a/n: Slight AU insert for Set Up, in which Beckett can no longer keep her hands to herself.

Since that first time, for the cover, she finds that they've been putting themselves in precarious positions where the brush of fingers, the lingering of gazes, the brush of lips, is almost inevitable. Dark corners of the precinct, a thumping club with one eye on her target and one eye lingering on a mouth too full of life to ever resist.

Castle's pitch black loft with a do it yourself murder board and no one else in sight.

There's a bomb somewhere in her city ticking away the seconds of her life one moment at a time and it's putting her on edge, making her feel desperate, aware. Once she would have welcomed the finality, welcomed the increased pressure to perform, the throb of her brain behind her eyes, the risk so high that the stakes are all or nothing. For her, it is always all or nothing, but in these situations, it gives her an excuse.

Now, though. Something suspiciously like panic claws at her insides, ripping gauges against the lining of her stomach for all the things she hasn't yet had the time to do.

The air in the room changes as Castle stops talking, noting her distraction on the couch next to him. They lock eyes as she tries to push down the familiar impulse to lean forward. Castle pouts unexpectedly, throwing her off guard for a moment as she breathes a what? into the space between them.

"You totally missed my brilliant plan for finding the bomb," he says.

She tilts her head, regarding him for a moment as a smile almost quirks at the corners of her lips. Even in a situation like this, Castle's ego is present and accounted for, and she finds it strangely comforting.

"Castle, what if we don't find it?" she asks, getting serious, voice steady despite the adrenaline she feels pumping through her veins.

It's so unlike her to ever truly consider defeat that Castle's eyes seem to take an extra second to process what she's said. His answer is not yet voiced, but she can see it there, forming in the lines of his face, the way his entire expression softens and then steels itself up all at the same time. Whatever he's about to say is something he believes so absolutely that there is not even a hint of doubt creeping in behind that blue stare.

"Beckett," he starts, addressing her as a cop in the voice he usually saves for Kate. One of his fingers comes up to slide the hair on her forehead out of her eyes and hook it behind an ear, leaving her gaze completely open to him. It would make her want to put some distance between them if she didn't hear an incessant tick tick tick in the back of her skull.

She doesn't let him finish.

Words of encouragement, explanations of why he chose her for his muse, always, everything, get lost and disperse into the heavily charged air around them when she impulsively closes the distance between their faces to capture his lips with her own.

She wonders if this is what bombers feel, the compulsion to press that detonator just for the thrill of release.

A soft moan tumbles from Beckett's mouth as she feels him respond to her, shift closer, press. The hand at the side of her head slips down, cupping the back of her neck, and she tilts her head back into the warmth there. The change in angle leaves her lips parted and he chases her, sliding their tongues together as her fist closes around the lapel of the jacket he is still wearing. It feels like a natural progression for her to use her grip on him to move closer, to slide into his lap, and neither are particularly surprised to find her perched atop him with both knees hugging his hips, and a soft hoodie pressed to his chest in only a matter of seconds.

Once that fuse catches, the flame cannot be called back.

Beckett squirms, struggling to get closer to him, to increase their contact even though there is barely any space between them. They are both wearing too many clothes. As she feels Castle's mouth release her, start mapping a hot trail down the column of her throat, she can hear the teeth on the zipper of her sweatshirt start to separate as his hand drags it down achingly slowly. She would rush him, push him like he always pushes her, but the hot slide of the flat of his tongue across her pulse point leaves her dizzy and incapable of doing anything but holding on for the ride.

Her knees spread wider, hips rolling forward almost of their own accord as she feels the two sides of her sweatshirt start to separate. She's about to shrug off her outer jacket when a shrill ring jolts her movements, causing her to flinch, and Castle to bite down on the place he had been so lovingly tending to.

She pulls him away from her skin by the hair on the back of his head, his mouth coming away with a soft pop of saliva. "Sorry," he mumbles as he leans forward to kiss the teeth marks he has surely left behind.

The ring sounds again, but before Beckett can untangle her hands enough to pull the phone from her back pocket, Castle's quicker fingers slide behind her to extricate it himself. She can still feel the vibration of it along her backside as he slides it out, using his convenient hand placement to press her front as close to him as it had been before.

She tuts as he holds her phone out of reach, looking like he wants to throw it across the room. She almost lets him.

"Who is it?" she asks, voice coming out much breathier than anticipated. It rings again as he looks at the display, still holding it higher than she can reach. "Castle."

"Ryan," he says, sighing.

The tick tick tick sounds in the corners of her mind again, reminding her of why they're here at all.

He presses answer and slides the phone through her hair and against her ear for her before letting it go. The brush of their fingers at the hand off distracts her, but she forces her mind to the case as she pulls in a calming breath and speaks her name into the receiver in her usual all-business tone of voice. Ryan's got a good lead on the bomb, is calling her from his squad car since they've officially been kicked off the case, but that matters even less here than it would in any other situation. This is her city, and she's not about to be kept out of the loop. Her eyes linger over Castle's face as she listens to the younger detective spout off what they've learned since she and Castle left the precinct. It all sinks into her brain, but her focus wanes a little bit as she watches the flicker of the white light from their murder board reflect across his face. There are deep shadows there that are not normally present, and it makes this moment feel serious.

He gives her a knowing smirk when her eyes make their way back to his, caught staring absolutely. For all the times this situation is reversed, she thinks he can give her this one. It's only a few moments before his hands start getting impatient; she feels like he's touching her everywhere as his fingers trace along her thighs, her stomach, the backs of her knees. One hand is traveling a path dangerously close to the inseam of her jeans and she finds herself holding her breath against the onslaught of sensations tingling through her lower belly. His eyes drink in her reaction, watching her pupils dilate in the dim light, the way she worries her bottom lip to keep from making a sound into the phone, the slight arch of her back as his thumb brushes lightly down her zipper. He's scrutinizing her the way he does when he's collecting data for Nikki Heat, but she would bet money that none of this will ever show up in one of his books. This is theirs, and he's not the sharing type.

She hangs up abruptly when Ryan has to go, fisting her phone and lurching forward to pull a quick and dirty kiss from Castle's lips. Her tongue traces the roof of his mouth as his slides along the underside of hers, sending a white hot jolt of arousal to the place where Castle's thumb is still resting much too casually. She pulls back quickly with a last nip of her teeth, his lips shiny from her attentions, following her face as if she were a magnet. She halts him with a finger across his lips, stilling him and shushing him in one motion. "We have a lead," she says apologetically, and then her voice lowers an octave. "To be continued?"

(If he is surprised by her willingness to pick this up at a later date, to actually acknowledge that this moment has occurred, his face doesn't show it.)

He's reaching for her already as she swings herself off of him and onto her feet, re-zipping her sweatshirt and running a hand through her mussed hair. When she glances back toward him on the couch, he looks like he wants to protest. Loudly.

"Oh come on Castle," she says, brushing past him to turn off his projector, plunging them into darkness so she can't see the hungry look in his eyes. "Going on rogue missions is your favorite part of this job."

She can't see him clearly, but as she makes her way toward his front door she hears him stand up and mumble under his breath, "maybe one of my favorite parts." She smiles at this, still feeling the pleasant buzz on her lips from his kisses, and drags a finger across her mouth.

He's behind her then, unexpectedly pressing his front into her back as he traps her against the front door. She gasps softly at the intrusion, closes her eyes despite the complete lack of light. His breath is warm against her ear, puffing in a way that reveals exactly how worked up he still is from their time on the couch. It makes her shiver.

"We're not done here," he says softly, confidently, not giving her an out. She doesn't even want one anymore.

"After."

"After," he agrees. "Let's go stop that bomb." He steps around her and is out of the door before she can follow, the bright light of the hallway spilling in over her shoes. She stands there, soaking in the moment for just another second before heading back out into the real world.

Tick tick tick, she hears as she closes Castle's door behind her.

Even with the threat of the bomb looming over her, she feels alive.