I sort of… stole this prompt outright from Carto's suggestions for Sandiane Carter and chezchuckles, both of whom have UNBELIEVABLE multi-chapter stories on the prompt. Go read both of them. They're both called Vice.

Set five(ish) years pre-series: Castle's still writing Derrick Storm, Beckett's a hot young Vice cop.

Uncommon Vices

It has been my experience that folks who have no vices have very few virtues.

Abraham Lincoln

Castle half-thinks Patterson wanted to get him mugged. Seriously. "Seedy" would be a compliment for this bar. Cherry is the dirtiest place he's ever been. There are things happening – oh shit there are couples doing things that should definitely get them arrested – but wow. Wow. This is unbelievable. If he doesn't get shot, he is totally putting this place in a book.

He's got his drink and he's settled comfortably at a little booth that's the perfect vantage point; he can see the whole place. The details jump out at him, starkly real: the smoky air, the scuffed floor, the deep red curtains blocking the windows. Tables high and narrow enough to reach someone's hand (or...other things) underneath. The half-smoked cigarette in the ashtray on the table with a faint stain of lipstick on the end. Whoever she was, she left before she was finished with it. But it's set down carefully, not tossed, so she must not have had to run. Maybe it wasn't in panic. Maybe someone came over and whispered something in her ear. An invitation. She would have thought about it. Considered. Then shot the mystery man a sultry half-smile as she set down her cigarette and joined him for - a drink? a dance? - and maybe after a few minutes of letting his hands wander, she tugged him close, traced his neck with her tongue as she leaned in and whispered into his ear Let's go back to your place -

He's staring at the cigarette, the mystery woman rapidly materializing in his mind in a cloud of red lipstick and black stilettos and wide dark eyes, when she speaks.

"That's my seat."

He blinks dazedly for a second, looking up, and there she is.

And wow. Just wow.

She's tall, slim, hauntingly gorgeous, with eyes he can't stop staring into. Short, sex-tousled dark hair. Lips as red as sin. Her dress is short and tight and glittering black, low-necked and short-skirted and so utterly indecent it stops him short.

Wow.

He's not sure if she's a hooker or not. She's unbelievably hot, and she could definitely be one, especially in those tall, sexy shoes that are just begging to slide over his thighs while he thrusts into her (because who wouldn't pay for it with her?) but there's something else there, something different. She's not jaded. She's not looking at him like she's sizing up his wallet. She's eyeing him with a look he can't quite read: irritation, maybe, but there's definitely a hint of amusement in the quirk of that pouty red mouth. She sets her hands on her hips, and he realizes he should probably say something, not just stare. Come on, Rick. You've got more game than this.

"Uh. Sorry. I didn't realize." He grins. "You're welcome to join me, though."

"I guess I'll let it go," she murmurs, sliding into the booth beside him, and he thanks everything that these booths are small and cramped because that means she's pressed against him, flush and warm and bare skin and he gets a look down the front of her dress and shit he officially loves this place.

"So. You come here often?" Not his best, but it's something. Even Bond started somewhere.

"Often enough."

"I'm Rick."

Her lips twitch, like there's a joke he's missing, but she just shrugs. "That's nice for you."

"Aren't you going to tell me your name?" He really should move, give her some room, but he can't help himself. He's mesmerized, drugged by this bewitching young woman with her smoky eyes, her teasing mouth. He wants to kiss her. He wants to slide his hands up over her thighs, edge under the skirt of this flimsy little black dress and make her gasp. He wants to pull her into his lap and suck on the smooth column of her throat until she squirms against him. He wants to drag her into a closet, shove her up against the wall, and push her skirt up her thighs while she wraps her legs around his waist.

"Why do you want to know?"

"I like you." His fingers trail over her arm, and he watches, fascinated, as she takes in a quick breath.

She flicks a sly glance up at him, and yeah, he's definitely interested, but - he can't place it, but something's off. Something. She looks like a hooker, yeah - well, maybe - but there's something - the way she started when he touched her -

Wait.

Her seat. Her seat -

"So you always sit here, huh?"

"Yeah. Until you decided to steal it."

"Gives you a good view of the room, right?"

She shoots him a startled look, clearly trying to figure out how to respond, but it's too late. His eyes go wide. "Wait. Oh my God. You're a cop. Are you a cop?"

"Dammit, shut up." She sighs, grits her teeth. He wants to kiss her. "Yes."

A cop – then she's older than she looks. Has to be. Oh, this is perfect. This is amazing. He's at a dangerous club, drinking good liquor, with this wild, feral, sexy young cop pressed up against him. Best night ever.

"Can I interview you?" Storm could totally do a stint in Vice. Besides. Rick would have no problem interrogating this hot, hot young thing. In his bedroom. Or in the backseat of a limo. Or -

"What? No." She stares at him like he's an idiot. "What the hell?"

"Come on. I'm a writer. I write crime novels. I would love to - "

"Shut up," she hisses. "You need to keep your voice down."

Oh God this smoking cop is working and he cannot handle it and he's torn between needing to ask her a thousand questions about every nuance of her job and needing to rip this dress off of her and worship her body with his mouth.

"Alright. Fine." But if she's working...that makes this all fake, right? So he can...touch her?

Instead of asking permission, he leans in, ghosts his lips over her bare shoulder as he steals one hand over the plane of her stomach. "If you're working, I can help. I can be your cover."

She huffs a short laugh, but it's shaky. He's got her. "Sure you can."

"It's the least I can do for the city I love."

Her fingernails bite sharply into his forearm and he winces, but then she eases up. She bites her lip (shit that is the hottest thing he's ever seen). "Fine. Fine. Just shut up."

That's fine with him.

She arranges herself sort of half-on him, draped easily over his chest and mmm she's so warm and soft, loose and liquid against his body. He slides his hand over her back, and it's all smooth bare skin, the back of her dress cut so low his fingertips actually brush just a hint of the smooth curve of her -

"Watch it," she whispers, and it's meant to be angry but he's too drugged on the heat of her breath on his neck to be anything more than turned on.

"Do you see your guy?" If she came here, to this spot with its clear view, she's here to see something. Safe bet it's a person, right?

"I think - " She shifts, accidentally slipping her knee between his legs and shit his pants are getting tight. "I - wait - no, no no - "

"What?" he chokes out, blind and unaware and not caring about anything beyond the almost-naked woman grinding against his thigh.

"Shit." She looks around frantically, her dark hair whipping over her cheeks. "Shit, he's coming this way - "

"Yeah, I think he might be curious about why you and I are just sitting here, you know. Not having sex."

"Damn it."

He's about to ask if she's got a plan (and damn this police thing is exciting) when she shoves his back against the wall, hard, and as she straddles his lap and rolls her hips against him, her hands sliding under his jacket, he lets out a strangled noise. "What - what - "

"Shut up," she growls into his ear, and his eyes roll back as she leans into him, her soft, tantalizing curves flush against his body, her mouth skirting his jaw. "Just tell me who the bald guy leaves with."

"Why can't you - "

"He's seen me before, would you shut up - "

Her teeth sink into his earlobe and his hips jerk up into hers roughly, his hands tightening against her thighs. He swallows hard, trying to ignore the slow wet trail of her tongue over his neck. Shit. Shit, he has to focus or she's going to climb off his lap -

He blinks. Uh. Bald man. Right. Bald man, bald man bald m-

Her hand slides lower and he gasps, clutching at her wrist. "You - you need to not - "

"Just watch him."

Rick grits his teeth, clenches his fists, and fixes his eyes on the bald guy in the tacky suit near the back of the club. Her lips ghost over his throat softly, so teasing, and he screws his eyes shut because he absolutely cannot deal with this.

He focuses on Baldy, who's talking to two other guys, and surrenders himself to this darkly sexy young woman who seems determined to slowly drive him insane.

The second he chokes out "he left - oh god - left with the tall guy," she leaps off him like she's been burned, and it takes him a second to catch his breath and shit his body is so tight and hot and wanting it's actually physically uncomfortable.

He follows her obediently, staring, wide-eyed and dry-mouthed, as this lithe young sex goddess murmurs something into a radio receiver (where the hell was she hiding that?) before grabbing his arm and pulling him away down the street.

He babbles to keep himself from putting his hands back on her. "What was that? What were you - "

She shoots him a baleful glare, though its effect slightly lessened by the visible flush in her cheeks, the unmistakeable pink spread across her chest. "I can't tell you."

"Come on! Have a heart." He sidles up, steps into her space, lowers his voice suggestively. "If you'd rather discuss it in private, I'd be more than happy to oblige."

She shoots him a halfhearted glare, but he sees the quick flicker of heat in her gaze. Oh, yeah. She's into him. "I can't discuss an ongoing investigation."

"That is so hot."

She glances back, but the door is shut behind them. "Let it go, okay?"

"Let it go? Are you kidding? Oh my god, you - you're a cop, and you can - and holy shit, you have handcuffs, don't you? Please tell me you have handcuffs. And a thigh holster."

The look she gives him is more amused than anything. "It wouldn't even matter if I told you no, would it?"

That's basically a yes. Castle's in heaven. Sexy cop. Handcuffs. Some shadowy mystery of a mission. He doesn't know what exactly she was looking for in that club, who the bald man was, and he really genuinely doesn't care because wow. Huh. He just got sucked into a Vice sting, didn't he? Maybe Storm could walk into a seedy club, find a nubile young plaything to help him do surveillance and let his hands end up -

The cop is staring at him. He clears his throat. "What – mmph."

Before he can get the question out, she's grabbed him, yanked him to herself, and then oh God this smoking hot Vice cop is kissing him hard, her tongue sliding aggressively over his lips as her slim body presses against his and oh that's so hot -

She steps away and it's all he can do not to grab her again. But she just smirks at him, entirely too pleased with herself, and pats his chest.

"That was a thank you."

She moves as if to go, but he catches her wrist, tugging gently. "That's it? Come on. We could go somewhere. Debrief each other."

"Seriously?" She rolls her eyes. "You're going with debrief?"

"I'd be happy to let you debrief me."

She bites her lip and grins, but pulls her hand away. "Look. Just stay away from this place tomorrow, okay? Don't come near it."

Does that mean a sting? Holy shit, is Vice doing a bust?

She must see the excitement on his face, because she sets a hand on his shoulder. "I mean it, okay? If it goes south you might get hurt. Please. Stay away."

"Come on. I don't even know your name. How will I find you?"

"You won't." She turns away and he watches dumbly, staring at the smooth lines of her, the teasing shift of her hips, the long, lovely legs, and who is this gorgeous young woman and he just has so many questions -

She pauses and looks back over her shoulder, the city lights playing over her face, lighting up her eyes, dark and sparkling and full of secrets.

"Go home, Mr. Castle."

And then she's gone.

He goes home, showers quickly to scrub off the smell of sweat and smoke and her, and goes straight to his computer. A scene unfurls under his fingers, a dark, smoky bar, shadowy figures, Derrick Storm getting cozy with a sexy young Vice cop in a flimsy black dress who's too green not to shiver every time he touches her, who pushes his hand between her legs and whispers let's go debrief each other in my car...

It's three in the morning, and he's been typing feverishly for hours, when he suddenly stops.

(Go home, Mr. Castle.)

He never told her his last name.