BECAUSE PRETTY PRINCESS PUG MADE ME DO IT. Okay I didn't exactly complain. Um, yes anyway, as Vallie says, this is speculation (wishful thinking) for the season finale. SO SPOILERS. THERE ARE SPOILERS HERE FOR THE HUMAN FACTOR AND WATERSHED. BE WARNED. It's probably going to go nothing like this, but I firmly believe that Castle and Beckett are not going to break up. They've fought too hard to get to this point to let this come between them. THEY'LL BE FINE, OKAY. AND IF NOT… well, let's just say Marlowe may suddenly disappear.

Disclaimer: my screen went blank and wouldn't come back and I hadn't saved and I thought I'd lost all my work I almost cried.

He doesn't think Kate noticed him snooping around her address book. Or if she did, she didn't question it. He thinks she's just come to term with the fact he snoops. And she doesn't seem to care. She's accepted him into her life as easily as one accepts a new pair of shoes. But he wants more. He wants her in his spaces all the time, every day of every month of every year. And he doesn't want to do this like he did with Meredith or Gina, doesn't want it to be spur of the moment, or panicked because she was pregnant. He wants this to be planned. To do it properly. And to do that, he needs the address book. He needs to work out where the hell in New York Jim Beckett lives.

He's nervous about this. He is, he's absolutely terrified because he knows that right now Kate is doubting his ability to commit. Truth be told, he was doubting himself too. After two failed marriages he's not particularly confident in his marriage keeping skills. But he's too scared about losing Kate. More scared about losing Kate because she wants something more and it's something that he can't give her. Except he can, and he will. He just needs to have faith in them. Kate has so much faith in them. They're her own brand of magic.

So, one afternoon when Kate is busy at the precinct and he's made the excuse of needing to write and he's snuck out for the afternoon. He's nervous. He's horribly, horribly nervous and his palms are sweaty and he can't keep his knees from jiggling, and he's pretty sure the taxi driver thinks he's on drugs. But whatever. Doesn't matter. He just needs to ask Jim a question. One question. How hard is asking one question? Not hard at all. Nine words. He's a writer. He can make nine words, easy peasy.

Jim opens his door like he was always expecting him, like he knows that one day Castle was going to turn up at his doorstep with this very question in mind. Jims apartment is not particularly how he imagined it. He never imagined the man as a collector of all things strange and wonderful, not like Kate, but he sees a lot of Kate's place here. The style of art, the bric-a-brac on the shelves. They've both managed to make it their own, both fundamentally independent of each other, but he could imagine Kate here. Arranging, dusting, finding some other wacky ceramic duck that seems to have taken up most of the mantle above the fire place. Jim gestures to a sofa, and Castle sits, hands folded in his lap. He feels like he's been sent to the principal's office. Only this is scarier. This is so much scarier. This is his whole life.

"What can I help you with, Rick?" he asks, and there's a knowing twinkle in his eye.

"It's Kate. About Kate. And me. Both of us. I – she doesn't think I want to commit. That I'm too scared. And she's right, really. I'm terrified of screwing it up. I've already been divorced twice. I don't want to do that again. And if I don't get married then I can't. I can't screw it up. But she – we had a case. Mixed up with the FBI, and this agent got an idea into her head and now she's been offered a job. And I'm happy for her. I am. It's just… the job is in Washington. And she said that we could make it work. It's not like I have to be in New York to write, but she's moving there. She's going to move there, and I can't just pack up and move with her. My daughter is here, I can't leave my mother alone and she'd never cope with living in Washington. She belongs in New York."

Jim takes all of this in with a quiet certainty that makes Castle feel slightly uneasy. Those blue eyes. So completely different to Kate's golden brown, but yet… there's something about them. It's not the colour, or the shape, but the way they see the world. The way they look at him. "You think you'd mess it up." Statement, not a question. "You think that if you marry her then it's going to end in divorce, just like all the other times."

"I can't make it work. I try, but I can't. And I love her. I do, she drives me crazy and she's frustrating and maddening, but I love her and I want to spend the rest of my life with her… but I don't want to jinx it. If I marry her, I don't want it to lead to disaster."

Jim takes the opposite sofa, leans forward, elbows on his knees. "Katie doesn't give her heart to just anyone. You know that. It takes time and work and patience to get to know her. I can understand your concerns, but you've got to see this from both sides. You spent three and a half years fighting for her, and now you've got her…"

"I'm not running." Castle insists, unsure why he needs to be defensive.

"I never suggested you were. Just, Katie might be wondering why it is you're so scared about committing with her. And I expect she's just as scared as you are."

"But-"

"She'll fight hard to make it work. She's been yours for longer than you know, Rick. She won't go down without a fight."

Nobody knows it, but he's had a ring for a while. Hidden away in the back of his drawer, a constant reminder of what he told himself he was working towards. Except now he could… now he has the opportunity, he's terrified of taking that step. Except things with Kate are now… awkward. Awkward because they don't talk about it. They carry on like everything is normal, and there isn't this huge thing hanging over their heads. He doesn't sleep, he lies awake wondering just how many more nights he's gonna have with her sleeping next to him. How many morning coffees, how many more crime scenes and arrests and interrogation, how many times is he going to be able to taste her, love her, brand her with his mouth.

She hasn't accepted the job, not as far as he knows, and he could stop her. He could keep her in New York, keep her with him, if only he could just work up the courage. He has no doubt that she'd say yes. He has no doubt that she wants the full deal. This whole mess is because he's too damn terrified of giving it her.

She breaks the news to him over their morning coffee. She's taking the job. She's handing in her resignation, she's ending the lease on her apartment, packing her things up and she's going to Washington. Just like that. Nothing to keep her here anymore. That's what she says, and he feels like he's just been kicked in the gut. He tries to make her see sense, tries to get her to stay, but it seems she's adamant. She's going. And they can pretend that they can make it want all they want, but he knows, in the end, it's going to fall apart. He thinks that it's probably easier to just make a clean break. Let her go. But it's never that easy. He can't give her up.

He doesn't see her for a week. He pretends it because he wants to give her time to pack and prepare, give her space to get used to not having him around, but they both know it's so far from the truth. Distancing himself so when she's hundreds of miles away he can make it out that it doesn't hurt so much. And then it's the day before she's supposed to fly out, and he can't sit around the loft acting like he doesn't care. He sends her a message meet me, and she knows where. He waits for her, sitting and watching the park, the families and the couples and the kids. The teenagers making the most of a pleasant weekend. And then she's walking across the grass towards him, and he doesn't think his chest has felt quite that constricted.

"Hey." He smiles at her, his throat too tight to reply and returns his gaze back to in front of him. He hears her sit on the swing next to him, the creak of the chains as she pushes herself with the toe of her boot. "You've been avoiding me."

"You're leaving." He croaks, and he can't bear to look at her anymore. "Just getting used to not having you around."

"You could come with me. If you didn't have to worry about your family, I would ask you to come with me."

"You're my family too, Kate. You are a part of this family, and you have been for longer than you know."

"Am I?"

"You don't believe me."

She sighs, scuffs the ground with the toe of her boot. "I don't know what you want out of this, Castle. Out of us. Every time I try and talk about it you avoid the question. You're not even subtle about it. But if we're not going anywhere, if we're just going to be stuck in this same old thing, then I don't want that. If that's all we're doing, then I'm drawing a line."

"By moving to Washington. Why Washington, Kate? Why not just… you're happy at the precinct. I thought you were happy."

"Why? Because it's something new. It's something different. I love my job. I do, and I'm proud of what I've managed to do but I didn't want to be a cop. I never wanted this lifestyle, Castle. You know that. The only reason I became a cop is because of my mom, and I've put that behind me. It's over. The FBI is different and it means I don't have to surround myself with death and grieving families every day. It's a new challenge, a new city, new people. I don't want to be a cop my whole life."

"What would convince you to stay?"

She turns her head towards him, and he can almost see the faint pull at the corners of her mouth. A smile. Maybe. "Give me a reason to."

"Kate-"

"You have commitment issues." She interrupts, turning her swing so she can try and face him.

"I don't!" he tries to defend himself, but it's half-hearted and she knows that he knows she's right. "I just…"

"You do. I don't blame you. You've been married twice, you've been divorced twice. I don't want to imagine how many women have tried it on just because of the fame, and you're protective of your daughter. You don't want to be taken for granted, someone to be used just for the money and the fame. I can understand that. And I know that you love me. And I thought that would be enough, and I thought that maybe it would be different. I thought that because you fought for me, you waited for me, it might be different and you wouldn't be so scared of our future."

"I don't think you're taking me for granted. I know you're not in it for the money, and you hate the fame and the parties, you're here because you love me. But what's wrong with what we've got now?"

"There's nothing wrong with this, Castle. What we have now is great. It's wonderful and amazing, and magic. But you're okay just staying like that. We're happy, and there's nothing wrong, and you don't want to make it something more because you're scared that we're just going to fall apart. I said, I told you that I was a one and done type. If I didn't believe so wholeheartedly in us, I wouldn't be here. I wouldn't be having this conversation with you. I'm not asking for a ring on my finger right now, or a house with a garden and a swing, and arguments over what colour we paint the nursery. But I just… I want to know that you want to go there too. That we're heading somewhere."

"I want to go everywhere with you, Kate. I do. I want a house with a garden and a swing, I want you to tell me that you're pregnant with our child, and you're going to laugh whenever you feel him kick. I want school performances and graduation and parties with an overpriced clown, and I want to spoil him rotten. I want your clothes to hang next to mine in the closet, I want your shoe collection to completely overpower mine. I want to trip over your heels every day, every night. I want it all." He stands up, turns and sits on the opposite side of the side so he can face her better.

"You want a boy."

"And a girl. But later. That's – it's…"

"Why can't you let yourself have it, Castle? Why can't you believe that we can make it work? We don't have to rush things. We'll just take it slow. One shoe at a time."

"You don't have an apartment anymore. It'll have to be quicker than one shoe at a time."

"Are you telling me to move in?"

"If it's a good enough reason for you to stay, then yes. I am asking you to move in."

He can't quite believe that he's saying it. He's never really asked anyone to move in with him. Ever. It's always just… happened. One day, they came into his loft and they just didn't leave. It didn't even surprise him. Kate surprises him. Every day. Now, when he finds her stood in front of him, hands on the chains of his swings, looking down at him like he's… everything she hoped for and more. Maybe he is. Maybe he really is her one and done. She slides her hands underneath the lapels of his jacket, up until they reach the back of his neck. He stands and she doesn't waste time in wrapping herself around him. "I'll stay, then."

She wriggles against him, pulls away slightly and he tries to follow because it's been too long since he's seen her and held her and smelt the familiar scent of cherries and vanilla. But she's digging her hand in his jean pocket and his heart is pounding again because he knows what's in that pocket. He knows what she's going to find. She pulls it out, her fingers skimming across the deep purple velvet like it's a tiny, alive thing. Her head is ducked, and he can't see her. He needs to see her.

"I wasn't – I just… I bought it ages ago. Before we even started, and it was something I thought I could work towards. I just had no idea how much the idea scared me." He babbles, just wishing that she'd just lift her head and look at him.

"One day."

"What?"

"One day," she repeats, tucking the box back into his pocket. She doesn't even look, "one day you are going to get down on one knee, or you'll try, anyway, and you're going to ask me. And I'll say yes. But not today, not tomorrow. Whenever you're ready, okay?"

He is ready. Eight months later. They've gone for a late evening walk and a late snow fall has covered the city in a pure white blanket that softens everything. Makes everything even more beautiful. Kate's walking along next to him, mittened hand in his (mittens, she wears mittens), and all he can think about is snowball fights. Girl against boys. Tiny, cold hands in his, hot chocolate afterwards. Piled together on the couch, and slowly, one by one, they'll fall asleep. One of them, him or Kate, will wake up at one point and carry them off to bed. One each, tuck them in before coming back downstairs and collapsing into their own bed. He wants that. He really, really wants that. It catches him unaware, and it makes him completely lose his breath.

"Castle?" He realises that he's stopped in the middle of the path and Kate has jerked to a halt when he stopped her moving. "You okay?"

"Marry me."

"What?"

"Marry me. I – Kate, I want to marry you." He digs around in his coat pocket, looking for the thing that he's taken to carry with him everywhere. Just in case. For instances like this when that pure gut instinct kicks in. Kate's already pulled her mitten off, takes a step sideways so she's standing in front of him. "I can't find it."

"Stop panicking." She puts a hand on his arm, stills his anxious rooting through his pockets. "Inner jacket pocket. That's where it always is."

"Right."

"Breathe, Castle."

"I am. I'm breathing." He digs his hand in the mentioned pocket, lets out a sigh of relief when he feels the familiar velvet. How long has he had this ring now? Two and a half years? He doesn't know. But it fits perfectly on her finger.