John unlocked the door to 221B Baker Street, entering cautiously so as to see what mood Sherlock was in as soon as possible.

The apartment was blissfully empty. John sighed and went into the kitchen to set down the groceries he was carrying. He put the kettle on then opened the fridge and began putting things away, humming as he worked.

So of course, when Sherlock came in a few moments later, slamming the front door like the flames of hell were upon him, John nearly jumped out of his skin. He heard Sherlock set something heavy down.

"Good Lord, Sherlock. Are you trying to kill me?" He asked, moving the kettle off the stove.

"You have a cat hair on your jacket." Sherlock said by way of reply, passing the Kitchen and darting into his study.

"Excuse me?" John asked. "That didn't sound very much like 'sorry for scaring your knickers off, John.'"

"You better be keeping your bloody knickers on." Sherlock said, crossing in front of the kitchen door and pulling books off shelves.

"All right. What's so important about cat hair that you can't even give me a proper greeting?" John asked.

"It's on your jacket." Sherlock threw back. John looked down.

"I'm not wearing one."

Sherlock passed the doorway again, pausing to look John up and down.

"So you aren't." And he was off again.

"I couldn't wear my jacket because I haven't been able to find it, Sherlock. Would you know anything about that?"

Sherlock paused his pacing in the doorway again.

"Haven't a clue. You should be more careful with your things."

John sighed, pinching the bridge of his nose.

"Sherlock. You're wearing my jacket."

"So I am."

"And Sarah has a cat named Ginger."

"So what?"

John resisted the urge to scream. Why were consulting detectives SO AGGRAVATING.

"I was at her house last week to pick up a few things. I saw the cat while I was there."

"John, you hate cats."

This conversation was going nowhere.

"Give me the jacket."

"No. I'm wearing it." Sherlock passed the kitchen once more.

"Give me the damn jacket, Sherlock Holmes!" John shouted. Sherlock backtracked into the doorway.

"What's mine is yours, what's yours is mine." Sherlock said airily.

"No, that's not how you seem to work. With you it seems to be that everything is yours and I get the short end of the stick!"

"I seem to recall that you have three Jackets, John. I only have one. And that one jacket is at the Tailor's."

John sighed. "Yes, I did have three. But now I don't."

"The brown wool?"

"In the garbage. You burnt a hole through the back."

"The gray?"

"At the cleaner's. You spilled ink all down the front."

"The longer black one?"

"You're wearing it."

"So I am. There's a cat hair on it, John. You really must take better care of your things."

John ground his teeth together.

"If it makes you happy. I will go purchase us both a new jacket. Since we apparently wear the same size."

"A little bit longer in the sleeves if you don't mind, John." He called as John picked up his keys.

"You're disgusting." John growled.

"What was that?" Sherlock asked, resuming his pacing. "I couldn't quite hear."

"Nothing." John said, temper flaring. He moved to the door, but was stopped by the large box by the door. It held a bag of cat food, a climbing structure, some toys and a cat crate.

"What the hell is this? Sherlock?" He nudged the box with his foot. Sherlock's footsteps came in behind him.

"John. The cat hair on your jacket isn't from Ginger." Sherlock said. John turned, and his eyes nearly bugged out. Sherlock was holding a little gray striped kitten with a bow around its neck.

"But Sherlock, you know I hate cats." John said, not really comprehending. "I'm allergic." Sherlock rolled his eyes and shoved the kitten into John's arms. John held it away from his at arm's length.

"The kitten is part of an experiment." Sherlock said, disappearing into his study again. He emerged a moment later with a syringe full of an odd colored liquid.

"Sherlock, don't you dare- ACHOO!" John sneezed. Sherlock advanced, and John held the kitten out as a shield, sneezing wildly.

"Now, now, stop struggling." Sherlock said, easily backing John against the wall and stabbing his arm with the needle.

"Ouch!" John yelped, nearly dropping the Kitten, who meowed.

Sherlock took a triumphant step back, watching John. John stared back.

A full minute passed, and John didn't sneeze. He looked at Sherlock, then at the kitten, then back the consulting detective.

"How did you...?"

"I wanted to get you a pet, John, and our lifestyle is suited for a cat. So I had to figure out how to stop your allergies. I think it's safe to say that this experiment worked."

John looked at the kitten incredulously. It stared back. He slowly brought it in to his chest, and she rubbed her face on his shoulder, snuggling into him.

"I thought we'd name her Clancy." Sherlock said.

"O-okay." John stammered, unsure of what to do as the kitten began to purr. He turned and took the kitten into the kitchen, leaving Sherlock to unpack the box of cat things. The consulting detective smirked, very pleased with himself.