She doesn't plan on showing up outside Castle's door.

XXX

He follows her down to her car like a puppy. Beckett stops, just before opening her door, and looks at him over the roof of the car. Castle doesn't notice. Instead, he pulls at the door and frowns when it doesn't open. "Beckett, I think-" He stops when their eyes meet. "Beckett?"

She feels sick, and every time he looks at her like he'll follow her to the ends of the earth she actually feels worse (because she's dragging him through this, because she feels like grabbing his hand and saying Here, let's fall down this rabbit hole and take the whole goddamn world with us).

"Beckett?"

She unlocks the car and slides into the driver's seat.

XXX

"Lady, what part of 'no cops' didn't you understand?"

"He's not a cop." Beckett wants to shout it at Raglan, and maybe even Castle too. He's not a cop, is not even remotely close to qualifying as a cop, and he doesn't belong here. But part of her is screaming Oh but he does, he does, he does.

"Who the hell is he then?"

"Someone I trust."

(Castle's been threatened and shot at since day one and hasn't left her side yet. If anyone deserves her trust it's him.)

XXX

"I'm up for dumb ideas, Castle."

"I've got one." Let's act like a drunk couple. He doesn't really expect her to agree to it. Actually, he expects her to frown and then punch him, maybe even shoot some essential part of his anatomy.

"What is it, Castle?"

"Well, we need to...maybe..."

"Castle."

"Act drunk."

"What?"

"He'll never expect a drunk couple out for a walk to be packing heat, right?"

Beckett doesn't frown, doesn't laugh, doesn't even whip out her gun to start threatening him.

This is serious.

"OK," she says with a little nod as if to reassure herself. "OK."

Castle grips the door handle of the car. This is serious. The metal is cool under his warm skin. "Beckett, are you sure-"

She pushes herself away from the car before he even has time to finish.

Deep breath. He's drunk. He's just spent the night at a bar with a beautiful woman. Another deep breath. Showtime.

Beckett's already giggling like a college sophomore, and it's such an uncharacteristic sound that Castle can't help but chuckle along with her. Then she grips his coat hard, and almost sends him face first into the ground. This is really convincing drunk acting. Castle makes a note to ask Beckett about it later.

Maybe when there aren't lives at stake.

"Kate." Castle's not really sure if he says it out loud. He wraps an arm around her, pulling her closer. He even has time to cast a grim smile in the direction of the ground; he's holding Kate Beckett. She's warm and smells like vanilla, and it makes absolutely no difference to him that this isn't how he imagined a moment like this might play out.

He's not sure what makes him stop her from grabbing her gun, but he tells himself that everything will be fine if he just stops her from shooting someone. So he grabs her hand hard and tries to ignore the startled look that she gives him.

Everything will be fine.

He kisses her then. Mainly because he thinks it's necessary to try and maintain their cover (but also just because he can). Her pulse pounds beneath his fingertips, and maybemaybemaybe skitters through his head, and then there is only him and her, wrapped around each other in a darkened street.

XXX

Later, when they're sitting in the back of an ambulance, bruised and battered and still shaking from the rush of adrenaline, but whole and alive, they'll both think about the kiss.

(Actually, they'll both think about it more than just the once.)

XXX

There are days when Castle desperately wants to ask Beckett to run away with him.

Today is one of those days.

Beckett won't move from her desk. She's been pouring over financials and backgrounds for the past three hours, and Castle is so bored.

There's really only one solution.

He reaches over and snatches the case file from her hands.

"Castle," she snaps, "give it back."

"No," he says, rising from his chair and taking several steps back toward Ryan and Esposito's desks.

Beckett frowns. "Castle."

"No." He takes a few more steps until he's behind Esposito. Beckett chucks a pencil in Castle's direction, but he ducks, and the pencil bounces off Esposito's head instead.

"Hey!"

"Sorry Esposito," she grumbles, moving toward Castle, who in turn is making his way toward the elevator.

"Run, run as fast as you can," Ryan says with a smile and a nod of encouragement to Castle, who smiles conspiratorially, and bolts over to the open elevator.

"You can't catch me, I'm the Gingerbread Man!" Castle sing-songs as he jabs at the 'door close' button. He looks up with a sigh of relief as the doors slide shut, only to discover that Beckett is standing next to him, her arms crossed.

"Castle," she says in a dangerous voice.

"Beckett," he replies, trying to match her frustration. She rolls her eyes and grabs at the folder in Castle's hand. He moves it quickly out of her reach, holding it up over her head.

"Castle."

He holds up a finger, silencing her. "I'll give it back to you," he says, slipping the folder into his coat, "if you will go get something to eat."

"With you."

"Yes."

Beckett studies his face and sees something new resting in his eyes; he's looking at her differently.

"Beckett?"

All she can hear is that was amazing.

XXX

"I bet he's a doctor."

"What?"

"This psycho killer. I bet he's a doctor." And he probably has a motorcycle and dates detectives.

"Castle." Her tone has taken on a warning tone, but it's much too late, because he's already lost control of his tongue.

"And he lies to everyone and always, in the back of his head, is the primal urge to kill, kill, kill. He can't block it out, even when he's in the middle of an emergency medical operation. He stops and thinks to himself I could just slit this vein, cut this organ, no one will ever know. And he's so charming that he gets away with everything."

"Castle." Her voice is much sharper now, but Castle can't help it. Out of spite, he continues, weaving a story in which the murderous doctor goes on a rampage through his hospital and holds most of the occupants hostage (nurses, doctors, and patients - the whole damn hospital Castle decides). Then, one by one, the doctor kills them all, later escaping prosecution by manipulating a young female detective.

When Castle finishes, he finds that Beckett won't talk to him.

XXX

Later, when his jealousy has calmed and her anger has cooled, Castle apologizes.

Beckett gives him a tight smile that he can barely see in the dim half-light of the closing precinct. Castle wants to tell her that he didn't mean any of what he said (after all, implying that Josh is a murderer isn't really going to get him anywhere).

He finds that he can't.