This isn't fair. In fact, this is distinctly unfair.

Slammed together like this, enclosed in the pitch black, trapped in a small space that is altogether too small for two grown people and this is so very unjust. They need to get out of here, and not just because their imprisonment is putting a serious dint in their ability to solve this case.

There was meant to be a natural order to things. Walls, baggage to work through. Subtext to decipher. Therapy sessions to attend. There was a gentle trajectory upon which they were meant to travel, transitioning from Castle and Beckett to… Castle and Beckett. From you and me to us.

Having their hands forced like this is unfair. It's lousy timing, and ultimately, it's not okay.

The clench in her gut is most definitely not jealousy, except it so is - how can it not be? - and the worst part… she welcomes it. If, all of a sudden, Castle's ex is on the scene, Ms. Hot-CIA-Agent herself, at least she has something to focus on beside how good Castle smells or how warm he is, pressed against her, here and now.

Kate Beckett welcomes the stab of possessiveness that pierces through her, aftershocks rolling through her veins because it's a welcome relief.

It's a refreshing relief compared to the thrum, absolute thrum, of arousal that normally courses through her, lighting every nerve ending on fire. Each and every day, she wants to cry because when she goes home - alone - she's so tightly wound that she can't stomach the thought of more of the same the next day.

And then she goes to bed - alone - and works out all the tension, until, just as expected, it starts again the next day as Castle hands her a cup of coffee.

Except now, the jealousy is tamped back down, a myriad feelings fleeting through her mind as she tries to get a handle on the situation in which they've now found themselves and - Oh. Crap. Handle. Hands. No!

She jerks her hand away because no, she's not going to touch him. Not now. Not ever.

Never mind that they're lying face to face, on their sides, shoved into the trunk of a car in what might be the most inconveniently timed opportunity for her hormones to show their face.

Maybe not not ever, Beckett.

The reminder she thrusts at herself is-

Fuck.

Hands? No. Thrusts? Absolutely not.

They're just in a tight space and if-

It could happen to anyone.

It could so happen to anyone.

The fact this case is classified is, at this point, a fucking relief, because she does not want to have to write this up, doesn't want to watch Ryan and Esposito snicker as they read the report and make bad jokes about just how closely she and Castle were pressed together.

Too close, is about all she has to say about that, because he's so - oh.

Oh, god. Is that? No.

She attempts to wriggle back, because if he is enjoying this, she absolutely does not want to know. No. No, she doesn't. And if she shifts forward again-

Beckett!

Stop!

It's awkward, and it's Castle, and you're friends. You can handle this.

Except the pep talk does nothing because handle, and hands, again and now her right hand is on his left bicep and holy-

Yeah.

That's not jealousy, any more.

His former muse is nowhere to be seen, and the arousal is back and if she just edges her way forward-

Shit.

This is not okay. It's so far beyond not okay, and it's not fair. It's just been a really long time. And if his leg is pressed between hers, it is completely and utterly not her fault if a flood of desire is rushing through her.

"Beckett?" he asks, his whisper loud in the deafening silence of the trunk of the car.

She bites down on her lip instead of answering him, because what on earth can she say right now? 'It's okay, Castle, I'll ignore the fact your erection is painfully obvious?'

She stays silent.

"I- uh- sorry," he manages to get out and she shakes her head because there is no denying what is going on here. With him. Not with her. Well, with her too, but she's at least in a position to deny it, whereas pressed hard between-

Hard.

Fuck.

She's so screwed and she rolls her eyes because Castle is the king of puns, not her, but-

He shifts against her, and the pressure on her thigh is almost removed. Except that it's not removed, just… relocated, he's just moved and she can feel his… hardness all the more readily. Pressing against the seam of her pants and all she wants to do is rock her hips against him, and-

If - when - they get out of here, she's going to have to change her underwear.

Maybe her pants.

Oh god.

Pants.

She wants his off. She wants-

She moves. Oh, this is embarrassing. She didn't mean to migrate even closer to him, but her hips shifted and she rocked against him and-

Oh damn.

She's doing it again, except this time-

He's moving too.

"Beckett," he murmurs, bringing his hand to her face, cupping her jaw, and if that touch isn't the most exquisite, gentle, arousing-

She didn't even know that having a thumb run its way down her jaw onto her throat could be that arousing and she shakes her head just the tiniest bit, a minute movement sending his hesitant hand flying; he jerks away from her, but then his fingers come to rest on her breast and if a touch to the face was something, this - over her t-shirt, over her bra - is everything.

"Sorry," he gasps, and she shakes her head, grabbing his wrist before he can remove it from her. "I'm- Beckett?"

"No," she gets out, a strangled sound that's barely word-like as she grasps his hand, pressing it, firstly, more firmly against her breast before nudging him down, pushing her shirt up until he gets the idea, and slides his hand into the opening, across her skin, over her bra, then - thank god, at last! - under her bra, his thumb making contact with her nipple.

"Beckett?" he asks again, and she nods, well aware that he can barely see her, he's not much more than a silhouette in this lack of light. Her eyes have adjusted as best they can, just enough to distinguish between him and what little space surrounds them.

"Castle," she responds, using the sound of his voice, rather than relying on her eyes, to track his face. She shifts again, her hips no longer moving of their own volition. She wants this, she's choosing this, and damn, it should not be possible that she's this aroused just because his hand is on her breast, his thumb rubbing circles harder and harder, and she grinds against him.

How is it that he feels so good - so right - while they're both fully clothed?

She's torn; her own free hand, the one not trapped beneath her as she lays mostly on her side, is still on his arm. She can't stand the thought of moving so that he's not trapped against her, providing hard pressure against the seam of her pants, against her jeans, but as long as he's touching her nipple - she moans, because fuck, that alone could get her off - she needs to touch him.

She needs to touch him and she rocks back to gain just enough room to slide her fingers between them, cupping him first through his pants, and then wrestling with the button on his pants, the zipper, until she frees him, his cock hard and throbbing in her hand.

Fuck this small space.

She wants to taste him.

She wants him inside her.

Neither of those things are going to happen, and she satisfies herself by silently promising herself that next time will be different.

Very different.

In the meantime, she'll work with what she's got, and she wraps her hand around his shaft, moaning at the feel of him, running her thumb over his tip and crying out as he shudders.

It's his turn to move and the hand that was in her bra moves - she keens at the loss - but he brings it down, his fingers nimble as they undo her pants before he slides his warm hand into her panties.

She exhales - is it a groan? A moan? - as, finally, he runs his fingers through her folds. She's wet, she knows that, but he swears under his breath and as he gasps out her name, "fuck, Kate," she thinks she finally understands just what she does to him.

If the throbbing cock in her hand wasn't enough evidence.

"At least this time we're not handcuffed together." The inane thought bubbles up, unbidden, and is out of her mouth before she can stop it. 'You'd better not be enjoying this', she'd told him then, aware, of course, of the fact he was enjoying it rather a lot.

She'd praised herself for concealing her own arousal at the time.

Her own self-control hasn't lasted long, she muses, grunting as Castle finally - finally - slides into her; first one finger, then a second, his thumb steady against her clit. She rocks against him as he thrusts with his hand, his fingers finding her g-spot.

She's not going to last much longer.

They've been in the confined space for - she can't even hazard a guess, not long - but this has been building.

Since they were cuffed together.

Since they kissed to distract that guard.

Since she first told him he had no idea.

She closes her eyes, loses herself to sensation, because damn. What this man can do with his hand is nothing short of magical. If he can bring her this close, stilling just at the right moment to leave her on the edge, letting the wave ride out before moving again, what will it be like when his mouth is on her? When he's inside her?

It's this thought that pushes her over the edge and she cries out as she comes, her muscles clenching around him over and over again.

Somewhere in her mindnumbingly beautiful oblivion she becomes aware that her own hand is still rhythmically stroking his cock. She sighs aloud in satisfaction as she feels him come too, her hands, the bottom of her shirt, wet now.

"Beckett?" he whispers, not for the first time since they've been trapped in the car together, but this is the first time she responds to the hesitancy in his voice, the fear, the apprehension.

"Shut up, Castle," she rasps out, "and kiss me."

A/N: Kink meme prompt. Summer 2015. In close quarters; they can't hide their mutual arousal any longer and finally get each other off. Any time pre Always.

I am blushing. You can thank Kylie and Jamie for forcing me to hit publish. Still, bucket list goal achieved, M fic written. No idea if this is the first in a career of many M fics, or the last, haha!