prompt: she thinks all day long about fucking him. as he leaves for the night, she gives him evidence of that to hold him over until she can be with him.

He needs to stop doing this.

Castle's wearing that shirt. The blue one, the one that makes his eyes absolutely piercing. And normally Kate can handle it; she spent four years keeping her hands off him, after all. But he's been gone for a week on a book tour, and when he walked into the precinct this morning in that blue shirt, smiling, that secretive smile he saves just for her, it took all her self-control to keep from pushing him into the supply closet and giving him a welcome home he'd really, really enjoy.

It's been a torturous day. A day of sitting across a desk from him, pretending to work, staring at the line of his jaw, thinking about straddling his lap and unbuttoning his shirt and sliding her hands under it. He looks good. He has no right to look this good. Not when the only relief she's gotten the entire week was the phone sex they had a few nights ago. She didn't mean to do it, but she missed him, and when he called late that night, his voice was so low and rough, and she was so tired and wound up that her filter just vanished. When he asked What are you wearing, she actually started describing her underwear. And then before she knew it, her fingers were between her legs and she was whimpering as he growled dirty words through the phone.

…and thinking about it right now is not helping.

He's smirking at her – oh dammit, her face is hot – and he's smug, like he knows, he knows exactly what she's remembering. He doesn't even have the decency to look uncomfortable; he's laughing at her, laughing, because she's sitting at her desk flushed and aroused and oh, fuck it. She's horny.

"You doing okay there, Detective? You look a little warm."

She glares at him and he just grins at her. He drums his fingers on her desk and that's even worse. Because he has big hands. Long, thick, strong fingers. And she's spent a week wanting them inside her because hers just aren't the same.

"It's five, Castle. Why don't you head home? Nothing going on here."

He can hear her subtext (I'll leave early) and nods. There's subtext in his grin, too. We have a week to catch up on. He stands up and heads for the elevator, and she bites her lip, looks down, and –

"Castle."

He pauses in the hallway, surprised, as she grabs his hand and yanks him into the closest empty observation room. Doesn't even flip on the lights.

She slams the lock behind her, flicks open the button of her pants and drags the zipper down, and shoves his hand between her legs, where she's soaked through her underwear.

Castle chokes, his fingers curling involuntarily, and she gasps, arching into him, fuck, fuck this is what she's been –

Voices outside. Shit.

She pushes him away, re-dressing herself hastily, her hands shaking more than they should. They slip out the door quickly.
Neither says a word until he steps in the elevator, hands in his pockets, his ears still red. The doors are about to close.

"Castle?" She folds her arms over her chest. "I missed you."

The doors slide shut on his smile. A real smile. He understands this subtext, too.

She sits down against her desk with a deep breath. The ache between her legs is unbearable, the phantom pressure of his fingers only making it worse. Her skin is burning, her nipples puckered tight against her blouse.

She sighs, rubbing her forehead.

That backfired.