Title: A New Kind of Sleepwalking

Summary: Katherine Beckett is a very vivid dreamer…

Rating: If you have to wonder, you clearly don't know me. M of course!

Disclaimer: Still don't own these guys. All I own is this scene, because apparently my brain is filled with nothing but smut, smut, smut, smut, smut. Not that I'm complaining…

Author's Note: I thought this up last night in bed as I faked sleep so my insomniac of a brother wouldn't bug me. For some reason, he's gotten it into his head that if he can't sleep, I can't sleep, and if he senses I'm even half-awake he tries to rope me into a late-night game of Jenga or something.

Castle bends down to pick up a glass someone had dropped when he hears the slight moan emanating from his bedroom. Frowning, because he's pretty sure that everyone left the party a while ago – the only reason Lanie and Esposito took so long to leave was because neither of them was in any fit condition to drive, and so had to call a cab and wait.

When he hears another moan, however, Castle knows that he's not imagining things. Someone is still here.

Quietly, he makes his way into his bedroom and looks in. He's just grateful that he got most of the mess cleaned up, because he doesn't want whoever it is to wake up to a trashed party and freak out. He wonders idly if he should get a glass of warm water in case it's Ryan, but then the person moans again and he knows exactly who it is.

"Castle…"

His heart nearly stops.

It's Beckett. Beckett, who he thought had left hours ago (without saying goodbye), is lying spread eagled on his bed. Asleep. Moaning his name.

Wait – moaning his name?

He can't have heard her properly.

"Castle…" But then she moans it again, and this time, there's definite need in her voice. Maybe even desperation.

Trying to calm his breathing, Castle makes his way over to her and sits gingerly on the edge of the bed. Gently, he places a hand on each shoulder and tries to shake Beckett awake. He really doesn't want to resort to dumping water on her face or something.

Beckett stirs, and at first he thinks he's succeeded, but then she rolls her hips and groans. "Just like that…" She whispers huskily.

Several thoughts rapidly flit through Castle's brain. One, Beckett must have had too much to drink and either fallen asleep, or decided to nap to take the edge off her drunkenness. Two, she is clearly dreaming right now. Three, she's dreaming about him.

His jeans suddenly feel way too tight.

Then Beckett gasps a little, and Castle quickly turns his attention back to her. He has to wake her up, stop this before she does something she's going to be embarrassed about once she wakes up. He's immensely grateful she didn't do this while party was still going on, or they'd really have a situation on their hands.

"Beckett…" He whispers, shaking her gently again.

She grabs his wrists with surprisingly agility and strength given that she's asleep, and snakes her hands up his arms to cup his face for a moment before settling on his collar.

"Clothes… you're not usually wearing clothes…" She mumbles, confused. Her eyes are still firmly closed.

Usually? As in, she's had this kind of dream before?

Okay, now Castle has two hard problems to deal with.

Beckett's working to undo his buttons now, and he has a feeling that her fumbling is from haste, and not from any coordination problems. How someone could be so dexterous while they're asleep, he has no idea.

"Look, Beckett, we really have to–" Castle's cut off by Beckett sitting up and pressing her lips to his. She slides her tongue along his bottom lip, nibbling at the corners of his mouth, begging him for access.

It's probably one of the more idiotic ideas he's had (and he's had plenty of bad, dumb, and plain stupid ideas), but he kisses her back. A groan escapes him as their tongues dance, the passion rising with every passing second. She's so talented, and she tastes so sweet, he never wants the kiss to end.

When they finally break apart, Castle realizes that Beckett has somehow managed to not only rid him of his shirt, but pin him beneath her on the bed. She leans forward, her unbearably silky hair draping his chest, and puts that sensuous mouth of hers right next to his ear.

Her breath his hot, but her words are burning. "I want you." She whispers, and her voice is so damn sexy that a younger man would have lost it there and then.

Fortunately, Castle has just enough experience and willpower to hang on. Beckett rises up on top of him so that she's balancing on her hands, and he immediately misses the heat and feel of her body pressed against him.

He knows he's damned to Hell for this, because Beckett will surely kill him once she's awake, but he can't help himself. A few dozen fantasies are scrolling through his brain as he rises up to meet her, placing his hands on her waist and claiming her lips in a fierce kiss.

She moans, her hands leaving trails of tingling fire as she runs them over his chest, shoulders, and arms. He begins to ravish her neck, peeling off her dress as he goes, planting a kiss on every bit of skin he exposes. Beckett arches her back, gasping and groaning. He is the player and she is the instrument, his mouth working her as surely as a member of the orchestra works their violin or piano.

It takes a moment for her words to penetrate the sheer fog of lust clouding his brain, but when they do it makes him take pause.

"The door… Castle… you left the door open." She manages to get out between moans.

Realizing his error, and knowing that if Mother or Alexis sees them he's never going to hear the end of it (actually, Alexis might need therapy), he disengages himself from the goddess in his arms and hurries to the bedroom door, closing and locking it.

It's only as he turns that he realizes that there is no way Beckett could have known he left the door open. Unless…

He turns and Beckett is sitting there, luscious body spread out like a four-course meal for a starving man, a foxy smile on her lips and her onyx eyes wide open. Her grin widens when she sees his expression.

"You're not… you are… but then…" Castle's circuits appeared to have been fried. Beckett just sits there, wearing nothing but a bra that leaves very little to the imagination (dear God, her breasts are practically spilling out of it) and a matching thong.

"Honestly, Castle, you thought I had sleep sex?" Beckett's mouth is twitching, laughter threatening to spill out.

"Well, no, I mean… I wasn't sure, but then… you started it!" He finally ends lamely.

Beckett really does laugh this time. Feeling a little bold, Castle walks back over to the bed and climbs on, straddling her. Beckett grins up at him, fire flashing in her eyes.

"You know that you tricked me, Detective. You played me." Castle admonishes teasingly.

"You're so easy." Beckett gives a very un-Beckett-like giggle.

Her fingers begin to play with the waistband of his pants, and Castle struggles to string a series of words into a sentence. "You know you could have just asked." He says.

"But where would the fun be in that?" Beckett muses, undoing his pants with an expert grace.

"Do you actually… you know…" Castle helps her rid himself of his pants and gets to work on her bra clasp.

"More than I wanted to admit." Beckett gasps. The bra comes off and Castle immediately attaches his mouth to her breasts, making her writhe beneath him. "Oh, Castle… oh God… Please…"

"Were you talking to me or God? It can't be both." Castle teases. Beckett shoots him a glare, but its effect is softened by the slight curl of her lip that he knows means she's fighting back a smile.

Then they're diving for each other again, and for a few minutes no one says anything as they focus all their energies on driving each other crazy, pushing one another towards that brink.

"Rick…" It's more of a breath, a whispered prayer, but it turns him on like nothing else. Hearing her say his name like that, crossing that border of intimacy.

Fumbling, he managed to extract a condom from their hiding place in a drawer, rolling it over himself as Beckett continued to drive him nuts with her mouth and hands. She lay back down on the bed and he positioned himself over her, watching her face carefully as he slid in.

"God, Kate… you're so tight!" He hissed. She bucked her hips involuntarily, her face flushed and head tipped back.

"Rick, please, Rick… I need you…" Those words are all it takes. He begins thrusting into her, and soon they're moving in a frenzied rhythm, drawing closer and closer to that edge.

He can't hold on much longer; she's so warm, so tight, so hot all for him, and he's wanted this for so long, but he wants to take her with him. He slips a hand in between them and plays with her clit.

She screams – Detective Katherine Beckett, buttoned-up by-the-book star of the 12th Precinct, is screaming his name. It sends him over the edge, and they're flying together, ecstasy and euphoria coursing through their veins, draining their energy and refilling them with something else, something more.

He collapses on top of her, sated but exhausted. For a moment she's too full of bliss to say anything, but then she stirs beneath him.

"Castle… you're restricting my breathing…"

He immediately rolls off of her, but takes her with him, so that her head is resting on her chest and his arm is wrapped around her waist. He thinks she'll object but she doesn't, snuggling in closer instead. His hand draws lazy patterns on her back, eventually writing words. He's pretty sure there's something Freudian about that, but he doesn't dwell on it. He's got the most beautiful woman in the world lying naked in his arms, and he'd much rather focus on that.

"I love you."

The words startle him so much his heart gives a jump.

"What?"

"That's what you're writing on my back." Beckett explains, her warm breath dancing across his skin and making it tingle.

Castle's hand stops moving and he almost forgets to breathe, terrified about how she'll react to this.

Beckett takes a deep breath, like an Olympic swimmer preparing for a dive, and speaks. "I love you, too."

Castle's heart remembers it has a job to do and begins pumping at a breakneck speed. He raises himself up a little so that he can look at her face. Beckett props herself up on an elbow, so now they're staring into each other's eyes, and he can see all the pain, all the hurt, all the fear, and all the love shining out at him from those deep mahogany depths.

Sensing she still isn't finished, Castle waits patiently. After a moment, Beckett speaks.

"I remember everything." Her voice cracks, but he doesn't need to ask her what she means. Instead, he draws her up into his arms, holding her to him and kissing her slowly and deeply.

He strokes her cheek with his thumb. "I know."

Beckett laughs, although it's a little choked. "Of course you do." She says ruefully before settling back down, her head on his shoulder.

Her hair is so silky and just begging to be touched, so he begins to stroke it, running his fingers through it. He can feel her smile against his neck.

After a few minutes he can feel her getting sleepy. He's starting the journey into slumber as well, his hand movements becoming slower as his lids droop.

"Castle…" Her voice is surprisingly small. It's almost like she's pleading with him.

"Yes, love?" He whispers.

"Promise me you'll be there when I wake up." Beckett whispers. He briefly wonders how many times she's dreamed this, imagined it happening, only to wake up to a cold and empty bed.

"I'll be here." He whispers comfortingly. "Always."