It's not something Dean would've asked for himself, but he sure as hell doesn't say no when Cas asks, fumbling over his words and scrunching up his forehead and blanching when he realizes that maybe he should've gotten a ring.
One month later, all the words Dean's familiar with, like "salt" and "shotgun" get overridden with big, important words like "vows" and "venues" that more often than not make him want to run and hide in the Impala and wait for the whole wedding to blow over. Gradually, though, it occurs to him that getting married is more like hunting than he'd originally thought. They're both just litanies of questions. In this case, the first one is "Will you marry me?" and the last one is "Do you take this man?" and there's basically several infinities of queries crammed in between, like "Where's the reception gonna be?" and "What the hell am I gonna wear?" and "Garth, are you really an ordained officiant?"
Dean misses out on the "Will you be my best man?" question because Sam jumps at the title the second Dean tells him about Cas's proposal, trying not to giggle like a thirteen-year-old girl. Charlie, though, Charlie he gets to ask, over diner food, "Will you be my maid of honor?" And yeah, he feels incredibly stupid saying it – it's pretty much how the entire ordeal makes him feel- but the way her face lights up makes it not matter anymore.
"On one condition," she tells him, dabbing ketchup from the corner of her mouth.
"I get to make as many My Best Friend's Wedding references as I want and you're not allowed to roll your eyes once."
Dean's face splits into a grin and he nabs a fry from her. "Deal."
After that all the pacing gets weird, like a broken cassette that skitters rapidly at parts and then slows down at others, skipping some songs entirely. Nights with Cas stretch out and tux fittings in the afternoon slide by; the occasional salt-and-burn with Sam goes almost unnoticed, and then finally it comes to the day-of and Dean finds himself in the restroom of the place they rented out with one leg hanging out the first-floor window.
"Hey," Sam starts, bursting into the room in his fed suit, but he stops walking when he notices what's happening. "What the hell are you doing?"
"Sammy," Dean says, blinking like he's surprised to find his brother there. "Here, can you help me get this window open?" Pushing up at the bottom of the pane, he looks imploringly at Sam, who only glares before striding over, yanking Dean away from the wall and slamming the window shut.
"No." He'd gotten a haircut, Dean realizes numbly- one of the details that had slipped by him in the wake of all the wedding chaos, details like Kevin flying in and the bunker's refrigerator breaking down and the fact that he was getting married. Because there's a big difference between having a wedding and getting married, and Dean had realized this approximately three minutes ago standing in this bathroom trying to make sure his tie was on right.
"I can't, I…" Dean's jaw works but nothing comes out, like a sitcom character muted in the midst of trying to explain away his cold feet with a few witty lines of dialogue backed by uproarious audience applause and laughter. "Look, it's like- it's like Baby. Okay? You know Baby?"
Sam just stares. "The… the car I've lived in since I was six months old? Yes, Dean, I know Baby."
"Okay." Something in Dean's look is familiar, and it takes Sam a minute or so to remember that this is the way Dean looked years ago under the influence of ghost sickness, talking to him outside the car about how crazy they were, how crazy everything was. "So, Baby- Baby I can take care of, you know? Fill her up, keep her clean. Stuff, and- and I don't know, I just don't know."
"You don't think you're going to be a good husband."
With an exaggerated huff, Dean holds his arms out. "Well?" Because even though he's good enough to save the world and good enough to have a home, he still doesn't think he's good enough to marry Cas.
"Alright, look," Sam says, lowering his gaze so he's eye level with his brother. It would always be like this, he thinks distantly, that he'd always have to talk Dean into being happy, and maybe he'd hoped that falling in love and getting engaged would fix things for Dean, but maybe some things don't change. "Cas loves you. You love Cas. That's literally all that matters, believe me. You're gonna do fine." Dean takes a breath, another, nods like he gets it, but he still looks nauseous. "Come on, man, remember how happy you were at your engagement party?"
"I'm surprised you do," he snorts. "You were plastered."
"And I plan on getting good and drunk tonight too, so don't ruin it." Dean looks a little chagrined. "Also," Sam adds, a smiling tugging at the corner of his mouth, "Cas doesn't have a frame of reference when it comes to being married. You could screw up completely and he probably wouldn't even know."
It's bad advice but it makes Dean laugh, and laughing makes him relax and relaxing makes him think more about the angel behind the door than the escape route out the window. "You good?" Sam checks.
"Yeah, yeah, I'm- I'm good." As if to prove his point, he smiles. "Just give me a sec. Okay?"
"Don't run off." Sam slips out the door and Dean does one last tie-check in the mirror before following behind.
When he tells the story of his wedding day, Dean will always say that after that conversation he went straight from the restroom to the terrace outside, but that isn't true, because instead of walking out to the terrace and the rest of his life, first he turns right and goes out the other exit, walks fast to the nearest bench and collapses on it, barely noticing who else is perched there until he sits down.
"Shit. I don't think we're s'posed to see each other before… you know."
"Then don't look at me, look at the car," says Cas. The Impala's set up in front of them, and Sam must've gotten to it because there are beer cans tied to the back, the words "Just Married" written in Enochian on the rear window.
"How're you doin'?"
"Charlie Bradbury tried to give me wedding night advice."
Dean smirks, then- "Wait, how did she-"
"Apparently," Cas says, "she's read about it in-depth on the Internet," to which Dean laughs and lilts against Castiel's shoulder just a little.
Time stretches out like it always does, and though it must be only a few minutes that they sit there staring at that car, it feels like hours, and it occurs to Dean that it'll always be like this, that even though he'll die before Cas does it'll feel like it was forever they spent together, and just as he's realizing what an intensely sappy thought that is Cas squeezes his hand and it doesn't matter anymore.
So they go ahead and have an intensely sappy wedding. Garth gets choked up in the middle of the ceremony. Sam gets drunk, as promised, at the reception and almost trips over Linda Tran. Dean twirls Charlie on the dance floor to Aerosmith and The Who while she laughs. He swings slower, side-to-side, with Cas and wonders how he ever thought this could've been a bad idea.
On the far wall, Sam's holding a flute of champagne and watching them. "Are you trying not to cry?" he says to Charlie, who's leaning next to him running her finger around and around the rim of her glass to make it chime.
"Yeah," Sam sniffs, "me neither."