From a prompt on the castlefanficprompts tumblr: Season 1/2. Beckett offers up a blowjob in a dare/bet. Maybe over a game of poker, him shutting up for a week, etc. Set s1, between Nanny McDead and Hedgefund Homeboys.

getting down – betting terminology that refers to the action of placing a wager on a game

Beckett's all business as they walk out of interrogation, but the mask drops from her face as she closes the door behind them. Her eyes are a storm of roiling clouds, her jaw set in a way that emphasizes her cheekbones.

She's terrifying and entirely sexy.

She grabs his arm tight enough that he winces and swings him around into observation. "When will you ever learn to keep your mouth shut?"

"He was lying!"

"What part of 'observation only' is so hard for you to comprehend?"

"Oh, come on, I got him to confess, you should be thanking me."

It is absolutely the wrong thing to say but he realizes that a moment too late as the storm in her eyes turns decidedly terrifying and not at all sexy anymore.

Well, okay, maybe still a little sexy.

"You think that we're an amusement park that you can just come into and toy around at but when you leave, we still have a murder to solve. This is my career, this is my life, and when I tell you to sit down and shut up, I expect you to sit the hell down and shut the hell up."

He needs to just start a voice recording on his phone every day to capture all of the choice things she says. Because that little speech is definitely going in the book.

"Okay?" she barks; apparently, he was quiet a beat too long.

"Yes, okay," he squeaks out quickly.

Her eyes narrow unbelievingly and he stands up straight, tries to smile convincingly and after a handful of seconds, she turns on a heel to leave the room.

"Bet you I could though," he calls out as her hand touches the doorknob. "Bet I could keep my mouth shut. I'll do it for a whole week."

She laughs as she turns to face him, her completely disbelieving scoff emboldening his resolve.

"I mean it, bet me. For one week, I will just observe in interrogation. I can still talk outside of it, still participate in building theories but when you tell me to shut up, I will."

"I'd be saying that a lot."

"I know."

She stares him down but he doesn't waver and unease washes over her face. "You're serious?"

"If you win, I'll buy you lunch every day for the next year."

"Assuming you stay a year," she mutters.

"Fine then, every day for the time that I'm here."

"And I get to pick the place." She leaves no room for argument on that point and he nods his assent. "And what do you get?"

He hesitates for half a second. "A blowjob."

She huffs a laugh. "Sure, Castle, I'll give you a blowjob." Her words are saturated with sarcasm, punctuated with a roll of her eyes.

"Scared you'll lose?"

She crosses her arms over her chest. "No." She means it. She really doesn't think that he can do it. But oh, with that prize waiting at the end, Kate Beckett will find out firsthand how determined he can be.

"Then it's a bet." He holds his hand out and she takes it, one firm pump of their hands to seal the deal.

He is an idiot, a world class moron.

The guy sitting across from Beckett is relaxed, answers all her questions with ease but Castle can tell, he knows that the guy is a slimeball. He may not have committed the murder, but he sure as hell knows who did. Not that he's giving up that information with all of the doubletalk he's giving the detective.

"And you knew Miss Diaz?"

"Oh, yeah, she was a sweet girl."

Ugh, the audacity of this guy. Castle can hear it in the sleazy way he says it that if he didn't know her in the biblical sense, he certainly wanted to.

"You two spend a lot of time together?"

He pauses for the briefest of moments. "Yeah, some."

Castle shifts forward, a groan starting in his throat and Beckett shoots him a look, equal parts chastising and triumphant and he sits back, the sound falling to ash in his mouth.

"When was the last time you saw her?"

The guy shrugs. "Two weeks ago?"

Lie!

The word wants to escape, he barely stops himself from yelling it and he knows, he has to get out of here. He stands and slips through the door, slipping into interrogation to watch her tear the jerk's alibi apart, the man giving her a name from trembling lips as he realizes he has no other option.

"Deli around the corner, turkey on rye, lettuce, tomato, no mayo," she tells him as they exit their respective rooms into the hallway.

"Wait, what?"

"My lunch order, since you just lost."

"I didn't say anything!"

"You got up and left before you could, that's cheating." She sits at her desk, stabs at her keyboard to wake up her computer.

"Wait, no," he bargains, dropping to the chair beside her desk that he's quickly starting to think of as his. "The deal was, I couldn't talk, we didn't specify beyond that. I did what I had to to keep up my end of it."

Her eyes are still fixed on her computer screen but she chews on the inside of her cheek, contemplating. "Okay," she turns toward him and he leans forward. "I will give this to you this one time but for the rest of the week, you have to stay in that room and stay quiet. If you leave or if you don't even come in, it's cheating and you forfeit. Deal?" She holds a hand out and he quickly takes it, shaking vigorously.

"Deal."

He's pretty sure she's hiring actors to play the most frustrating suspects ever.

There's the guy that leaves the door wide open for sarcastic comments that he would love to interject. There's the charmer that hits on her the whole time and it's not so much that he wants to say something more than he'd just like to laugh at him for even trying to woo Kate Beckett. Yeah right, buddy, she is way out of your league. There's the woman that he is definitely using to base a character off of, if only he could ask her a few questions, get into her head a little more. He almost follows her out in the hall to get some choice soundbites but he's pretty sure Beckett would call that cheating, too.

She never comments on how quiet he is, how well he's doing. But every day she looks a little more tense, every interrogation that he makes it through puts her a little more on edge.

The last day is a cakewalk; her only interrogation is with a nervous young woman that cracks after two questions, spilling all of her secrets across the metal table. He follows her out of the room like normal, they walk over to her desk and she pulls a form out of her drawer to fill out while he checks his email.

Usually at this point, he leaves because the paperwork is the most boring part of this. But not today. He watches her out of the corner of his eye, admires her slender fingers as they grasp the pen, smiles at the wrinkle between her eyes that forms when she's concentrating. He takes a good, long look at her mouth, the way her lips move subtly as she narrates what she's writing. The tip of her tongue peeks out for a moment and he wets his own lips unconsciously.

She sets her pen down and pins him in place with her eyes. "Case is closed, Castle. Don't you have somewhere to be?"

"Nope, just waiting on you."

"You're gonna watch me fill out forms?"

He shrugs. "I can play a game on my phone."

"Until I go home?"

"But Beckett, it's been a week." He leaves it at that, raises an eyebrow at her.

She sighs. "You're really going through with this?"

There's something in her tone that makes him pause, a fragile edge to her words that he actually doesn't want to press against. He won't make her go through with this, not really. Besides, he never thought that she'd agree to it in the first place so if she's backing out, he'll let her.

He's not an asshole.

She picks up the pen and refocuses on her form and he prepares to leave her to it and never speak of this again.

He rises from the chair, slides his coat on and just as he secures the last button, she murmurs, "Be at my place at 8."

He stares at her in shock for a moment, unsure that she actually spoke at all. She cuts her eyes to him, gives him a look that clearly indicates he shouldn't be here anymore and he hustles to the elevator, a wide grin on his face the whole ride down.

He knocks on her door at 7:55 and mostly expects her to not even answer but the door swings open a moment later to reveal Beckett clad in leggings and an overlarge shirt, the neckline falling off one side to display an invitingly creamy shoulder. He clears his throat to speak, to tell her again that she doesn't really have to do this but she holds up a hand to stop him and then uses that same hand to grab a fistful of his sweater and haul him into her mostly darkened apartment.

There are candles set about randomly, a few table lamps turned on low and the whole place is washed in a warm, orange glow. He hears music playing, something soft and melodic and it hits him. Beckett's setting a mood.

She slides the coat from his shoulders, pressing her breasts to his chest to reach behind him and catch it before it can hit the floor and turns to lay it over the back of a chair. She turns back, looking up at him through her eyelashes and how had he never realized how much shorter than him she was? She places her hands gently on his waist and turns him until she's backing him across the room. She shoots glances at him as they move, her look so soft and vulnerable that he tries to open his mouth to protest again. But then the backs of his legs hit the sofa and he's sinking down onto the cushion as she sinks to her knees between his legs and her hands are unbuckling his belt, unfastening his pants and, and…this whole thing is way out of control.

He places his hands over hers to stop the work of her fingers against his zipper, has to swallow hard against the rush of sensation.

"Becket, I was being an ass, you don't have to…" He says it on a rush, breathless at the end but she smiles at him.

"A bet's a bet, Castle."

"Yeah, but-"

"Shut up."

"I only had to do that while the bet was on and it's over now."

"The way I understand it," she starts, rising up until one knee can press into the sofa next to him and she leans in until her face is a fraction of an inch from his, "a bet's not over until payment is received. So, shut. Up."

She pops the "p" at the end, her lips pouting to form the sound and he swallows again, nodding quickly and she smirks, pride and power taking over her face. She runs her hand down his sweater as she positions herself, making swift work of his zipper and curling her fingers in his waistband. He lifts his hips obediently and she pulls his pants and boxers down in one go, extracts one foot from a pant leg so she can spread him wide. Her eyes widen at the sight of him and it's his turn to smirk but it's wiped clean from his face as she trails her fingers up the inside of his thigh. She takes him loosely in her hand and his breath exhales on a stutter.

She's barely touched him and he's pretty sure that this experience is going to kill him.

She strokes lightly, barely there touches that are maddening but her fist grows tighter as she moves up and down and soon he's enveloped in her hand and she's rubbing him base to tip, sending his nerve endings on overdrive. She slows her movements as his breathing becomes faster and then she leans in, breathes over his tip and just that, her breath, is enough to have his hips twitch. She lowers her head and finally puts her mouth on him, placing the flat of her tongue to his base and licking a solid line up the underside of his cock.

He moans low in his throat as his head falls back and he feels her smile against him before her tongue swirls over his tip and then before he can react, he's surrounded by the velvet heat of her mouth. He lifts his head and forces his eyes open because he is not going to miss this. She thrusts shallowly, taking as much of him as she can, each movement of her head taking him deeper than the last. She withdraws from around him but he barely has time to miss the feel of her as she immediately laps at him, swipes of her tongue over the painfully rigid length of him. She licks him thoroughly and then places her hand at his base, positioning her mouth at his tip.

She looks up at him, not a coy look through her eyelashes but making solid eye contact as she takes him in again. She does it slowly but steadily, her tongue moving languidly across every inch she encounters until he feels himself hit the back of her throat.

And then she breathes out and takes the whole of him in and it is the most exquisite thing he has ever experienced.

And then she moves, pulling out to thrust him into her mouth, sucking every time she pulls her head back. He's mesmerized by the bob of her head, by the lightning bolts of pleasure that accompany her movements and he just. Cannot believe. That this. Is happening. It's everything he has to keep breathing, stay in this moment when it feels as though he's a ghost, hovering over something unbelievable.

She takes a breath and takes him deep in her throat again without warning; this time he groans loudly, can't stop the "Fuck, Beckett" from escaping his mouth along with it. She pulls off of him in one long suck, his cock parting from her lips with a soft pop.

"I know, I talked, I'm sorry," he pants, "Just…don't stop doing that."

She watches him as she rises up on her knees, her skin flushed, her lips glistening and swollen and she fists her hands in his sweater to tug him towards her, capturing his mouth with hers. His hands rise to cup her face, kissing her back, opening to the intrusion of her tongue in his mouth, giving back as good as he gets. He shivers as she moans when he sucks her bottom lip into his mouth, nibbles at the flesh that's swollen from pleasuring him.

He wants to haul her up to straddle his lap, strip her of her clothing and bury himself deep between her legs. But almost as if she knows what he's thinking, she draws back, dropping back to his crotch and placing opened mouth kisses up the length of his erection.

"You don't have to be quiet," she tells him between laying her mouth on his quivering flesh, "Not if you're going to say my name like that."

She drops her eyes from his and focuses her attention to her task at hand but it's at that moment that he finally realizes that she wants this just as much as he does. He's been enjoying himself this whole time, of course, but he's had an underlying current of thinking that she was doing this because of the bet, that she would never do this for any reason other than that.

But the pleasure she got from him just choking out her name was enough to have her kissing him and if she wants to hear it, he'll let her. She easily pulls moans from his throat as she continues to take him into hers. She finds a rhythm though he can't seem to figure out the pattern, he's just pulled along for the ride. He slides a hand in her hair, his fingers grasping her short locks loosely, not directing, just needing an anchor point in the sea of lust she's drowning him in.

His touch has her humming while her lips are firmly around him and his hips jerk, entirely of his own volition and he immediately feels shameful. He's never been that guy, never one to shove himself into a woman's mouth and especially so tonight. Not that he needs to; she's certainly got this under control. She shoots him a glare and he does his best to look apologetic. She plants a hand at his hipbone, pressing down to clearly indicate that he shouldn't move and then she redoubles her efforts, her head bobbing at an astonishing rate as she brings to him to the razor's edge of pleasure. He rides there as long as he can, breathing hard and soaking up every detail he can until he knows he can't hold on any longer.

"Beckett, I'm gonna," he manages to get out and she slides him deep again. And then she swallows and swallows again and his orgasm rips through him, her name mixed somewhere in his earth quaking groan. He collapses against the back of her sofa, his head falling back and his eyes dropping closed. His mind is spinning with phrases and images and he wants desperately to write, to convert every feeling of this experience into words. He's pretty sure she would have shot him if he had brought his laptop along though. Besides, there is no way that he is going to be able to forget that.

As his breathing evens and he comes back to himself, he's aware of a warm weight on his thigh and a soothing brush against his skin. He raises his head to find her cheek resting on his leg, her fingers rubbing aimlessly while she regards him with soft eyes. Kate Beckett is watching him come down from a post-orgasm haze. Post an orgasm that she gave him with her talented mouth.

He is absolutely positive that he has to be dreaming.

She shifts back to gather his clothes, tapping on his ankle to indicate that he should lift his leg so she can slide his pants back on and for a second, he considers being contrary, considers kicking his pants off the ankle they're still hooked around, pulling his sweater over his head and tossing it across the room and then doing the same with that huge shirt she has on. But then the rational part of his brain kicks in and he knows that he shouldn't push it, he should let this be what it was – amazing – and save what might be for another time.

Because with the way she's been looking at him, there will be another time. A time when he'll get to kiss her properly, know the feel of her skin under his lips, the taste of her over his tongue. A time when he will gladly be a notch in her bedpost.

He places his foot obediently in the pant leg and allows her to rise up on her knees, bringing the clothing up to his and tugging the fabric to indicate that he needs to stand to complete this task. But instead of complying, he runs his fingers over her cheek, down her jaw, slides his hand to the base of her skull, cupping the bone softly as he brings his forehead to hers to rest for a moment. Her breath hitches at his touch but she doesn't flinch, doesn't try to get away; she not only lets him but her eyes close and she presses her forehead to his.

He moves to ghost his lips over her cheek, breathes "Thank you," against her skin and she releases an unsteady exhale.

He stands then but she stays there kneeling on the floor for another moment, the waist band of his pants still clutched in her hands so tight that her knuckles are white. She takes another breath, steady this time and shifts to stand, completely avoids his eyes as she slips his boxers into place, fastens his pants and buckles his belt. She smooths his sweater down, the knit itchy on his overheated skin but he resists the urge to squirm, not when her hands are running down his chest.

When she seems content that he's presentable again, she takes his hand, and the intimacy of the simple act almost takes him out at the knees. But she's pulling him forward, towards his coat and the door and while he doesn't want to leave, he'll follow her anywhere so he stumbles after her.

She holds his coat out for him to slip his arms into but he shakes his head, plucks it from her fingers to fold it over his arm and takes her hand again for the three step walk to the front door. He wants every moment he can get of her right now, wants to learn this softer Beckett. She still won't meet his eyes but they're not completely downcast and what he can see in them is hesitance, not regret. He thinks that she doesn't want him to leave as much as he doesn't want to go and he again considers laying his lips to hers and then letting her lead the way to her bedroom.

But then she's dropping his hand and reaching past him to open the door, and he wants to say something, wants to protest, wants to drop in front of her and beg her to not send him away but he finds that he can't, doesn't have the heart to break this silent bubble and the warm contentment that he thinks they both feel right now. So he dips his head to brush another kiss to her cheek and backs out of the door, catching her eyes and offering a smile.

The last thing he sees as she closes the door is the wide smile she gives in return and the sparkle in her evergreen eyes.