It's Gabriel's fault. (It's always Gabriel's fault, except when it is Sam's fault, especially considering he got Gabriel on board Team Free Will in the first place, and very, very occasionally Castiel's fault, which is always, as far as Dean's concerned.)
They're taking another stab at parleying with the angels through the intermediary of Zachariah the asshole ambassador, Gabriel there to wave his archangel wand and smite the shit out of Zachariah if he tries anything. The meeting time is ass o'clock in the morning despite Dean's hangover, because the world hates him, and at least the meet's in a motel room, which means if things don't go horribly, horribly wrong, Dean might be able to catch some sleep, or at least lie down a few minutes. Dean's not holding out hope.
Gabriel's apparently not a morning person either or he's just plain tired of Zachariah's bullshit. Dean's sick of it, too, but before he can say something witty, cutting, and totally bad-ass, Gabriel decides to cut the tension—or rather, make it explode—by making a joke about how Michael wants to use Dean as an angel condom. And it's not like Dean hasn't made that same damn joke before, but it is just not on.
"Dean," Zachariah says, sounding like Gabriel just pissed in his cheerios, "will do what is necessary."
"What do you think, Dean?" Gabriel turns, smirking. "Going to lie back and think of queen and country?"
"The only angel putting his dick in me here is Castiel," Dean says, before he can stop to let his brain consult with his mouth about not completely boning him, like his mind tripped and fell over the bottles of Jack he drank last night.
"Righ—" Sam starts to agree with him, it seems, on 'fuck you' tone alone, but pulls up immediately to say, "Wait, what?"
"What your face," Dean mutters. "No angels are getting anywhere near my ass or any other part of me," Dean says firmly.
Gabriel, meanwhile, looks absolutely delighted, like Dean has thrown Christmas in July just for him. Turns out he's a morning person after all. "Except our dear brother Castiel, you mean."
And Cas is doing that head tilt thing, like he is both confused and intrigued, as he says, "I hadn't realized it was a possibility."
"No one," Dean says, and his brain is still scrambling to catch up, because it takes him a moment to ask, "Wait, you'd be interested?"
Castiel opens his mouth, but whatever he was planning to say is drowned out by Zachariah making what are probably the most horrified noises in angel history. "We don't lower ourselves to such—such—"
"I seem to recall some Biblical lowering," Sam says in a tone that indicates he regrets even bringing it up, but his inner pedant can't help it.
"And I believe I've already been cut off from the Host," Castiel puts in mildly.
Dean can't believe that somehow they've gone from Round 2,734,363 of how he is not going to be Michael's vessel to discussing his non-existent angel sex life, all while Dean is still hungover.
"You wouldn't actually—" Zachariah begins, just as Gabriel sidles toward Sam and seems about to make a crack about his willingness to do some Biblical lowering of his own, and Dean's head feels like a male jackhammer and female jackhammer are having little jackhammer babies inside his skull.
"No," Dean says. "No, we are not discussing this," he tells Zachariah and Sam and Gabriel, "and no, we are not doing this here," he tells Castiel, who looks like he wants to press forward with this conversation regardless of audience, "and no, I am not letting Michael put his angel dick in me," he tells the world at large, because it hasn't seemed to sink in yet.
"Now, unless someone wants to help me with my hangover, you are all getting the fuck out of my motel room, and I am going back to sleep." Matching words to action, Dean throws himself on the bed and places a pillow over his head.
"It's my motel room, too—" Sam begins, but Dean just takes the pillow off his face long enough to glare. Sam throws up his hands and starts gathering his shit—jackets, keys, laptop.
Zachariah gives him one of those "You will give in someday" looks and disappears. Gabriel smirks at Sam and says, "Let's go somewhere more private and talk about Biblical lowering."
"No," Sam says, making his way out of the door, and Gabriel shrugs.
"Your loss." He's gone almost before he's finished speaking.
Castiel is the only one who remains.
"Was I not clear enough for you?" Dean says. "Get. Out."
"Did I mention," Castiel says, walking forward until he's right next to the bed, staring down at Dean with that inexplicable expression of his, "that I can cure your hang-over?"
"Why haven't you offered before?" Dean growls, because it's not like this is the first time Castiel has seen Dean the morning after a bender.
"You didn't ask." Castiel sits on the bed and leans close to Dean, stopping mere inches away like he's waiting for permission. Dean almost considers telling him to fuck off, but—
Instead of the expected two fingers, Castiel places his lips gently against Dean's forehead, chapped and dry and somehow still kind of soft, and just like that, the jackhammers are exiled, the light loses its stabbing quality, and Dean's head feels clear again. Castiel pulls back just enough to look at Dean, and he's really looking, like he sees Dean down to the soul—and knowing Castiel, he does—and whatever he sees there is enough, must be the answer he's seeking, because he leans forward again, lips brushing against Dean's own this time. Dean doesn't stop him, can't bring himself to stop him, and instead makes a noise low in his throat in response, reaches up to grip Castiel's shoulder and pull him down to Dean's level.
After a moment, Dean pulls back enough to say, "So you're—this is—you want—" Dean trails off awkwardly.
Castiel takes apparent pity on him and says, "I don't need you to be my angel condom, Dean." He leans in so close that Dean can feel each puff of air against his lips, and Castiel's eyelids are half-lowered, pupils blown and eyes fixed on Dean like he can't bring himself to look away. "But I would not object to a little Biblical lowering of our own."
For the first time this morning, Dean finds himself faced with an angelic proposition he can't say no to.
(It's Gabriel's fault, but in the end, for once, Dean doesn't mind.)