This is set sometime during season 1, after Kate finds out her fictional self is Nikki Heat.

When Castle brings in breakfast for everybody, at first she thinks nothing is wrong.

The entire population of the fourth floor descends on him as he comes in carrying boxes full of doughnuts. Kate chuckles, shakes her head, looks back down at her work. He was devastated the day she told him cops don't always eat doughnuts. Apparently he's trying to live his fantasy anyway. That's...well, kind of sad. But he's certainly making friends.

"Morning."

Kate looks up, startled, at the coffee that seems to simply materialize on her desk. "Good m-" She eyes him suspiciously for a long moment. Something's definitely wrong. He's not talking. He's not staring at her creepily. Castle is sitting quietly in his chair, hands folded in his lap.

This is - disconcerting.

"Something wrong?"

"Hmm? Uh, no." He forces a smile, but it's wrong, it's all wrong. He's avoiding her eyes. She's only just gotten used to his staring, his creepy, stalkerish focus on her and her alone (she does not like it, she doesn't). But this is genuinely weirding her out.

"Castle."

"What?"

"What's going on?"

He makes a slightly more effective attempt to meet her eyes, only to quickly look away. "Nothing, Detective. Everything's fine."

She'd be offended at how badly he's lying, but honestly, she's more on edge than offended. She types blindly, running through a standard weekly report, giving herself time to think without him pestering her.

He left early last night. Claimed he had to write. Seemed fine then. She hasn't heard anything indicating something out of the ordinary happened. And he's here on time, so it's doubtful anything happened this morning to throw him off.

"You were, uh, writing last night?"

A momentary hint of panic flares up in his eyes, but he just nods. Well. That's clear enough. The question really seems to be what did he write last night?

Well, what does she know about his writing? He's writing a detective, based on her, named Nikki Heat - Kate silently grits her teeth but lets it go for now - and as far as she knows, there's nothing to worry her. She's gonna be really smart. Savvy. Good at her job. Haunting good looks. And kind of slutty.

Oh no.

Kate clearly remembers that scene where Clara Strike got Storm into her bedroom and got her hands on his -

- and Castle won't meet her eyes.

He's staring at her mouth.

Her eyes go wide. Oh no. No, no no no, it can't be - oh no, that is creepy -

"Castle. Look at me." He meets her eyes, and shit, shit, that's what she was afraid of. He looks guilty. He looks like he's afraid she knows something, and dammit straight to hell she's afraid she knows something too. "Something's going on, and I want you to tell me what it is." She...probably doesn't want to know, but at this point her imagination is probably worse than the truth. It has to be. Right?

"It's - it's nothing," he shrugs. "It's stupid."

"Castle. Did you - " oh, she's not sure exactly how to say this but there is no version of it that isn't awkward - "are you writing - romantic scenes for this book?"

From the shocked expression, the way his ears are getting red...yeah. Yeah, she knows. Kate clenches her teeth. So Castle's writing sex scenes with Nikki Heat. That's not so bad. It's not like she wasn't -

- although when Ryan and Esposito find out about this, she is never going to hear the end of it.

"I'm sorry?"

She shakes her head, presses her lips together. "It's fine. Just - it's fine." This is not going to get to her. It's not. "It's just a book. It's fiction, right?"

Silence.

She flicks a glance up at him and stops short. He's - he - he looks - mortified. He looks scared.

What - ?

It's just a book.

Wait.

If -

Her cheeks get hot. No. Seriously. No -

- oh God no no no.

He's watching her face, and she knows he can see the moment she figures out exactly what he did last night while writing a sex scene about her.

He swallows. "I mean - not - "

"Castle. Stop talking."

He shuts his mouth. But it's too late. Now her mind is swimming with images that -

She is not ever going to think about it. No. What he does in his bedroom is his business.

Or maybe it was a different room.

Maybe he got into his shower and slid his hands -

Shut up shut up shut up.

"Hey guys. You want some chow? We got two more doughnuts here."

Kate silently blesses Esposito for breaking up her terribly vivid train of thought. "Sure, thanks."

She reaches into the box, only to find the two remaining doughnuts are bavarian cream-filled long johns.

No.

Just no.

She pulls her hand back. "Uh, actually, no thanks, Esposito."

Castle, of course, takes one. She grabs her coffee and walks away before she has to see him bite into the doughnut and get bavarian cream all over his hands.

This is not her day. She wonders if she can convince the captain to let her pour some stronger "flavoring" into her morning caffeine. Because no way in hell is she letting Castle put cream in her coffee today.

a/n: I kind of...wanted to see how dirty I could write something without actually writing anything dirty.