Full prompt:
"Jim looks towards McCoy (they are drinking of course), and says in complete seriousness: "I think I might be dating Spock."

Spock is not great with emotion and he's very discrete, so when he starts courting the captain, at first Jim doesn't even notice. It starts small, meaningful looks over chess, invitations to eat together, even Vulcan kisses (which Jim thought were just innocent hand brushes) all favorably received, so Spock thinks that they're on the same page (because judging by Vulcan standards, he's really putting himself out there). But eventually Jim realizes that he hasn't hit on anyone or even thought about being with anyone else for a while now, that he spends about 90% of his time with Spock, and all the physical contact shared probably isn't normal for captain and first officer, or people who are just friends. Problem is he isn't sure if he's dating Spock, or if this is just how all Vulcan's treat their friends, and it's not as if he can just ask him. Cue getting drunk with McCoy and asking the above question."

Not a long fill, but hopefully cute.

(Hmm, come to think of it, this is actually the first slash I've ever written (counting femslash separately). Hooray milestone! =D )

It had all started innocently enough.

In fact, it was so innocent that it didn't even occur to Jim Kirk that there was an 'it' to think about.

But now that the thought had occurred to him, he couldn't shake it. There was definitely an it, but damned if he had any idea what it was.

Well, no. That was a lie. He had an idea. An idea that he kept dismissing easily, but that kept creeping back when he least expected it.

Seriously, it couldn't be.

But there was only one way to confirm that it wasn't true, and that wasn't going to happen.

No way in any planet's variation on hell was that ever going to happen.

But he'd been in limbo for far too long, which was why he was now drowning his confusion with alcohol.

"More brandy, Bones?"

"...was that an offer or a request?"

"I dunno." Kirk stretched for the brandy and poured himself another, then offered the container to McCoy, who accepted.

Jim stared into the glass.

"You drunk yet, Bones?"

McCoy raised his eyebrows. "Why do you ask? Wait, don't tell me. I never end up liking what I hear."

Jim paused, and then took deliberate swig of brandy.

"I think I might be dating Spock."

McCoy blinks. "...I didn't think I was that drunk."

"I'm serious."

McCoy looked at him, then sighed and took a swig of his drink.

"I may regret it, but I'm listening."

Jim rubs his forehead.

"Um. You know how Vulcans never touch anyone? Like, ever? Unless it's life or death?"

"Yeah."

"Spock touched my hand yesterday when he was passing me a Padd."

McCoy snorted. "You sound like a twelve year old gushing over your first crush."

"Bones, this is Spock. Has he ever made accidental skin contact with you? With anyone you know of?"

McCoy hesitated. "...not really, no."

"And it wasn't the first time!" Jim rubbed his head furiously. "That was the first time I noticed, because he actually paused. But now that I've noticed it...Bones, he's been doing it for weeks. And not just might-be-accidental hand brushes, either." He shook his head. "God, Bones, I feel like an idiot here, I assure you. But he's been giving me these indescribable looks, over chess, or over dinner, or-hell!" Kirk shook his head again and leaned back.

"Bones, he keeps inviting me to dinner at his place, and I didn't even think about it."

Bones just looked at him. "Have you, I don't know, asked about it?"

Jim pushed back from the table and nearly fell over. "Shit no! What am I supposed to do? Just go up and say 'Hey Spock, sorry to bother you, but have we been dating for the last two months, or am I just having the mother of all misinterpretations?'" He shook his head again. "Shit, I don't even know if gay Vulcans even exist."

McCoy raised his eyebrows. "It would be logical."

Kirk scrunched his nose. "Huh?"

"Nothing. So..." Bones glanced toward the ceiling and sighed. "...I'm going to regret asking, but...which answer are you hoping for?"

Kirk blinked. "Uh..."

"I mean, didn't you bang every non-lesbian woman on campus? Except Uhura? So I've been kind of working on the assumption..."

Kirk grinned. "Not all of them. Besides, I'd hate to limit my options."

"...why does you being bi not surprise me?"

Kirk shrugged. "If you wanted to know, you should have asked. Or hit on me."

McCoy raised his eyebrows. "Well, there's your other answer."

"...what?"

"You want to know. You won't ask." McCoy made a shooing motion. "So go hit on him."

Kirk blinked. "You can't be serious."

McCoy leaned over and topped off his glass. "Kid, you're drunk. Use it. If you think he's been hitting on you in his way, then go hit on him in yours and see what happens. If bad things happen, blame the alcohol. It worked for me." He took a sip. "Of course, we divorced later, but that was completely unrelated."

Jim gaped. "That...Bones, my version of flirting usually involves some variation on 'hey, wanna bang?'."

"Well, do you?"

"Uh..."

"Wait...wait. No. What am I thinking, don't answer that. I'm nowhere NEAR drunk enough to think about it." He took another drink. "But if you do...drunk alibi. Have fun." He winced. "I mean, good luck. I mean...you know what, never mind." He stood. "Now, if you don't mind, I'm going to go sleep off some of that conversation."

With that, he rose, gave a lopsided salute, and walked away, leaving a flabbergasted Jim in his wake.