Disclaimer: I do not own Sherlock.

A/N: For Sarah1281's birthday! Enjoy your full-day forced training session for something you don't even want to do, and also this fic!

When John H. Watson, recently invalidated Army doctor, woke up that morning, he had not expected to come out of his bedroom (after a long internal debate about whether it was even worth it) to discover that his previously-bare flat had magically become fully furnished in the night.

After a few moments of panic and a few more moments of prodding the mysterious sofa, coffee table, new chair, and very-strange horned wall decoration with headphones, he had simply accepted that he'd finally gone mad, and went to make himself a cup of tea.

He had expected this, after all. Losing his mind. In some ways having it over with was sort of a relief. At least it wasn't looming over his head anymore, making his pistol look friendlier and friendlier. Also, if he were mad, maybe his landlady would let him continue to live in 221B despite his inability to pay another month's rent, even with the veteran discount she'd graciously given him. As long as he wasn't crazy and violent, this was definitely something he could see such a nice old lady doing.

The kettle boiled presently and John made himself a cup of tea, using whole milk as a treat to himself to commemorate the day he'd finally cracked. He sat down at his new kitchen table and sipped his tea, gazing around the flat.

He liked it a lot, especially with the new décor. Even the horned thing was okay, though he couldn't imagine where his subconscious had gotten it from. There was also a pile of letters on the mantel with a knife through them.

It really, really looked like an additional person lived here, now. A messy person who left piles of books and paper everywhere. Had his brain dreamed him up a wife? That would be sort of nice. Hopefully she was pretty enough to make up for how she trashed their sitting room.

He heard shuffling upstairs and happily assumed it was his wife. It was coming from the spare room he had previously used to store... well, his suitcase. He didn't have much else. Now he could see it tossed unceremoniously by the window, next to... a violin case? Fantastic, his wife must play violin. He gave himself a mental pat on the back for his good taste in hallucinated spouses.

The shuffling continued, and John waited patiently for his first glimpse of his wife.

A moment later, a tall, thin, man appeared at the foot of the stairs wearing pajamas and a blue robe. John blinked and took another sip of tea. Alright, a man. If that's what his subconscious wanted.

"Hello, then," he greeted the specter with the wild hair. "You're the wife, I suppose?"

The newcomer raised an eyebrow. "I'm Sherlock Holmes, your new flatmate."

"Flatmate?" John echoed.

Sherlock stared at him. "You put out an ad."

"No, I know," John assured him, taking a sip.

Sherlock watched him for a moment longer, looking both horrified and bewildered. John stared back. It was too bad his brain had given him a flatmate instead of a wife, he thought. But a lonely mind will do as it likes.

"So your name is Sherlock Holmes," he said after a while. No reason not to be polite. "I'm John Watson." He extended a hand. "Nice to meet you."

Sherlock crossed to him and shook it primly. "Sussex or Whales?"

"Excuse me?"

John's imaginary roommate smirked. "Are you from Sussex or Whales, before you were in Afghanistan?"

"Sussex. Sorry, how did you...?"

About halfway through Sherlock's very-animated explanation about weather and accents and hair curliness, John remembered that Sherlock was from his mind, so of course he knew everything about him. He tuned the rest out but nodded politely from time to time, thinking about what Harry would say when she eventually heard him talking to someone who wasn't there.

"So what do you do?" he asked when Sherlock seemed to be done talking.

Sherlock blinked at him. "Excuse me?"

"What do you do?" he repeated clearly. Maybe his hallucination was partially deaf. John's therapist would almost certainly have something to say about that. A projection of his leg, maybe?

"You don't seem surprised that I just told you your life."

John shrugged, taking another sip of tea. "Well, you would know everything about me, wouldn't you?"

Sherlock stared. "Right..."

"So. Really. What do you do when you're not here, being my imaginary flatmate?"

"Imaginary?"

"Right, sorry, didn't mean to offend."

"I'm a consulting detective," Sherlock answered finally. He waited for the follow-up question which usually ranged from a pleasant 'what is that?' to 'piss off' just on principle.

"That's nice."

Sherlock was definitely disturbed, now. "Your sister is divorcing her wife because she's an alcoholic," he said flatly. "And your mother died in a car crash when you were sixteen. Your father is an alcoholic, too."

John nodded again. "That's right."

"I moved into your flat without telling you first and I play the violin at all hours, often quite poorly."

John nodded. Well, it certainly wouldn't disturb Mrs Hudson.

"I keep body parts in the refrigerator."

"Tea?" John stood up to make some more.

Sherlock rose to follow. "Some days I talk nonstop and sometimes I don't talk for days," he said louder.

"Sugar?"

"I may keep cigarettes stashed around the flat, you know."

"No, I don't take sugar, and since I'm really just making this for myself in the end..."

"John!"

"Hm?" He turned to look at Sherlock, calm and patient.

Sherlock gazed back. "Nothing I'm saying bothers you," he said, more a statement than a question. "Me being here doesn't bother you."

John shrugged. "I was bored anyway."

Sherlock grinned. "Dinner?"

"Starving."

The prompt was: Instead of John moving in with Sherlock, John has the flat and wakes up one day to find Sherlock has moved in overnight.