Written for Porn Battle XII for the prompt clothed sex. Takes place anywhere in the last half of season 3.
The elevator door pings and separates as Castle takes a cautious peek around the hallway of the twelfth precinct's homicide division, scanning the empty floor for any signs of life. It's late, almost midnight on a Wednesday, and the place looks predictably deserted. The guard on duty in the lobby is a fan, and Castle finds it easy enough to gain entrance to the semi fortified building housing the desk of his usual partner in crime, Kate Beckett. (It's amazing what a charming smile and well placed salute will get you). His feet move quietly across the scuffed linoleum, down the well worn path to her workspace, where he is ninety nine percent sure he left his cell phone earlier that evening.
He just can't sleep without his customary game of Angry Birds before bed.
The theme song to Cops echoes through his head as he taps out a beat against his jeans, reaching for the little black phone when he spots it sitting right where he vaguely remembers setting it down. A stray piece of paper catches on the side of his finger, making him flinch as he yanks it back and notices that Beckett's desk is a little bit more mussed than she usually leaves it at the end of the day. Papers are strewn rather than stacked, pens left in the creases of a file instead of tucked neatly away in her drawer. Her computer monitor is still on too, and her jacket is draped over the back of her chair. Castle's ears prick up as he hears a noise coming from upstairs, muffled but definitely there. He freezes on the spot, simultaneously nervous about being caught in the precinct after hours, and wondering what he will do if he has accidentally caught someone else there at the same time. Not for the first time, he wishes Beckett would let him carry a gun (or at least some kind of cool taser or something). Silence buzzes in his ears as he strains to listen for anything out of the ordinary, and he nearly jumps when he hears a loud, female, grunt coming from just up the stairs. His eyes flick from Beckett's left behind jacket to the steps exactly once before he pockets his phone and dashes to the stairs as quickly and quietly as he is able.
With worst case scenarios and visions of daring rescues pinging themselves around his brain at the speed only a best selling novelist can achieve, Castle rounds the top of the staircase to a scene more likely to come out of his secret fantasies than his murder mystery plotlines. He has caught someone else lurking at an inappropriate hour of the night, has caught her, but as he watches her throw punch after punch at the heavy bag dangling from the ceiling in the middle of the sparse in-house gym, he's not quite sure what to do about it.
He could leave, of course. Could just back his way out the way that he came in and leave her there to work out whatever frustrations have her beating the shit out of an inanimate object at midnight on a weekday, but he's Richard Castle, and he just doesn't know when to leave things alone.
So instead of heading back down the stairs, back out to his car, and home to his slumbering family, Castle takes about a dozen steps into the room until he is close enough to reach out and touch her. She's so focused on hitting that bag, on landing punch after punch after punch on the little red X she has fashioned on its exterior, that she has clearly not heard him approach. A twinge of satisfaction runs through his gut at being able to sneak up on her, the usually hyper aware detective, but his pleasure turns to intrigue as his eyes truly take in the sight before him. Beckett's long hair is tied back into a messy bun atop her head, but loose tendrils have worked their way out to stick to the back of her sweaty neck, making her look wild from behind. Her shoulders and lower back are bared from beneath a tight black sports bra (and even tighter yoga pants), leaving her almost as exposed as he's ever seen her, and Castle looks. He feels a bit outside of himself as he quietly reaches out to tap her shoulder, feeling too much like a voyeur standing behind her secretly as she continues to throw herself at the bag. Just as his fingers make contact with her hot, clammy skin, Castle feels her tense, feels her bare hand come up to cover his own, feels the ground shift nauseatingly under his feet as he is suddenly looking up at the white tiles of the ceiling and then oof, all of the air is being knocked out of his lungs and his back has somehow connected with the deceivingly hard gym floor.
"Beck–" he starts to moan as he feels his back ache and shoulders burn as his arms are forced above his head and against the ground. He is well and truly pinned in about three seconds flat. A red faced Beckett pops into his eyeline as he tries and fails to take a breath, and she looks pissed.
"What. The. Hell. Castle?" she says, annunciating every word like she's talking to a three year old. She's also panting, which Castle takes immediate note of as her heaving chest peeks out at the edge of his peripheral vision. His eyes shoot skyward immediately as he tries to avoid an inappropriate eyeful, and then flick guiltily back to her own green gaze. She's not letting go of his hands.
As much as he would like to explain himself, Castle cannot seem to gather enough air to breathe, let alone speak, so he struggles weakly underneath her weight, trying to express with his eyes that he really, really did not mean to sneak up on her and scare her half to death. As they stare at each other, her brows knit together, but then smooth out dangerously as her eyes narrow to slits and her mouth is suddenly right next to his ear. His chest burns with need as he feels her hot breath there.
"Were you watching me Castle?" she asks, tone so dangerously low that he's not altogether sure what has just happened. He thinks he might pass out. The implication of her words serve to take his mind off of breathing long enough to allow his body to pull in a mouthful of much needed oxygen, his fingers flex under the tight grip she has on his wrists in response to her question, but he doesn't answer, can't answer (can hardly remember the question with her so glaringly close to every place on his body he's ever wanted her).
She moves her head back up then, like a snake, letting her lower body relax to lie fully against his, no longer keeping that inch of space between them. This is breaking The Rules so completely that he cannot help the involuntary roll of his hips up against hers at the contact. Her right eyebrow rises in that way that it usually does when she is amused, and he feels his heart start pounding harder for each second that she does not move away.
She doesn't though, move away, instead returning his body's gesture with a very deliberate one of her own. He can see it in her eyes that she knows exactly what she is doing to him, can see that she has come a bit unhinged, whether it be from the temptation of their current situation, or the time of night, or the extremely rough case they've been working that they just can't seem to close, but she's playing with fire. She's playing with him, and she looks feral.
Their eyes lock as she licks her lips and rolls her hips again, and then suddenly one of her hands is releasing his captured wrist, and the other is sliding her palm flat against his and her fingers in between the spaces his leave blank. The linking of their fingers is as much of an act of consent as any spoken word, and they both take it as such as his free hand flies to her side and her mouth hangs open as they grind her hips down together in a tight little circle right over his zipper.
Once she starts moving, it's fast. She's already so worked up, so tight and tense, that it doesn't take much at all. Castle's hand is leaving fingerprints on the bare skin above her pants, helping her move and keeping her from going anywhere all at the same time. She needs this, and he knows she needs this, and he is all too happy to oblige.
Castle watches her face as her breath starts to hitch, as she leans forward a little bit more, bracing herself against his chest with one hand and catching just the right rhythm against him. He's got an amazing view of her cleavage from where he's laying, and she watches as he lets his eyes wander down down down. When he picks her eyes back up they are unfocused and dilated, watching him as much as he is watching her. She almost smiles then, he thinks, he can see it ghost across her face, like she's having fun, and it makes a heavy groan stick in his own throat. He's wanted to see her like this for so long, he can hardly believe this is happening. As she continues to move, driving him crazy one shift at a time, his hand aches to move to her front, to somewhere he can feel the slippery heat of her, but he doesn't want to overstep. Instead he moves it down to cup her backside, to help the roll of her hips keep up her frantic rhythm as she starts making these noises that make him want to flip her over and press her into the floor. Over and over she rocks against him, and he is captivated.
He can tell she's close when she sucks her bottom lip into her mouth and bites down. It's her classic tell, his Kate Beckett has a major oral fixation that he's not altogether sure she's even aware she has. Needing to be closer, Castle lurches upward and threads his hand into her hair and behind her neck, pulling her flush against him as she rubs. He holds them cheek-to-cheek with his palm, whispering things to her that set his own blood on fire. The sound of his voice while she's so on edge sends a violent shiver through her entire body, making her legs clench around his middle and her back arch sharply as she clutches herself to him, gasping loudly.
He wishes he could see her face, watch her come apart around him, but he can feel her shudder, hear her pleasurable sob as all the tension leaves her body in one flash of heat. She stills after a few moments, resting her forehead against his shoulder until she regains her breath, and then hesitantly pulls herself back to look at him with hooded eyes. More of her hair has fallen out of her ponytail, sticking to the sides of her flushed cheeks, mingling with Castle's circling thumb. She looks like she doesn't know whether to thank him or run.
Ever her knight in shining armor (on those rare occasion when she actually lets him), Castle flashes her a winning smile and tries to ease her uncertainty the best way he knows how. "I feel so used, you didn't even get me naked," he jokes lightly, eyes sparkling, and then she laughs, burying her face into his neck because he's still Castle and she's still Beckett and this was going to happen eventually anyway.
He can feel her lips curve against the bare skin of his neck as she smiles into his skin, and then she's moving back again, holding his gaze until she leans forward to pull a kiss from his lips that does nothing but make him want her to do it again and again and again. "That can be arranged, Mr. Castle," she says as she takes his face between her palms.
He's grinning so hard he's not sure the whole thing can fit between her impossibly small hands.