A/N: This story didn't end up going in the same direction I expected it to when I started writing. I decided to let it take me along for the ride, and here's what happened.

Disclaimer: I don't own Castle or any of the characters. Andrew Marlowe & Co. are doing a fantastic job...I'm just having some fun.

She was going to leave.

She was actually halfway across the room when several thoughts collided and brought her to an abrupt stop. Fortunate to avoid a messy crash with a well-dressed server and his balanced tray of champagne glasses, she paused long enough to consider her options. Sure, she was still reeling from her little spat with Castle in front of the Heat Wave display, but storming out now would send her past a still-hungry crowd of photographers and tabloid reporters; she had no desire to run that gauntlet again. Enjoying a nice night out with Montgomery, Ryan, and Esposito would probably be good for her. There was an open bar, plus the hundreds of bubbles dancing within arm's reach. And she had spent way too long – longer than she'd ever admit – getting ready for this party, so flaunting her mile-long legs in front of an arrogant writer was appealing. She knew she looked damn good, so why not fight ego with ego?

Kate Beckett swiped a glass from the befuddled server and gracefully turned to find her coworkers. Her long necklace skipped against her abdomen, and her swaying hips drew attention from more than one admirer. She slid into place next to Esposito and took a long swallow of champagne. The liquid tickled on the way down, but settled pleasantly in her chest, dismissing any lasting tension. She was ready to enjoy herself.

Though they avoided talking about the 12th, they managed to cover plenty of non-work topics and she was grateful that she had reconsidered her premature escape. Beckett's laughter and conversation with her coworkers were admittedly punctuated by furtive glances around the room, and she was on the receiving end of more than one raised eyebrow from Montgomery, but she thought she was doing an admirable job of relaxing and pushing Castle from her mind. And being two-thirds of the way through her second glass of champagne probably didn't hurt. If Castle was that eager to drop Nikki Heat for a famous British spy, so be it. She didn't need him in her life; wouldn't miss him at all. Absolutely not. Beckett tipped her head back, emptied the glass, and set it down on a nearby table.

"So, how are all my favorite detectives, and their fearless leader, doing tonight? Having fun on your night off from murder and mayhem?"

Spinning around, slightly too quickly for her happily heavy head, she saw Castle clasp his hand on Ryan's shoulder. The cocky grin on his unshaven face made her eyes roll and her heart jump, so she reached into her clutch for her phone. The boys were already excitedly thanking Castle for including them in his big night, and she wasn't terribly worried about being able to slip away.

"Excuse me, I'm just going to go check my voice mail and use the restroom. I'll be back in a bit."

Montgomery nodded his acknowledgment and she caught a flash of unnecessary concern on Castle's face as she turned to leave. Scanning the room for an indication of where she needed to go, Beckett worked her way through the crowd until she found the relatively quiet corridor, restrooms tucked inconspicuously toward the end.

Pulling up her messages, she leaned against the wall with one shoulder and closed her eyes, shutting out the night's undulant emotions. While curling her hair earlier in the evening, she had stared into the mirror and attempted to calm the butterflies in her stomach. Yes, she was attending a VIP book launch party for her favorite author, and the fangirl inside her screamed with excitement. But, she reminded herself, she had found a conceited man behind the curtain, one who couldn't be counted on to stay focused on anything, or anyone, for long.

Beckett sighed and brought herself back to the present, realizing that his willingness to walk away from the precinct proved his lack of interest. Utterly distracted and unsettled, she looked back down at her phone and didn't hear him approach. When his broad hand spanned her waist, she jumped, barely managing to keep from inflicting serious damage in a moment of self-defense.

"Castle, why the fuck are you sneaking up on me?"

He leaned forward, his chest pressed against her back, and spoke softly into her ear. "Relax, Beckett. I just wanted to apologize. I didn't mean what I said about Nikki Heat."

His scent crawled across the sensitive skin of her neck and cascaded down her unusually exposed chest until it wrapped her in its warmth. The rhythmic breath at her temple made her eyes slam shut again, desperate to contain the shiver threatening to travel the length of her body. Seemingly unaware of her reaction to him, and possibly anxious about her long silence, Castle tightened his grip on her waist, and Beckett swore the heat was burning a handprint through her expensive blue dress.

She didn't move.

"I…Castle…I'm sorry, too." She took a deep breath, willing herself to sound like she was in control of her own body. Like it wasn't about to abandon her head and run off in a bookstore-borne fantasy. "You've been given an incredible opportunity and nobody would suggest you turn it down to write about a random cop."

He paused. "She's not a random cop. She's much more."

Well, so much for containing the shiver; it burst from somewhere deep in her core and left goose bumps in its wake. "She's more?"

Castle finally caught on, the evidence of her innate response to him tangible now. Honestly, she was fortunate to have escaped even a minute of his scrutiny, but the brief lapse in surveillance had come and gone. Never one to let a fortuitous moment pass, he slid his hand across her stomach, strumming one of the seams of her dress with his thumb and pulling her tighter against him.

"Yes. She's a fierce defender of justice. A brilliant voice for the victims. A guiding light for the ones left behind. She's an enthralling tangle of contradictions: sharp and soft, courageous and frightened, loving and distant. She makes the people around her want to be better than they are, because she holds her head high and shows them the way. She's someone women want to be, but someone with whom men don't want to fall in love, because if they do, they may never get over it."

The whispered words held her in place, just as surely as they made her want to run. She couldn't tell whether Castle was talking about Nikki Heat anymore, and she knew that was the point. Keeping herself steady, unwilling to turn around and look at him, she spoke softly.

"So, what are you going to do?"

He chuckled, the sound infinitely more erotic than it should have been. "I'm going to think about the book offer. Nothing needs to be decided tonight and it's much more complicated than I should probably admit. In the meantime, I'm going to step away from you and rejoin the party."

Beckett opened her mouth to respond, maybe even protest, but Castle lifted his hand and pushed a finger against her lips to silence her. Then he lowered that same finger and began to trace the downward path of her delicate necklace. "While I'm making the rounds, thanking everyone for their support, and giving them the photo ops they want, I'll be remembering the way this was wrapped so seductively around your neck, dangling as a tease for everyone who would dare to let their gaze drop just as low."

"Castle-" Her back arched of its own volition, her ass pressed into him while his strong heartbeat pulsed against her shoulder blade.

He moved to the deep neckline of her dress, his finger following the edge and skating along the surface of her skin. "And I'll be jealous of this damn dress, a beautiful piece of material that gets to maintain such intimate contact with your body, while I gawk like an inexperienced teenager."

That got a laugh out of her, breaking enough of the tension for her to find some strength in her voice. "You're not even close to inexperienced, Castle."

"No, I'm not inexperienced. But I'm also not what you've seen on Page Six, Beckett." He sounded sad, regretful, and she was sorry that she had brought it up. Her comment had changed the tone of their conversation so abruptly. Dropping her phone back into her clutch, she used her free hand to cover his, holding it against her bare chest. She hoped it would encourage him, and it did. He continued carefully.

"When I'm done here, I'm going to take my mother and daughter home, and then I'm going to ask my driver to bring me to your place. I'm hoping you will let me in, not because I want you to be a conquest, but because I don't want this night to end so soon." He touched his lips to the back of her neck in a tender kiss, effectively lighting the fuse that he had so gently threaded through her veins.

She trembled, fear and anticipation so intertwined that she couldn't tell them apart.

"I'll let you in."

Castle found himself unable to stand still, pacing within the confines of her building's elevator. He had done exactly as he said he would; he socialized as expected, saw his family back to the loft, and then came here, telling his driver to take the rest of the night off in a moment of unabashed hope. Now, he was questioning everything. There was no denying that he had been attracted to Kate Beckett from the instant he met her. And he couldn't help but smile when he realized their introduction had come at his last book launch party, the poetic fate of it almost breathtaking.

He was also certain that the attraction was mutual, at least to some extent. She had tried to maintain tight control over her reaction to him earlier in the evening, his body aligned with hers in that quiet hallway, but she had vibrated with longing and all Castle had wanted to do was absorb it. The biggest problem now was that she had spent the last couple of hours away from him, probably doing everything she could to negate the intensity of the few minutes they had shared. Beckett worked hard to stay locked down; he just wanted to set her free. But first he had to get inside.

The elevator doors finally opened and he nearly tripped over his own eagerness to reach her apartment. Pausing for the briefest of insecure moments, he knocked and waited.

"Hi, Castle." The door was wide open, her expression anything but. As expected, Beckett was carefully schooling her features, giving no indication of what she might be thinking. Still, she stepped aside and allowed him to enter, and he hurried past before she could change her mind.

While he had been playing the part of hot-shot bestselling novelist, she had changed from seductive siren to delightfully domestic; still his muse nonetheless. Her pajama shorts and tank top belied the cool fall weather, but he was admittedly thrilled to be treated to the view of her smooth skin. Castle removed his jacket and laid it across the back of a chair, while Beckett made her way into the kitchen.

"Would you like something to drink?"

"Whatever you're having would be great. Thanks."

He stood there awkwardly, unsure of whether to help or wander aimlessly around her living room. She pulled a couple of wine glasses from the cupboard and laughed. "Castle, go sit down. You're making me nervous."

A minute later, settled on the couch, he smiled up at her when she handed him his wine. She sat down next to him, long legs curled under her body, and raised the glass to her lips.

"Wait, Beckett, we have to toast."

She raised one perfect eyebrow. "To what?"

Honestly, he didn't know. Well, he had a few ideas, but had to tread lightly; his heart rate was tapping out an insistent reminder that this was too important to screw up. Castle took a deep breath.

"To a successful launch."

And just like that, the tension was back, both of them able to see past the obvious reference to Heat Wave. He had no doubt that her blown pupils were mirrors of his own, their chests rising and falling to a shared song. Somehow their glasses came together with a timid clink, and they both took a few seconds to sip their wine and find their courage.

Swallowing the warm liquid, and nearly choking on desire, Castle set his glass on the coffee table and reached for hers. Beckett let it go, but flinched when his finger brushed over hers; leaving the glass with its twin, he turned back to her and was overwhelmed by the conflicting arousal and fear written all over her face.

"Castle, what are we doing?"

He shook his head slowly, unsure of how to respond, words failing him for the first time in years. He brought his hand up to tuck an errant curl behind her ear, then cradled the side of her face in his palm. Beckett leaned into his touch, and he closed the distance between them; their eyes were shut by the time he gently brushed his lips against hers.

The kiss was so much softer than Castle had ever imagined it. Since her exasperated interrogation of him months earlier, he had been convinced that unrestrained passion would eventually have them pressed up against a wall, desperately biting and clawing at each other, clothes hardly off as they became one. Instead, the kiss was so slow that he could focus on her warm breath, the hint of wine, the tenderness of her mouth on his.

This was better.

Careful not to spook her, Castle barely opened his mouth, just enough to drink from her lower lip while his hand moved to the back of her head. To his surprise, Beckett grabbed the front of his shirt and held on, flicking the tip of her tongue against him in a silent request. He had no intention of denying her anything and easily allowed her access to whatever she wanted. As smoothly as her tongue explored the depths of his mouth, her legs unfolded and repositioned themselves on either side of his, her knees tight against his hips.

Their bodies were nearly welded together, the fabric between them becoming a nuisance, but the kiss was still exquisitely reverent. The heat of their tongues sliding softly against each other was enough to satisfy every fantasy; the shaky moan from deep in her throat was enough to give him a million more. Beckett rocked against him, obviously aware of how much he wanted her, but never broke the kiss. Amazing as it was, Castle was ready for more and grabbed a fistful of her hair, gently pulling her head back to expose her long neck.

Starting just above her collarbone, he licked his way toward her ear, sucking lightly on the sensitive spot there and drawing a sound from her that made his hips thrust without his permission. As his mouth travelled back down, he hooked a finger through the strap of her tank top and dragged it off her shoulder, giving him miles of uninterrupted skin to kiss. Beckett's hands had found the back of his neck, and she mindlessly teased the short hair there.

Suddenly, as if she finally realized that she was being abnormally passive, she nudged his head away and pushed him into the cushions so that she could hurriedly unbutton his shirt. Castle let his head fall back, appreciating the feeling of her nimble fingers dancing down his chest. When she tugged the shirt free of his waistband, he leaned forward and helped her remove it completely, watching it sail onto the floor without a care. Caught up in the frenzy, he gripped the hem of her tank top and yanked it over her head in one fluid motion. Both of them eager for the skin-to-skin contact, they wrapped their arms around each other and met for another sensual kiss, only stopping when Beckett mumbled into his mouth.

"Castle…bedroom."

Unwilling to completely separate, they stumbled through her living room and around the corner to her bedroom door, the lack of grace excused by unapologetic need. He kicked his shoes off somewhere along the way, his belt not far behind them. By the time they were standing next to her bed, her hands were busy unfastening his pants; she removed them, his boxers, and socks within seconds. Excited to return the favor, he dragged her shorts over the curve of her ass and let them fall to the floor.

He kissed her again, only stopping long enough for them to get situated in the middle of the bed, Beckett on her back, Castle pressed against her side. While they continued to share one breath, he let his hand journey across her body. She shuddered when he cupped her breast, the pad of his thumb playing against her already erect nipple. He kept moving, floating along the smooth skin of her stomach, squeezing at the flare of her hip, eventually catching her gasp in his mouth when he reached the juncture of her thighs. One adventurous fingertip dipped into her arousal.

"You're wet."

It might have been the most unnecessary observation of the night, but she just smiled against his lips. "Have been for hours."

Castle groaned into her mouth, his body questioning his languid pace, but he refused to speed up now. If he were to die tomorrow, he had to know that he had spent as much time as possible with the gorgeous creature below him. "Beckett, will you let me taste you?"

Her dark eyes widened as he pulled back to await her answer, his hand still pressed against her heat. Then she nodded.

He slid down her body, settling himself between her legs. Part of him wished she still had that amazing blue dress on, the material bunched up around her waist, but Castle couldn't possibly be upset with the bare skin displayed before him. He eased her legs further apart and held her open with both hands, looking up at her for confirmation that she was still okay. She held his eye contact for a moment, giving him a shy smile and another small nod.

That was all he needed. Lowering his head, he placed a soft kiss against her swollen clit before taking it into his mouth and sucking softly. When Beckett started to squirm, he pulled away and nipped at her inner thighs, then quickly returned to run the tip of his tongue along her center. His senses were fighting for dominance, enveloped in her musky scent and sipping her unique tang. Castle rubbed his face against her, the stubble teasing her sensitive skin and causing her to push into him for more pressure. Unable to resist the pooling desire, he began to fuck her with his tongue, plunging as deep as possible and relishing her flavor.

Her body arched into him, her breathing becoming more erratic. Castle moved one hand up to her abdomen to carefully hold her down, and used his other hand to keep her open for him. Knowing she was getting close, he moved back to her clit; when she palmed the back of his head to keep him in place, his instincts were confirmed. He alternated between sucking and licking the sensitive nub, taking it into his mouth completely and humming in anticipation.

Beckett's entire body was tightening, her legs threatening to do permanent damage to his head, but he was relentless. She begged, prayed, and cursed, his name an invocation of something even bigger than himself. Desperate to push her over the edge to which she was clinging, he applied just a bit more force to her clit and made her fall.

Castle brought her down, caressing her shaking legs with his hands and mouth. As her breathing returned to normal, he wiped the evidence of her orgasm from his face, and she tugged him toward her for a kiss. Knowing that she could taste herself on his lips made him want her even more, if that was even possible, but he gave her everything he had. Then Beckett reached down and began to stroke him, guiding his tip through her folds, obviously ready for one final step. He looked up at her again, needing to be sure.

"Please, Castle."

He glided into her with one long stroke, filling her completely and drawing a relieved sigh from both of them. Castle stayed there for several seconds, neither of them moving, letting the feeling of being joined wash over them like a baptismal stream. When the emotion crested, he slid almost completely out of her body, before burying himself deep inside once again. Establishing a steady rhythm, he rocked his hips into her repeatedly, encouraged by the primal sounds being pulled from her mouth and the nails dug deep in his back.

The slapping echoes of their bodies were the cymbals of a pornographic band, keeping the beat of something only they could hear. Beckett wrapped her long legs around his waist to pull him closer, meeting him thrust for thrust and encouraging him to be harder…faster…deeper…more. He knew he wouldn't be able to wait much longer, but needed her to come one more time before he did. Castle worked his hand between their sweat-slicked bodies and unerringly found her clit. Making tiny circles with the tip of his finger, he crashed his mouth into hers for one last kiss before they both went flying.

Her muscles were already fluttering and he raised himself off her enough to make eye contact, eager to watch her face at the moment she clenched around him.

"Let go for me, Beckett. I want to feel you come while I'm inside you."

Apparently that was all it took. She arched once more and cried out, tightening around his length and pulling him deeper than he could have imagined. He was sure to have crescent-shaped marks on his shoulder blades, but they were the furthest thing from his mind as he leaned forward and whispered a prayer of his own in her ear, her name a breathless supplication. Castle spilled insider her and struggled to keep himself from collapsing against her body.

When he could move without endangering either of them, he slipped out of her and rolled to the side. His eyes were closed and he was surprised when she reached for his hand, squeezing it comfortingly. Still, he didn't turn to her until she spoke.

"You know I didn't do any of this because I'm trying to keep you at the precinct."

Castle smiled. "I know. And you should be aware that I'd gladly be here whether I'm writing about a certain British spy or not."

"Does that mean that you've made a decision?" Her lower lip was firmly tucked between her teeth and he knew she was more unsure than she wanted to be.

He nodded against her pillow. "Yes."

Before she could ask any more, he leaned forward and kissed her reassuringly.

"I already told Paula to turn down the offer. I'm not done with Nikki Heat."

As always, I'd love to hear your thoughts!