Title: Critical Mass

Author: Eyrianone

Rating: T

Spoilers: Post Countdown, happens lets say a week later.

Summary:"I'm . . . I'm in love with you." He replies. It's out there now, acknowledged, this force that binds them, but even the writer in him doesn't know what will happen next.

Disclaimer: Nothing of what you recognize is mine, I just can't get Richard Castle out of my head – and I have a cousin whose name is actually Richard Castle – awesome huh?

Authors Notes: To any reader of my 'Bones' fiction 'Upside Down' you will get an update this week – promise – this delayed it, but Rick Castle is wonderful, guess I'll take on more than I planned.

In his heart he's not really surprised when it all boils over, pushing her hard up against the wall he kisses her in a fashion he's only ever written about, in a manner that can only be described as 'devouring'. There doesn't seem to be any way to get her close enough, with her trademark four inch heels she's almost nose to nose with him, but her body is half the size of his strong masculine form, she's slender, lithe but strong beneath his questing hands.

It's been coming since the night of their 'undercover distraction' kiss. Like they cracked the seal on nuclear reactor that night, and now the chain-reaction is finally spiraling out of control. Their chemistry, that instant pull that has been there since the day they met, slowly growing from a simple physical attraction into a magnetic force as their friendship began, grew, became close and finally blossomed into love – at least on his part; and he hopes on hers too. Beckett has always maintained she's the 'one and done' kind, and he wants to be her 'one' more than anything in this life.

She moans suddenly into his mouth and the last rational part of his brain that was aware of where they are flees, she consumes him, every functioning part of him focuses like a laser on her and he hitches her up the wall, her legs immediately going around his waist he lets the full force of his desire for her rule, pushing himself against her so she understands exactly what she's doing to him. His reward is another mewl-like sound from the back of her throat and she breaks from their kiss for one brief heart-stopping moment. Gasping his name once, "Rick", she dives right back into the inferno in search of more.

It's been a rough week for him, leaving her alone at the precinct with Josh, swallowing the invitation he'd been about to utter as he noticed the handsome cardiac surgeon approaching, he'd leaned back against the wall as the elevator doors closed, and sighed brokenly. He didn't want to be alone that night, but with his family safely out of town until the following morning, and Josh . . . Josh still in the picture; he had not been willing to disturb Kate's peace. She was in a relationship, one she wanted to make work, and he knew that his baggage made seeing him in the light he wanted her too – hard at best.

Two failed marriages and years as a famously philandering playboy – an image, a somewhat carefully crafted one, but a picture he knew she believed. Was she ready to learn that it wasn't really who he was, would she ever suddenly see, all by herself that he'd begun to leave that person behind him within months of starting to shadow her.

He's always known that for them to become what he wants them to become she has to realize that loving her has altered him and for her – only for her he can be so much more.

For her he will willingly risk his life, walk into situations he has no training for, watch her back, take a bullet if necessary, get blown up, die of radiation poisoning or freeze to death. For her there is no limit to what he is willing to become, even if this means being patient, being a friend and waiting this relationship of hers out . . . because he knows they belong together, he knows, but she has to know too.

Her hand tangles itself, buries itself in his thick shiny hair, she tugs at his scalp, pulling him in deeper, deeper, molding herself to him. The next moan is his; pulled up from deep inside his chest it rips from him in the milliseconds when their mouths aren't fused. Someone is going to catch them any moment if they don't keep it down, his brain can process this thought, but the pull of her, the heat singing down his veins, and hardening his body is force far to strong to deny.

This is his reality, the universe that he inhabits. That he simply cannot stay away from her, cannot deny her anything she could ask of him, he will give her the world and every part of his soul before his life is through.

Her name is carved on his heart, distractions like his reunion with Gina aside, he's really been hers for so long now that his life before she came along seems a world away entirely, a reality where only Alexis is real, and the man he used to be is a stranger to him in all ways bar the father he remains.

"It's not about the books anymore." He told his mother, the truth is it never really was. It was about Beckett, about the desire she stirred up in him, about the pain he needed to vanquish that clouded her emerald eyes, about the fantasies of her, of them, that became two further best-sellers to add to his impressive resume. It was about the man he suddenly could see in the mirror, the one who would prove he was worthy of woman like her, who would stick like glue – 'always' until she could see that man too.

Her tongue licks along his upper lip and a full-body shudder goes right though him, he desperately wants her naked and beneath him, he's aching and dangerously close to the edge – fully clothed and in an interrogation room.

They should stop, they should talk, this is as wrong as it's oh my God amazingly right and he's trying to clear his head enough to real himself in when she breaks their kiss, tightens her legs around him and he sees by the sheer ecstasy on her beautiful face that she's crashed over that edge, her head thudding against the wall.

Neither hears the door to the room open, but suddenly her name is spoken in a harsh angry tone and Castle knows without looking that this has gone from wrong to really wrong as Kate's eyes focus suddenly and she goes rigid and pales.

"Josh . . ." Her voice is a barely formed whisper, her face distorts in distress, which he feels keenly, 'this' isn't her . . . she's the most honest person he's ever met.

Terrified his blue gaze finds hers; she opens her mouth to speak and for a moment he swears his heart stops beating, dread like a lead weight settles across his chest.

"Castle . . ." She says, and the use of this name, not "Rick" is like an ice-pick into his heart.

"Kate . . . please." He pleads, begging her with ever fiber of his existence to not flee.

"Rick." She relents. "I have to explain . . . I have to go . . . you have to let me." She says.

He nods. Shifting he sets her upon her feet and taking an unsteady breath he forces himself to let go of her, it might be the hardest thing he's ever done, to release her now.

She steps around him on trembling legs, the aftershocks of passion thrumming through her. Hand on the door she turns, head bowed, breathing uneven she finds herself unable to leave him like this.

"Rick." Softly her voice caresses his name, and he turns, guilt and fear and longing and desire written all over the face she's come to love most in the entire world.

"This wasn't your fault . . . what's between us; this is what happens when people live in denial too long. I'm the one involved with someone else; the fault here is mine okay."

"I'm . . . I'm in love with you." He replies.

She musters a smile. "I . . . ditto." She tells him before she tugs the door open and leaves.

Castle sinks down into a chair at the table, shaking hands running through his hair, he wills his body to calm and his heart to stop its frantic racing. It's out there now, acknowledged, this force that binds them, but even the writer in him doesn't know what will happen next.