They've been working together for a year now. And she's not sleeping with him.

She's not. They're not having sex.

They're just...kissing.

It's stupid and nothing and they really should stop.

Except they don't.

She spent two weeks living under his roof without anything happening. Nothing but some significant glances, teasing grins, heartfelt good mornings and first cups of coffee that felt so domestic they made her catch her breath. But nothing happened.

She's in her new place now - Castle steadfastly ignored all her protestations of I don't need help, Castle, I can do it myself and volunteered himself and Alexis to help pack and carry and just generally ensure she gets comfortably moved in - and while it's a relief to have her own place again, she finds herself missing the company sometimes. Quiet evenings with Castle, drinking wine and watching bad movies. Mornings chatting over the newspaper before work.

It's possible they got entirely too comfortable living together, but she decides not to dwell on that.

It barely even happened the first time. It wasn't really a thing. It happened more by accident than anything. They were out for drinks with Ryan and Esposito, and then somehow Ryan and Esposito were gone and Castle was standing right there and he smelled good and somehow his lips were on hers and she couldn't breathe.

It was so quick, though.

They never talked about it.

On Monday, he walked in and she felt heat flush her cheeks. But she said nothing, just gave him an empty half-smile and looked back down at her work.

He seemed to take the hint.

And then a week later, on their way back from lunch, she dragged him into an empty stairwell and put her tongue in his mouth.

A door banged open on the floor below and they both froze, breathing hard. He looked as stunned as she felt, his mouth hanging open and so thoroughly kissable she made herself look away.

And they still didn't talk about it, because what is there to talk about?

It's nothing.

It's just kissing. That's all. It's a stupid high school nothing and there's no reason to bother herself about it. It's not like they're...touching. Or doing anything.

One day she finds herself hitting a wall; her warrants are coming in slow, the crime lab's swamped, Ryan and Esposito are out, and there's nothing she can do. No one's responding to phonecalls. She wants to throw something.

She follows Castle into the break room when he goes to refill her coffee, drags him into a corner and kisses him hard.

It's rougher than it really should be. He tenses with shock for a moment, but immediately goes with it, biting her lower lip, soothing it with his tongue. It's the same thing they've been doing, this little nothing of theirs, but then suddenly his hands are under her shirt, sliding over the small of her back, and she gasps. Oh.

The shock of new contact floods her system and Kate can't stop, winding her arms tighter around his neck, tracing the corners of his mouth with her tongue, combing her fingers through his silky hair. His body is tall, strong, broad-framed, and he has her pinned to the wall, his hips pressed against hers.

The far door clatters open and they break apart like lightning. Castle runs a hand through his hair, Kate pulls her shirt back down, and Karpowski chats with them like a normal human being who doesn't know she's just interrupted nothing that was creeping dangerously close to being something.

And that's developed into this repeated tendency to slip away when it won't be noticed and put their hands under whatever layers of clothing they're wearing. She keeps getting irritated when she has to tug his shirt out of his waistband to put her hands under it, but they're not doing anything, so they can't talk about it, so she can't say something like Please untuck your shirt so I can grope you more easily.

They keep magically finding themselves hidden in quiet corners and unused rooms and that supply closet she never, ever should have shown him. Private, but dangerous. Too dangerous for anything past heavy petting. That probably isn't by accident.

They don't take it home.

Because if they did, if they ended up at her place or his, there'd be nothing except actual self-discipline to stop this not-sex from turning into sex and that's simply not a decision she's prepared to say she could make.

In her clearer, more honest moments, Kate knows it started before this. It was already real the day she shot the man who stabbed her mother. Coonan died in front of her.

Montgomery pulled her aside and told her to go to the ladies' room, clean herself up, before she made her statement. She knew he was right. It was for the best. She was a mess.

She leaned on the sink, choking on her breath, trying to control the tight hitching in her chest. The last five minutes were flashing through her mind, an unending loop of icy fear and hopelessness when she realizes her last chance was gone, bled out on the floor.

Everything broke apart and her chest was made of stone and she scrubbed slick blood off her hands and her eyes were burning and she just couldn't stop crying.

She was vaguely aware of the door opening, the soft click of the lock, footsteps. She didn't look up. She knew who it was.

He didn't say anything. Just wrapped his arms around her, slow and gentle, and drew her into the warmth of his body. And she let him wipe her tears with his thumb, pull her close, and hold her.

It was different. It was slow. Gentle. Careful. She felt safe, surrounded in his warmth, as if somehow he were a shield between her and every shade of ugliness and death crowding around her.

His embrace was tight. And she knew what he wasn't saying. She saved his life. She could never regret that. She'd seen the fear on his face, the understanding that he might die. That the same murderer who took her mother's life might take him from her.

She pressed a soft kiss to the edge of his jaw. Castle. He was shaking. Trembling, tight and controlled under her hands, and she knew she was too and holy shit he almost died.

They stayed there for a long time, holding each other, breathing together, broken and bloody and shaking and alive.

Kate felt loved.

It's not until much later, months after she quietly admitted I've gotten used to you pulling my pigtails, that she realizes it can't possibly be called nothing anymore.

And what surprises her the most is that it doesn't scare her now.

A few days later, Kate knocks on his door and asks if he wants to go to dinner with her.

Kate takes him to her favorite Italian place, a little ristorante her mother used to love, and they laugh their way through dinner and red wine.

He walks her home and teases her when she has to dig through every pocket in her coat for her key. She shoots him a half-hearted glare.

He grins. "For the record, this was a really nice date."

Kate bites her lip. "Yeah. It was."

She leans in and kisses him soundly, long and slow and deliberate, a kiss that means everything.

It feels like a first kiss.

When she steps back, her face flushed, Castle's staring at her, dazed, his mouth soft and perfect and utterly kissable.

"Good night, Rick."

He steals one more kiss, nipping softly at her bottom lip.

"Till tomorrow."

He disappears down the hallway, and for the first time since they started this strange denial of a courtship, Kate decides it's time to simply accept it.