A/N: Written for the winter hiatus kink meme over at livejournal (which is down at the moment so forgive the lack of the exact prompt this fills). Basically Beckett + removable showerhead = fun times, u kno.

The shiny new key Beckett gave him to her apartment burns a hole in his pocket as Castle knocks on her door for the third time, still with no answer. He knows she's home, she texted him to complain about how chilly her apartment was when she got home from work. He of course interpreted this as an unspoken invitation to come over and warm her up, and so here he is, shuffling from foot to foot, and then finally sliding that shiny new key into its hole and stepping his way into her space like he belongs there.

As he shuts the door behind him, he sees her bag on the floor in the hall, hears the faint white noise of her shower coming from the direction of her bedroom. A grin tugs at the corners of his lips as he realizes why she didn't hear the door, and he immediately begins shedding layers of clothing as he makes his way to where she is. His scarf is unwound and draped over the back of a chair, shoes toed off halfway through the kitchen, jacket tossed onto the couch as an afterthought, and then one hand starts unbuttoning his shirt as the other reaches for her bathroom doorknob and he steps inside and freezes, caught off guard by the sight before him.

He had expected her to be in the shower. Curtain closed, room filled with steam, maybe a suggestive shadowy outline of her insane body to drive him crazy while he finishes undressing, but instead what he sees is a very naked Kate Beckett on the floor of her bathtub, legs spread, right hand gripping the handle of her removable showerhead really, really tightly as she angles it at her own body.

Fuuuuuck.

Her eyes widen as she watches him come in, but instead of stopping, her hips arch up out of the shallow pool of water beneath her, legs tense as she rolls her pelvis into a stream of water that looks anything but gentle. The toes of her flat feet curl as he watches her try to keep her balance in the slippery tub, all the while desperately trying to catch the pressure of the water coming at her relentlessly. She's wet everywhere, slick chest, damp hair (from both sweat and water alike, he thinks), dripping thighs. He doesn't even know where to look.

A soft groan is tugged up from her chest as he drinks her in, and it is this that makes his eyes finally decide to rest on her face.

"Why didn't you call me?" he blurts suddenly, and can see that she immediately assumes he's hurt that she would turn to her showerhead rather than her very, very willing partner, but it's not what he means at all. He kneels down by the side of the tub, shaking his head at her knitted eyebrows. "I would have strapped on that experimental jetpack I ordered off the internet the other day if I had known you were over here doing this."

She rolls her half lidded eyes at him, amused and aroused, a devastating combination to witness.

"I was cold," she breathes out, going for a shrug of her shoulders, but the stream of water moves and she hisses at the new and unexpected contact. "And – " she pants, "the water felt good."

"Yeah it looks like it feels good…"

"Castle."

He cant resist shoving up the sleeve of his shirt, cuffing it haphazardly as he slides his left palm over the knee she has pressed against the side of the tub, his fingers trailing lightly along her wet skin, gliding his way up and down the inside of her thigh. She's so tense, holding her hips at just the right angle, moving them just a little as she instinctually searches for friction that grinding against water just isn't going to give her.

His lips drop to her knee over the edge of the porcelain, kissing her softly there before turning to rest his cheek on it.

"Do you want some help?"

He'd be content just watching her do her thing, but it feels impolite not to ask, and he also really, really just wants to touch her.

Instead of answering, she reaches for him with the hand not wrapped around the showerhead, her slippery fingers sliding against his as she tugs his hand between her legs. The spray is sharp against his knuckles, but it's fleeting, she wants him lower, inside.

They both groan when he feels how completely slick she is, and then he's sliding two fingers into her just the way she likes it and her back bows completely of its own volition.

She swears his name as he pumps his fingers in and out, mindful of not disrupting the careful angle she's arranged, staring at the way she manipulates the water, and then her hips are up up up, chasing after the high just out of her reach as she all but sobs don't stop don't stop don't stop.

He couldn't even if he wanted to, too entranced by how tightly she is controlling her body while on the razor's edge of release. It's mesmerizing. A flickering impulse to slide his thumb up and over her pulses behind his eyelids as he tries to help her finish, he knows that's all she would need to come crashing down, but she's way too into what she's doing for him to interrupt.

So he lets her go. And go and go and go until she's up on her toes and clenching around his fingers tighter than he thinks he's ever felt like this. Her teeth are pressed together hard as her eyes squeeze shut, and then she's shoving away the water and closing her legs around his hands, rubbing herself against her own thighs and panting as she twitches under his touch.

"Warm now?" he asks lowly as he watches her slow grind through the aftershocks of what he can only imagine was an intense as fuck orgasm.

The way she sloppily wipes the sweat off her forehead with the back of one hand is answer enough, but she impulsively leans up to catch his lips, grabbing the back of his head with both hands and inviting him into her mouth to taste just how warm she really is.

"Get in," she growls against his lips as she reaches past him to turn the hot water back on.

He doesn't think he'll ever be cold again.