Title: What Happens In AC

Pairing: Caskett

Prompt: via castlefanficprompts on tumblr: Anonymous said: (pre-Always) Castle and Beckett travel to sin city and wake up married

Notes: It's not Sin City, but it's close.

Takes place during 4x08 - Heartbreak Hotel. Totally AU.

The sunlight is her first clue that something is amiss. Her room is never this bright. Not since she installed the new blinds and decided to add light-blocking curtains as an extra measure of privacy.

Why is her room so bright? Did she forget to close everything up tightly last night? The last time she had, the nightmares came. She's pretty sure she didn't have nightmares last night. No, she actually slept well last night.

Her feet slide under the sheets experimentally, seeking out the weight of the blanket she keeps at the end of the bed. Had she kicked it off in the middle of the night? She wouldn't mind it now. It's a little chilly in here.

She doesn't find the blanket. The foot she encounters instead is a surprise.

The fact that it's connected to a soft, warm leg is less of a shock, since it'd be a lot weirder to have just a foot in her bed. (Well not her bed, this isn't her bed, she just knows it, but she isn't brave enough yet to look around and see whose bed it could be.) But it doesn't make her feel any better.

She's in bed with someone.

No. No, no. She hasn't had a one night stand in years. Kate Beckett does not do one night stands anymore. Not since the worst of the months after her mother's death, when her entire damn life was turned around and upside down. Kate Beckett is … shit, she's trying to get herself together in hopes that maybe theycan be something once the dust settles with her.

It takes monumental effort, but she tells herself to breathe. Just breathe. Maybe it's not… what it seems.

Experimentally, her foot move higher, leg contorting just a little with the effort, only to stop when it encounters worn cotton instead of warm skin and the gentle dusting of hair. Boxers. He's… okay good, that's promising. She peeks an eye open to survey her own clothing situation, releasing a shaky breath when she sees that she, too, is clothed. Mostly. She's in her camisole and panties, but… it's something.

There's an arm around her waist, a large one. Tanned against the white of the sheets. Hotel sheets?

Atlantic City. She's in Atlantic City. She drove down to help the boys, and when she arrived, they were wearing those ridiculous Elvis costumes. Castle's idea.

Castle.

Oh she knows this arm. She knows this thumb. Those fingers brush against hers every day when he offers her coffee like a kiss.

Okay, what the hell?

A ring?

Her hand scrapes over her face. She's in Atlantic City, in bed with Castle and he's wearing a ring. On his left hand. On his ring finger.

And if the cold against her nose is to be believed, so is she.

Oh shit.

They weren't drunk, she knows that. She doesn't feel hungover at all, for one. She remembers the four of them sharing a single pitcher of beer while they discussed their next move in the case. She'd been about to make herself scarce so the three of them could continue their IBPWOC – try saying that ten times fast – when Castle sent the boys ahead, staying with her instead.

They'd talked, she remembers, seriously talked. She's not even sure what prompted it, the first moment of sharing, but he'd scooted closer in the cushy booth, resting his chin on his hand and keeping his eyes on her. It's possible he never took his eyes off her.

And then somewhere along the way she'd asked about his marriages, about the feeling of impending doom she'd heard him talk about the other day. By then their fingers were brushing against each other, doing a painfully shy dance of hopefulness and longing.

Her hand drops from her face, landing against his with a quiet slap. His thumb twitches under her hand, coming up to curl around hers and draw it closer. The rest of their fingers slot together, rings clinking softly. It's… surprisingly not as terrifying as she'd expected it to be.

Finally feeling daring, she looks around with a practiced eye. This is his room, she's sure. Not as large or luxurious as she would've expected, but even Richard Castle can't get everything on short notice. His bag's on the luggage stand in the corner, and tucked neatly beside it is the overnight bag she keeps in her trunk for emergencies.

They're alone in the room, so that's good. Ryan and Esposito are nowhere to be found. In theory that means nobody's playing a prank on her…

"Mmm, Kate, go back to sleep."

Well at least he knows he's with her. Or he's with her in whatever his slumber is telling him is real.

"Would you ever get married again?"

Oh, that had been her question, hadn't it? Posed between sips of water and nibbling from a basket of fries he'd ordered after finding out she hadn't eaten since her early lunch. He'd flushed and demurred at first, tripping over his words to explain he wouldn't mind, under the right circumstances, with the… right person.

He'd looked straight at her then. Still shy, but purposeful, and somehow she hadn't frozen in fear. Hadn't let terror take over her brain and send her running. She'd just smiled, sliding her hand under his.

It'd been her idea.

Shit, they'd gotten married. Because she'd suggested it. She'd proposed to him in the middle of an Atlantic City casino restaurant, completely sober, completely serious.

"Castle, Castle wake up." Their joined hands wiggle against her belly in her efforts to rouse him. "Castle, we got married last night," she hisses.

"Mhmm," he mumbles, burying his nose deeper into her hair. "Paperwork's being filed today. Too late las' night."

Right. The paperwork. The forms they'd signed and promised to file as soon as possible to make what was a surprisingly tasteful ceremony official. He'd sent it to his lawyer before escorting her back here. To their room.

Oh God, they're married.

It's on the tip of her tongue to ask if it's too late to take it back, but his chest brushes her back when he inhales and her tension somehow eases. The solid wall of him behind her scatters the thousands of questions and objections she has. Instead of "I changed my mind," out comes something else entirely,

"What are we going to tell people?"

A/N: The first four chapters of this have been posted to my tumblr already, so I'm going to be posting them here quickly to get both pages up to speed. I apologize in advance for clogging anyone's alerts!