Summary: This is an alt-S3 story and explores how things would/could have gone differently if there were not significant others in the way. This will be told through a series of one-shots (or maybe two or three-shots depending on the episode) that will (most likely) not be related. (If they do relate to a previous chapter, that will be notated in the A/N at the beginning of the chapter.)

Nikki Heat

It isn't right. She's the wrong Nikki. No, wait, wrong Beckett. No, not even that, she's not Beckett at all. Castle drops the clothing box both out of shock and as a way to get his hands free so he can get his hands on her. Get his hands on her to get her off of him, that is. He can't close his eyes, can't give himself over to this because it isn't right.

And he wouldn't have seen the devastation on Kate's face if he had closed them.

The elevator doors close too quickly for him to do anything about it, his movement impeded by the actress twining herself around him. "Natalie, stop," he says, firmly gripping her biceps and holding her away from him.

"You guys are together, aren't you?" She poses it as a question but there's more than a little bit of supposed knowing in her voice.

"No," he corrects as he hits the button for the upcoming floor.

"Then why are you so desperate to go explain yourself?"

The elevator dings and the doors slide open. "It's complicated," he sputters as he dashes out of the car and up the stairs.

It's only complicated because he doesn't know what she wants. He's tried to surreptitiously ask her at least a dozen times what they were, if they could be more. He's either being too subtle or she doesn't want to talk about it.

But that look on her face said a lot and the pain in her eyes is too hard to ignore. So, yeah, he needs to explain himself.

Her desk is neatly organized, paperwork lined up in her end-of-the-day stacks, computer shut down. He just left, how could she be gone?

"Dude, what did you do?" Esposito asks him as he comes out of the break room.

"What are you talking about?"

"She just jetted out of here and she was not happy, so what'd you do?"

"Which way did she go?"

Esposito narrows his eyes at him. "Why?"

Castle huffs exasperatedly, completely out of patience for the overprotective brother routine right now. "Because I think I'm the reason she's unhappy and I'd like to fix it," he says in a rush, hoping that the truth will be the quickest way to the information he's looking for.

It works, Esposito pointing wordlessly towards the back hallway, clearly surprised that Castle admitted it so easily but the writer has no time to explain. He rushes down the hallway, the stairs, races into the garage and to her cruiser's designated spot -

Only to find it empty.

He wants to laugh or yell in frustration or drop to the concrete in defeat. But he doesn't know what she wants so he doesn't know which is the appropriate reaction. He's tempted to make the grand gesture and show up at her door, beg her to let him explain. But he has no idea why he should.

He settles for going home. He hates it.

He brings her a cup of coffee the next morning because it's normal and he thinks they need some of that right now. That she needs the reminder that just because Natalie Rhodes has turned their world on its side, he's still here. She gives him an icy glare when he offers the cup to her but he doesn't waver, doesn't shrink his hand back.

"Is that for me or for the fictional version of me? Or have you already taken care of her this morning?"

"And what is that supposed to mean?" He asks it as a challenge, wondering if she'll actually admit that she saw what he knows she saw.

He doesn't have the chance to find out as a crying Jenny O'Malley rushes past them.

He's in the break room to give Ryan some space to call Jenny and, yes, okay, to hide from Beckett and Creepy Beckett. He's distracted, checking an email on his phone, but raises his head when the one of the doors click closed, watches Kate cross the room to pull the other door closed as well before she turns to face him.

"You didn't sleep with her," she states without preamble.

He pockets his phone, shaking his head as he does. "No, I did not."

She folds her arms under her breasts, her eyebrows knitting together in a move that he knows means that she can't make sense of the evidence before her. "Why?"

He shrugs. "A fictional character that I wrote based on you, played by Natalie Rhodes? It's just way too meta." It's not untrue but it's not the main reason. The reason that she's probably looking for him to say.

She fixes him with a gaze so intense that it feels as though she's looking right though him. He's seen her stare down plenty of suspects, seen her use the silence to get them to reveal their secrets but this isn't that. It feels more intimate, like she's looking for his secrets rather than coaxing them out, like she's fishing through his heart to find the truth. He'll let her look all she wants but all she really has to do is ask.

They're silent for a long moment, her searching, him waiting. She opens her mouth like she's about to speak when there's a timid knock at the door. They turn their heads to find Ryan on other side of the glass, his eyes broadcasting apology. Beckett waves an arm for him to enter and Castle has to smother a laugh as the man gingerly eases the door open and takes a tentative step into the room.

"Just wanted to let you know that the three other clients of Stacy's that have filed for divorce alibi out and Espo just got back," he says in a rush, as if he's afraid she'll kick him out if he pauses too long.

"He find anything on Greta Morgan?"

"Yeah. Found something pretty interesting at the Meritage Hotel," Esposito answers as he steps up beside his partner. They wait a beat but he doesn't elaborate.

"What?" Beckett snaps out.

"Greta Morgan." He jerks his chin out the window where the woman in question is being escorted across the bullpen to interrogation.

"Good work," she tells them, the men nodding at her before turning to leave.

Her gaze swings back to Castle, that searching look back on her face but this time she doesn't wait to talk. "We're not done here. I believe your reasoning but that's not the whole answer, is it?"

He hesitates, another half-truth on his tongue but how can he expect her to talk about what she wants when he doesn't always make it clear? He forgoes any subtext he might have said in favor of a single syllable. "No." He's gravely serious, knows that that alone should tell her plenty but he can't completely reign in the lust in his tone, trying instead to keep it at a work acceptable level. He might have failed on that aspect though.

Because the searching look is gone, replaced with some shock at his boldness, her eyes darkening more than a little. "That's what I thought," she breathes. She drops her eyes to the floor, clears her throat and leaves the room to go do her job.

The congratulations for Kevin and Jenny have long passed, the couple escaping home for their own private celebration once a round of handshakes and hugs was passed around. Castle's proud of the man, of his perseverance to make sure that his love understood what was going on.

Which is why he's still at the precinct, sitting in his chair, watching Kate finish paperwork. He's been inspired and is now waiting for his own chance to explain his interaction with the starlet. Because it seems that she does want to hear it and if he wants anything close to what the future Mr. and Mrs. Ryan have, he's willing to put in the work.

She raises her coffee cup to her lips, frowning when she finds it empty but his hand is right there offering to take it from her but she doesn't relinquish it to him. "Go home, Castle. Everyone else has."

"Uh-uh," her shakes in head in dismissal, "You said we're not done, so I'm still here."

"I didn't mean it has to be tonight." She sighs, sitting back in her chair.

He stands and plucks the mug from her hand. "And put it off for another week? Another month? I'm tired of that, I'm beyond tired of that." He doesn't give her a chance to respond, just heads into the break room and sets about refilling her drink. He's layering the milk over the espresso when she appears at the doorway, accepts the coffee he offers her, holding the mug to her chest like a shield.

"You didn't sleep with her," she states in an echo of their previous conversation. He leans back against the counter, shaking his head. "Why?"

No evasion this time. "She wasn't you."

She takes a deep breath, seems to be gathering herself, and moves to take a seat at one of the tall bistro tables. He stays where he is, knows that crowding her isn't at all the right move right now but wants to be in her proximity, wants to take her hand while she rides the tide of emotion he can see in her eyes at his simple sounding declaration.

Because they're just three small words but together they're unmaking her world.

"I saw you," he says into the silence. Her face is still oriented towards the table, but her eyes slide over to him, not quite meeting his eyes. "Before the elevator door closed," he clarifies. "I got out at the next floor but you were gone before I could get back up here."

"Why'd you come back?" she asks softly.

"To explain myself."

"Castle, you didn't have to-"she protests weakly.

"I did," he states decisively, cutting off the end of her sentence. He has her full attention now and she shifts in the chair, facing him fully. "Because I saw you. You were upset. And I needed to explain that she kissed me. That she insisted she was Nikki and I was Rook and she needed to sleep with me to be the character. And she can be Nikki all she wants but she wasn't you."

She nods, chewing on in the inside of her lip in thought for a moment. "I've heard you ask me. When you've tried to figure out what this is, what we are? I've heard you."

He suspected as much but hearing her admit it stings. "Why didn't you answer?"

"Because the last time I tried to talk to you about anything regarding…us," she hesitates on the last word but it's one of the most beautiful things to ever fall past her lips, "you left with your ex-wife for the summer."

He feels his brow contort in confusion. "What were you really going to say that day?"

"I was going to accept your invitation." It's exactly what he assumed she was about to say but it still lands like a punch to the gut.

"So why the hesitation now?"

"I keep waiting for you to move on again."

Is she crazy? Move on to what? "I can't. No one's you, Kate. Not Gina, certainly not Natalie Rhodes, though she put in a good effort." That earns him an eye roll and a smile tugs the corners of his lips up for a moment. "But I wasn't moving on last summer. I was trying to cover a wound."

"Did it work?"

"Not even a little."

She nods and it looks like understanding, a pleased smile gracing her mouth. "So what now?" she asks.

"Go out with me," he says boldly, not even bothering to pose it as a question.

Her smile widens, her eyes twinkling. "When?"

"Tomorrow night. Case is done, you're not on call, it's perfect." She doesn't even bat an eye that he has her rotation memorized.

"Perfect," she echoes, sliding off the chair. "Are you sure we're not past a first date though?"

"Maybe," he concedes, pushing off the counter. "But it's classic. Nervously picking out clothes, flowers when I pick you up, flirting over dinner, kiss at the front door. Might be refreshing to do something in order for once."

"But isn't being unconventional kind of our thing?" she teases, stepping closer to him.

"Never hurts to try something new."

"Speaking of that, I do have one problem with your plan." He looks at her questioningly and she continues, "Do I really have to wait until tomorrow to kiss you?"

"Oh. Well, I guess that can be moved up in the timetable."

She doesn't wait until he's done talking, her arms twining around his neck, her lips pressed to his as soon as he says the last word. His arms slide around her waist, hands splayed wide at her back, bodies flush from thigh to chest, her mouth soft and warm. It ends far sooner than he would like, her hands moving to cradle his face as she pulls back.

"This doesn't mean I have to take that off tomorrow's plan, does it?" he asks, a little breathless.

"You better not," she answers, leaning in for another brief brush of lips. "Now go home. I'll see you tomorrow."

He reluctantly releases his hold on her, lets his hands linger longer than might be strictly necessary, dropping them only when she gives him an "I know what you're doing" look.

"7 okay?"

"It's perfect," she replies, a brilliant smile lighting up her face.

"Until tomorrow then."

"Tomorrow."

This time, the elevator doors close on her smiling broadly at him and he finds that he wants to stop the car and get out early for an entirely different reason than last time.

But he goes home and doesn't hate it this time. Because they have tomorrow.

I'd love to know what you think.

A/N: If anyone started this story thinking that it was something other than "all the ways that they could have hooked up," I apologize, it's not. It's totally all the ways that they could have hooked up. And especially now, this far into the season, I'm having a hard time coming up with reasons why they shouldn't be together. So, basically, what I'm saying is, expect a lot more kissing from here on out. I'm sure plenty of you are fine with that.