I've never written for Sherlock before and I've only seen it once so I hope you'll forgive me for the dialogue, etc. being way off from the original.
"What is wrong with him?" Sherlock asked the bartender.
"Him?" he asked, jerking his head at the man swaying on the small stage.
"Yes."
"He's drunk."
"Is that all?" Sherlock inquired, scrutinizing his wasted flat mate who was singing very slurred karaoke to a song he was pretty sure was called "Hot 'n' Cold." Sherlock had known of course that John was very, very drunk. Even a total moron could tell that. However, he was also sure there was something else wrong, something he could not quite put his finger on. He suspected it was some sort of social issue, which would explain why he was having trouble pin-pointing it.
The bartender joined Sherlock in studying the drunken singer.
"I should know that you're no good for meeeeee," John half-sang, half-shouted.
"He's in love."
"What?"
"He's in love," repeated the bartender, returning to washing glasses.
"He just broke up with his girlfriend."
"Maybe he still likes her then."
"But he broke up with her. Said there was a problem with their "chemistry" or something of that sort."
"Then maybe there's someone else," he said with a shrug. "You going to order something?"
"And end up like him? No thank you."
John finished his song and stumbled off the stage. Sherlock rose and went to collect him.
"Come on. You're going home," he said firmly, taking John's arm.
"Someone gunna pay for his drinks?" called the bartender as they passed.
Sherlock sighed, but settled John's tab before steering him out of the karaoke bar. John was leaning heavily on him as they waited for a cab.
"Come on," Sherlock said again as he tugged John inside. "Baker Street, 221b."
"Sherlock," said John vaguely.
"What?"
Bu the drunken man did not reply he just swayed gently with the movements of the cab.
When they reached Baker Street Sherlock practically had to carry John up the stairs and over to the sofa where he deposited his flat mate.
"Sherlock," John began again.
"What?"
"Why were you there?"
"I came looking for you," he said as he found a glass to get John some water.
"Really?" John asked sounding perfectly elated.
"Yes. Here." Sherlock handed him the glass.
"Thanks."
"John?"
"Hmm?"
"Are you still in love with Sarah?"
"What?"
"Sarah."
"Oh." John gave a strange sort of laugh. "No. No, defiantly not."
"But you are in love with someone."
John stared at him with bloodshot eyes for a moment before nodding.
"Who?"
"What, have you're powers of observation finally failed you?" asked John, getting unsteadily to his feet and taking a few steps towards Sherlock.
"John?" he asked uncertainly, taking a step back.
"Sherlock." John smiled for a minute before falling back onto the couch. "Oh who am I kidding?"
"What?" asked Sherlock, now thoroughly confused.
"Isn't it obvious? You can tell a man's life story from his phone, but you can't tell who your own roommate's in love with? Some detective you are."
"I know who it is, John," said Sherlock quietly.
"Really? Or are you just trying to get me to say it?"
"Why would I lie? But you should say it." Sherlock did know, of course. Now that he realized it, he knew too that he'd known all along; he just hadn't come to terms with the fact until this moment. Still, he wanted to hear it from John's own lips.
John smirked at him for a moment before speaking.
"You, you fucking psychopath."
"Sociopath."
"Whatever." And with that, he passed out.
"God, what happened?" asked John, appearing in the living room late the next morning with a hand to his head. "I don't remember a damn thing after the cab and everything before that's not to clear."
"You got spectacularly drunk," said Sherlock without looking up from his book.
"I know that. How did I end up back here?"
"I brought you home."
"Right," said John starting to node and quickly stopping as it made his head hurt even more than it already did. He staggered into the kitchen for a glass of water and some painkiller before coming to sit in the living room with Sherlock.
The pair sat in silence for a few minutes until a vague memory filtered through John's dazed and dehydrated mind.
"Sherlock," he said cautiously.
"Yes?"
"Did I do anything odd last night?"
"You mean besides drunk karaoke?"
"Yes."
"Why?" asked Sherlock slowly, looking up at John for the first time.
"I dunno. I just feel like I did something – or maybe said something – really stupid."
"You were drunk," said Sherlock dismissively.
"Did I say something weird?"
Sherlock considered him for a moment, mentally flicking through the pros and cons of telling him the truth.
"No," he said and returned to his book. If John really was in love with him when he was sober, he needed to come to that conclusion by himself. And maybe when he was sober things would a go little further than an awkward confession. Or maybe it would all blow up in this face. Not that he minded either way of course, Sherlock assured himself, but he certainly wouldn't mind if what John had said turned out to be true.
So what do you people think? Was that a one-shot or should I keep going?