessed when he was working. "But it's got some degree of intrigue so I thought I'd take it on."

"Anything I can help with?" John sighed.

"Can you tell me what's wrong with this picture?" Sherlock asked, gesturing around the room before ruffling his hair in thought.

John raised an eyebrow. "I could tell you a few things that are wrong with this picture."

"Oh for goodness...are you still upset about the mug? I'm sorry," Sherlock said in a dismissive, irritated voice.

"No you're not," John retorted but sighed and shook his head. "What am I supposed to be looking for then?"

"The answer to this," Sherlock said, flicking a photograph with his long fingers as he held it up for John. The doctor took it as Sherlock moved to the window and pushed the drape aside slightly to look out.

"This is the original crime scene," John stated, looking at the photo. "What's so special about it then?"

"It was the impossible break in," Sherlock said languidly. "The room was locked, the windows were locked, and the chimney had been blocked years before. Someone broke in, did this, found what they were looking for and left."

"Did they take anything?"

"Nothing of real value, but a very sentimental object to the owner of the house. A book."

"A book?" John said, blinking.

"Well, a diary. And the woman is very eager to have it back since it contains some rather scandalous entries about her liaisons with politicians," Sherlock said with a gleeful smile. "Which has always struck me as particularly stupid."

"What - sleeping with politicians?" John asked with a snort.

"Writing it down. Blackmail, waiting to happen, which is exactly what our poor Miss Isaacs is afraid of." Sherlock paused and ruffled his dark curls in frustration. "She's getting married and putting her checkered past behind her, but she's not eager for her cavorts to go public."

"I shouldn't expect she is," John said with a faint smile. "Might put a downer on their relationship."

"I'm not concerned with that," Sherlock said, waving a hand. "And it's bothering me that the thief hasn't made contact, demanding hush money." Sherlock looked at him. "Did you say you were going to make coffee?"

"No, I..." John paused as his flat mate flashed a brief smile. "Would you like a coffee Sherlock?" he asked, clenching his jaw.

"Oh, how kind. Black. Two sugars."

John heaved another great sigh and pulled off his jacket. It was like living with a child; no thought for anyone but himself, Sherlock lived in a small world where the earth revolved around him and only him (rather than the Sun - a piece of information that Sherlock had admitted to 'deleting' as it 'wasn't important', which in John's opinion summed up the other man eloquently). Doing something like this was entirely like him. Neither did John expect Sherlock to take initiative and begin cleaning up the room once he'd solved the case.

Flicking the kettle on, John leant against the counter and glanced through at Sherlock who was studying the picture closely, and witnessed him toss it over his shoulder with a loud cry of frustration before throwing himself onto the sofa (which was now where the desk should be). His fingers went together in a pensive expression; eyes closed, deep breath, clenched jaw.

"What are your thoughts on Miss Isaacs then?" John asked when he brought Sherlock's coffee through, frowning as he looked for somewhere to put it. He settled for the radiator.

"Vulgar. Particularly vain and shallow breed of woman. Not very clever," Sherlock replied without opening his eyes.

"Don't hold back, will you," Watson replied quietly with a smile. "Do you think she's lying then? That she took the diary as a publicity stunt or something?"

"The thought crossed my mind until I met her - she was wearing her engagement ring which was particularly eye catching - obviously genuine, Cartier, two point five carat. But then there was her cheap acrid perfume, fake designer clothes, her smoking habits. She smoked two cigarettes in the half an hour we spoke - not an expensive brand. Her nervousness is entirely selfish; she's anxious her fiancée will find out, and he's far richer than she is. She stands to gain more married than she would as the latest political titbit." He clicked his tongue. "She was fairly transparent."

"Does she love him or not then? This fiancée. She sounds like a gold-digger."

Sherlock's eyes shot open and his head turned to the other man with a puzzled frown. "What's that got to do with anything?"

"Obviously nothing," John said slowly. "Carry on."

Sherlock returned to his pensive state. "She has an alibi for the time of the robbery. Nobody else has a key to the house - no family, and someone who owns knock off Louis Vouiton wouldn't have a housekeeper."

"Not even the fiancée?"

Sherlock inhaled a deep breath, almost as if he was tired of explaining. "Would you give your fiancée a key if you'd been fooling around with half the Shadow Cabinet John?"

John bunched his muscles and swallowed hard. "No...But if I were a rich man dating a girl like that, I'd find it fishy if she didn't give me a key," he said a little haughtily. "Wouldn't you?"

Sherlock made a sound with his throat and sighed. "Perhaps."

"What about one of the politicians she slept with? Surely they'd want to erase the evidence," John suggested, sipping his coffee.

"As far as she knows, none of them were aware she kept a record of their time together, but we won't discount it. Spectacularly naive woman," Sherlock added, pinching the bridge of his nose. "I'm over complicating it. The scene is too impossible, too strange – there must be a simpler explanation."

John knew better than to push Sherlock while he was thinking, and thinking he was because for the next couple of hours, not a word escaped the other man's lips. Mrs. Hudson knocked timidly on the door, and John leapt hurriedly to reach it before she walked in and saw the state of the place. She glanced at him, and tried to look past him, but John gave her a wide smile and closed the flat door behind him, so she simply handed him a dish of pasta bake. It smelt delicious and he hadn't realised how hungry he was; Sherlock's antics had once again obscured the normal trivialities of human life. Sherlock did not eat while he was working, and there had been cases they had worked on when the sudden pang and realisation that he had not eaten for nearly two days hit John with such shock he almost had to laugh at himself.

"He's on a case then?" Mrs. Hudson whispered as John took the pasta from her gratefully.

"Er, yes. Big case. Can't be...disturbed...are these courgettes?" he laughed nervously as she tried to walk into the kitchen. Luckily he'd slid the partition glass across that divided the kitchen and living room, and none of Sherlock's handiwork was visible.

"Aubergines, love." She craned her neck to see Sherlock's silhouette through the glass, stretched out across the sofa.

"Right. Aubergines. Good. Thanks, Mrs. Hudson," John smiled politely, standing stock still, indicating for her to leave.

"And the banging?" she asked with a wrinkled frown.

"Got a little too excited watching daytime TV."

"Oh, I can understand that," Mrs. Hudson laughed, forgetting her curiosity and heading for the stairs. "Jeremy Kyle had me in an absolute stew for hours the other day - the nerve of some people you know. All these young parents, shirking responsibilities. If you've made your bed, you've got to lie in it, I always say, and not with three different people...but I don't have to tell you. A nice young man like you understands monogamy." She patted his arm fondly and headed down stairs as he breathed a sigh of relief.

Ten minutes later, John was spooning some pasta onto his plate when a sudden cry from the lounge made him almost drop both the plate and spoon. Sherlock appeared at the arch of the kitchen, sliding the doors open with a triumphant expression, hair slightly wild, and his eyes wide with excitement.

"Staring us the in the face John!" the man cried. John blinked, recoiling from Sherlock's outburst and followed him.

"Sorry – what is?"

"It wasn't a robbery at all! The book never left the room."

"What? Why break in to not steal something and then make it look like it had been?"

"The thief hid the book to scare Miss Isaacs." Sherlock moved around quickly; the lethargy he'd experienced moments before had seemingly nonexistent. "Don't you see?" he exclaimed, staring at John. "The fiancée had a key made – probably snuck in to wait for her as some kind of surprise. Miss Isaacs isn't a careful sort of person – kept a diary about who she'd slept with for goodness' sake – didn't feel the need to hide it either. Why bother when no one else has got a key? He finds it, reads it, decided to teach her a fairly harmless lesson by making it look like a mysterious political break in. He was upset enough to make it look convincing. Of course if anyone figured out he had a key, he couldn't be caught with the book – he'd be arrested, she'd break up with him – to his stupidity, he actually loves her. No one spends that much on an engagement ring unless they're serious. So he hid it in the room, trashed the flat and left again. That's why she's not received any word from a blackmailer, that's why it seemed impossible."

"Where's it hidden then?" John asked. Sherlock grabbed the photograph and showed it to the doctor.

"In plain sight." He jabbed the page with a finger and grinned. John squinted and laughed nervously.

"You're kidding."

Sherlock pulled out his phone, which had beeped inside his pocket while he'd been giving his conclusion. "The art of disguise is blending perfectly into your surroundings. Where else would you hide a book?"

"In the bookcase - seriously?"

The other man strode across to the doorway and pulled on his long coat so it twirled with a dramatic finesse that seemed to go hand in hand with every movement the man did. "She didn't expect it to be there; look at her bookcase - some of the spines are backwards - she's careless with things, especially books - it'd be easy to hide a book there. Everyone was too focused on the break in to notice that."

"Fantastic," John said, scratching his head as Sherlock strode to the door. "Where are you going?"

Sherlock spun on his heels and took a deep breath. "Fresh air. And Lestrade has summoned us," he added waving his Blackberry at him.

"But what about this mess!" John laughed incredulously.

"Mrs. Hudson can do it," Sherlock shrugged. "She likes taking care of us."

"Er, she likes to dust occasionally and give us leftover food," John explained. "It's not fair to ask a sixty year old woman..."

"Sixty two."

"Sixty two year old woman...to clean up your mess! She has a bad hip."

"Fine. When I get back."

"And don't think I'm going to help. This was your –"

"Are you coming? There's been a murder at Shepherd's Bush," Sherlock asked as if John had said nothing at all, wrapping his blue scarf round his neck. The doctor bit the inside of his cheek, frowning and looking around the room with a reproachful look. Sherlock blinked expectedly with a smug smile - he already knew the answer.

"Yes," John sighing grabbing his coat and pulling on quickly. Of course he was going.