A/N: This chapter is M-rated.

Disclaimer: Not mine.

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"Castle?"

"Yeah." Idiot. Yeah? She wasn't questioning who he is; she's wondering why he's crawling around outside of her door.

He stands from his squatting position, nervous and bitter and angry…and why the hell does she have to be so gorgeous? "I'm returning your key. Keys," he corrects. "This one fell out." He looks at the shiny key pressed up against the dull one. His heart thuds knowing that she replaced the one she gave him. Why would she, if he wasn't supposed to keep it long-term?

None of that really matters, though—her motivations of the last few weeks—because she's done with him now. He's got to keep reminding himself of that.

"Oh." She's quiet. And this is a huge mistake. Massive. He needs to never see her again, not make excuses to flick through memories…and get caught in the process. She looks sad and it's probably because he's a dejected mess. But, he doesn't want her pity, damn it. "I thought you were the delivery guy." She holds up her wallet, smiles a little.

He doesn't care. And certainly doesn't want her resplendent smile.

"Here." He thrusts the keys at her. He's tearing up again. No, no, no. "Take them. I need to go." If he were slightly pettier, he'd just toss them at her, but damn if he doesn't throw a pitiful excuse of a temper tantrum. Instead, he defaults to crying like a baby. Macho. But he's not going to cry now.

She takes the keys from him, and it's electric when their fingers slide against each other. He pulls back as if burned. He has been burned, and she has the audacity to appear hurt by his jerky withdrawal.

"Don't go yet." He's already facing away, and when he turns back to her, she looks remorseful and guilt-ridden. "I, uh, have something of yours, too." She says it too quickly, too explanatorily, and he realizes it's because she doesn't want to give him any false hope. He wants to tell her that all of his hope is gone, so she can say whatever she pleases—he won't get the wrong impression.

"Is it my heart?" He asks, bitterly. "You gave that back earlier today, Beckett."

She flinches, swallows hard, but doesn't respond. Spinning, she stalks into her apartment towards the vicinity of her bedroom, leaves the door hanging open in her wake.

He's pretty sure it would be a good idea to high tail it out it out of here now. There's nothing she has that he wants back; nothing being returned to his possession is worth this humiliation. But he fears that if he doesn't stay now, he'll be forced to encounter her again, wholly unprepared. And as much as he wants to be in her presence every single day for the rest of his life, that's evidently not in the cards now, and seeing her is too excruciating to keep enduring.

This is it, he realizes. This will most likely be the last time he sees her, interacts with her. Maybe, sometime in this big city, he'll pass her on the street, see her across a crowded room; he'll wave cordially, pretend like it doesn't affect him, like his heart isn't breaking all over again.

He hears someone clear their throat behind him and he sees Kate's elderly neighbor peeking out his cracked door to smile and wave his way, giving him a wrinkled thumbs up with a wink. A blush crawls up Castle's neck when he remembers Kate telling him that her neighbor had pulled her close in the elevator the other day and told her "I used to have a head of hair like that boyfriend of yours. My wife used to like to run her fingers through, too. You women. He looks like he knows how to treat a woman, if you know what I mean." Rick didn't know what he meant until Kate reminded him that between peep holes and hearing aids, there isn't a whole lot of privacy in her hallway. They never came up with the exact, um, interaction old Mr. Hinkly witnessed, but they had been handsy enough times before entering her apartment to have the necessity to be embarrassed.

He sighs, waves back, then shuffles over the threshold and clicks the door shut behind him. Mr. Hinkly isn't getting a show today, but Castle doesn't want an audience for his final goodbye either.

He knocks his head back into the closed door, slumps against it, waiting on Kate's return. It smells faintly of burning candles in the room, and he wonders if she had been taking a bath. Her hair wasn't damp, but sometimes she likes to put it up, not let it get wet.

Tonight, she's wearing the robe that he had been adamant about being nothing more than a tease; on the surface it looks fully functional—soft, absorbent terrycloth—then, upon further (lower) inspection, you discover that it barely covers the swell of her rear end, swings at the most supple parts of her thighs. And in those weeks in and out of her apartment and in and out of her bed, it made his stomach flutter and his groin tighten when he saw her in it.

Like now.

As much as he's trying to ignore all of that at the present moment(he did a spectacular job earlier, if he says so himself), thinking about the delicious things she did to him each time she slid the material from her body, has his body betraying him once again.

Castle's hand tightens on her doorknob, but before he can twist it, he feels the energy shift, and she reappears in the room. She's holding…a tee shirt? Oh. His shirt. The light gray one she "stole" because it was soft and comfy and smelled like him (her words).

"I'm sorry," she says. "I was going to wash it before I returned it. But, well—."

"I'm here now? And it'll just be easier to get this over with, so you don't have to see me again," he finishes for her.

"Castle—"

"Hey, no, I completely agree." He lifts his palms in supplication. "But, I don't want that shirt." There is no way he'd ever wear it again, the reminder would conjure up too vivid of memories. "Keep it, trash it, burn it, whatever."

"It's a nice shirt." She fingers the material, almost wistfully.

"So you said. I remember." He's trying to tell her with his eyes that her resistance is futile. He's not taking the damn thing with him. Why is she doing this, making this more difficult? Doesn't she know this is killing him? She says she cares about him (oh, the famous words of champion heartbreakers); if that's true, she needs to be a little less sadistic in her approach to letting him go.

He plucks the shirt from her hands, tosses it in the basket by her door. Watching her toy with it, picturing her in it, is ruining him. He longs for answers.

"Is there someone else, Kate?" Castle doesn't like how the words sound, definitely doesn't really want a reply, but needs one. It's the only thing that makes any sense in his mind right now, and images of her slipping off—and slipping on—another man's clothes are blinking in his mind and have his insides roiling spitefully.

"What?"

"Another man. Is that why we're not doing this anymore?"

"Jesus, is that what you really think?" She's angry. Good. Because so is he.

"Maybe. Because you won't give me a clue as to what I did wrong."

"You didn't do anything wrong, Castle. I told you that."

"That's a line of bullshit, Kate."

"You need to go." She reaches around him for the door knob, but he shifts to stand in front of it.

"Please tell me," he pleads, releasing some of the fury in his tone.

"I can't."

"What does that even mean? You can't." He uses air quotes to mock her words, his gestures sharp and jerky. "If it's because you don't want to hurt my feelings, it's a little late for that."

"I'm not doing this." A step backwards is halted by his hand on her wrist. He doesn't mean to touch her, feels out of line, but can't help it.

"Was I too clingy—spent too much time here? I can stop." His tone softens and he feels pathetic, begging her like this, but his words aren't governable any longer; he can't shut them off. "I've never been like this in a relationship, Kate. I'll let you decide how much time we spend together. I can back off."

"It's not that, Rick." She shakes her head, tugs on her wrist, but he's not letting go. "You were—no, no, I don't want to talk about this. I can't."

"Was it the sex? Not good enough?" He lets go of her wrist, slides his palm to her thigh, tugs her towards him. His brain is screaming that this isn't a great idea. Despite her gasp, she concedes. Her eyes are closed, but her body is pressed limply against his. She's not fighting him, but he can see in her face that she's fighting something. "I asked you to tell me what you liked. You said I was doing everything perfectly."

"You know it's not that."

"I don't know anything!" He's loud and he shocks himself a little as he kicks back against her door and the echo of it reverberates around the room. Ah, so Mr. Hinkly might get a show tonight after all. Not the fun kind.

Her cheeks are wet; it's obvious that his little outburst scared her. He wants to apologize, but what little pride he has left won't allow it. Before he can war with himself anymore, her mouth is on his, her own apologies rasping against his teeth. He groans and spins them, crashes her back into the hard surface he was just crowded against. It's too familiar, too good. Apologies and kisses and doors. But, this doesn't feel new and optimistic. She's telling him that he needs to leave against his tongue, and the unfair game she's playing—plus, the way his body doesn't second guess a reaction to it—is making him livid again.

He seizes her hips in his hands, snakes his fingers around to her ass, pulls her up to slide a knee between her legs. She bites down on his lip, hard and satisfying, the lick of pain spiking his arousal.

"You're bare under here," he notices aloud, fingers skimming the crease of her thigh, where her panties would normally settle. "And you were going to answer the door like this?" He grumbles the complaint into her mouth. "A little extra tip for the delivery boy?"

She strikes his chest forcefully. "Don't be a jerk." She pushes herself away, slides down his leg, and tries to get her footing. But he pulls her back to him, rocks her against his thigh. Her instincts take over as she moves quicker against the rough denim. He can see arousal clouding her eyes—likes the implication—but there's more clarity there, too, a sense of the fire they're playing with.

"Any man in his right mind, who saw you in this—," he fingers the terrycloth for a moment before sliding his palm high on her inner thigh, "—would want to touch you. Make you his. Right here against your door."

"God, Castle. We shouldn't—"

"We should." The distance is a short one for his fingers to reach their destination. He lowers his thigh enough to inch his hand between his leg and her undulant body, his digits slicking inside her easily.

Sexy hums and moans and whimpers that are coming from her lips are going to be his undoing. How is he supposed to live without this, her? When her spine stiffens and arms go slack around his shoulders, he knows she's close, has to wrap an arm fully around her back to steady her. A solid press of his thumb has her pulsing around his curling fingers and collapsing against his chest.

"Do you come that fast with every man you're with?" He bites down on her neck and feels her clench down on his digits even harder. He pumps through the tightness, hard jerks against her.

"There's no one else, Castle. No, no," she's keening into his shoulder, still throwing her hips against his hand.

"Then why are you doing this to us?" He slides the zipper on her duster down, pulls it to the side to latch his mouth onto her nipple.

"Castle, don't," she breaths out, determinedly enough to make him stay his ministrations.

He rises to meet her eyes, but they're still screwed shut, head rocking side to side against her door. He pulls his hand from beneath her robe, swipes his damp fingers along her thigh. He tries to straighten his posture, but one of her hands is pinned tightly around his neck, the other fisted in his shirt, and he can't fully pull away. "Don't what, Kate?"

"I don't know, I don't know," she cries, slides her hands to the front of his pants and begins undoing them. His lids slam shut when she reaches inside the slackened material to stroke him. "We can't do this." Contradicting herself, she coils her warm palm around his hot flesh.

"Then you need to stop," he spits venomously, gripping her forearms forcefully. "You need to let me go. Or don't. You can't have both." He means both literally and figuratively—she can't keep him hanging by a thread like this.

"I'm not sure how to let you go, Castle. I'm trying." She's crying and panting and he's an emotional basket-case because of everything they're doing and not doing.

He releases her arms with a stuttering sigh, and moves to fasten his jeans. But, her hands are shooing his out of the way as she tugs the denim and boxers lower on his hips and resumes her caresses, rough and too stimulating. "Finish, Castle," she prompts.

Oh. That's what this is? What, a pity hand job? One last good time?

No. No. "If I finish," he growls, "it's going to be inside you." His teeth scrape against the column of her throat as he makes his way to her mouth. He sinks his tongue past her lips and she sucks it into her mouth, slanting to take him deeper.

He raises her robe, bunches his own shirt up his chest, until their bare stomachs touch, her hands trapped between them. "Tell me to stop, Kate," he beseeches, waiting for her inevitable withdrawal.

"No." It's barely audible, but reverberates deafeningly in his ears. The slow grind against him is all he needs to take her knee in hand and roughly pull it to his waist, opening her up to him. He pushes into her fiercely, shudders against the incredible feel of sinking into her. She bellows deeply at the sharp intrusion and claws at his shoulders, climbing against his body.

This should be fast and furious, should punish her for saying she doesn't want him, but opposing that with her every touch and sigh and, oh, movement against him.

He slides her further up the door until her other leg wraps around him instinctively, until he's her only support. When his forehead drops to hers, she sniffles, smooths her fingers down his cheek, lets them linger there.

"I'm not sorry for loving you, Kate."

"Move." Her heels dig into him, spurring him on. She's trying to disregard the intimacy he's lending to the moment. He pulls out of her slowly, then pushes back into her, rattling the solid door.

"You can't ignore this," he reminds, with a strong rock against her. She doesn't want him to talk so she takes his mouth, uses her tongue to blanket his voice. That's fine. He'll kiss her; he can show her what they have that way too. He sandwiches her tightly between him and the wood at her back, uses a newly freed hand to clutch her hair, tilt her head, and dominate the intensity of their kiss.

She hums into his mouth, sways into him, groans in frustration when she can't get leverage. He laughs into her neck, sucks that spot that makes her crazy, and she grumbles and bucks against him. Giving into her silent demand, he stills her, slides his palms beneath her thighs and gives her a strong press of his hips. A sobbing huff of pleasure gurgles up from her throat and it only serves to spur him on. His knees are protesting when she straightens sharply—then wilts with desire—sagging heavily with her orgasm.

A quick knock on the door—a bit of a tune in its cadence—has her dropping a leg to the floor. He's almost there, almost there, and out of want, or misguided need for a finale, or awesome kindness, she bounces on the ball of her foot, aiding in the breathtaking sensations that are overcoming him. "Shhh," she breathes into his mouth as his rhythm falters and he's so close—and he thoroughly enjoys that she knows this. She swallows his moan when he lurches against her, pitching his hips messily until he spasms inside her.

"That was incredible."

"That—that was a mistake," she pants as she slides down his body. She's combing her fingers through her hair, zipping her robe, and futilely tugging at the hem to give it more length.

"I'm finding it hard to decipher whether there's any truth in your lies, Kate."

Her eyes flash to his, a warning that he ignores while he tucks back into his jeans and gets himself presentable before gesturing for her to open the door.

A pimply faced teen is holding a Giovanni's pizza, and Castle can't help but grin. She knew that was their planned dinner—pre day-from-hell—and subconsciously or not, she added some sentimentality by ordering the same without him.

Her body just told him that it still wanted him. And this little tidbit of romanticism tells him that she misses him. So, he has to figure out what the hell is going on.

He's not giving up this time.

Kate has the decency to appear embarrassed, and he has the decorum to not say 'I told you so' as the boy at the door eyes her head-to-toe, lingering at all the pubescent points of interest.

Castle clears his throat menacingly and the young deliverer thrusts the pizza out, willing someone to grab it, red heat climbing up his face. Yeah, kid, eyes off.

Beckett, with shaky hands, is fishing through her wallet and finally pulls the right bills out, slides them across the box as she grabs the corners of it and tells him to keep the change.

While her hands are full of pizza, Castle takes the opportunity to lay his mouth on hers, a quick pull of lips. "This isn't over," he whispers before squeezing between the cardboard and the doorframe. "If you hurry, I'll hold the elevator for you," he offers as he backs down the hallway, pointing to the young man, who looks scared but acquiescing. The teen thanks Kate, and scurries towards him.

Kate is still dazed, he can tell, when she leans half out of her apartment, watching him. He waves through the closing panels and calls out to her. "I'll see you tomorrow."

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A/N: Thanks.