I am important to her. She comes and goes.
Each morning it is her face that replaces the darkness.
In me she has drowned a young girl, and in me an old woman
Rises toward her day after day, like a terrible fish.
- Mirror, Sylvia Plath

Disclaimer: If I owned Castle, I wouldn't write something so disastrous and broken as that finale.

He's going to leave her. He's going to leave her and the bastard is going to tell her on their damn swings, their one special place outside of his luxurious mattress and thousand thread count sheets.

No, she can't think of him as a bastard. He's been pushed into this. By her. If only she hadn't lied, perhaps she could've persuaded him to come with her- No, he has his mother, his daughter, his life here, she could never do that. And that's okay. Relationships end. As her father had said before, this is the furthest that her relationships ever go. Why on Earth did she expect it to be any different with Castle just because she loves him?

Then he's kneeling on the ground, holding the most beautiful ring she's ever seen, sombre eyes meeting hers as he asks, "Katherine Houghton Beckett, will you marry me?"

Her heart falls out of her chest and her mouth opens, jaw slack.

For a long moment she just sits there, hands curling around the railings of the swings, him on one knee. She knows she ought to say something. She knows she should by the way his sombre eyes turn earnest, his hands beginning to tremble as they hold the ring. Such a beautiful thing. He wants her to wear it on her finger.

But she- she doesn't.

"Kate?" His eyes turn down at the edges as he speaks, voice suddenly tired and regretful compared to the strong way he had proposed.

Her heart flutters in her chest for a moment. Allows herself one tiny second of girlish joy because he's proposed. Proposed. He wants to be her one and done.

Kate reaches out and curls her long fingers around the ring and his hands, stroking his knuckles with her thumb. Fear begins to creep into his eyes. Oh, no, Castle, don't use those puppy dog eyes.

"Castle..." Her voice is trembling, why is it doing that? "It's... This is all very sweet, I suppose. But it's all very wrong."

At her words, Castle falters, slipping onto both knees. His earnest eyes close and she watches the earth-shattering, desolate hopelessness crosses his face. Shadows filling in the lines. She's put those there and it's breaking her heart.

"Wrong." He repeats, slipping his hand from hers.

She watches him as he stares at the ring he cradles in his large palms, as though it were his only back up. His only plan.

"Castle, when you propose to me, I want it to be for the right reasons."

His throat bobs, "When?"

She smiles, slowly, lets it stretch across her face in a way that she hopes is comforting.

"Yeah, Castle, when." She reaches out and cups his neck with her palm, thumb running along his jaw. "I'm not taking the job."

"But..." Castle frowns. "I- You said it was a great opportunity. You- You want more-"

Kate leans down and presses her lips to his, smothering his words and not allowing them to escape his mouth. Oh, how had she let it grow this bad? More. What a stupid word. What a stupid idea. What does 'more' even mean anyway? Does 'more' have to mean that things need to change for the worst?

"More doesn't have to be with a job. I'm just looking to fill the blanks where... We are." She tells him shyly, one hand on his shoulder as she balances awkwardly on the swing.

"We... But I just proposed, what blanks could there-"

"I want it to be for the right reasons, Castle."

"I love you, what other reasons can there be?"

She swallows roughly, tears glittering her eyes just because of those three words. How silly. At a time like this, she's just- Silly. It's ridiculous.

"You're using it as a way to get me to stay."

"No, no, I wasn't-"

"I know you said you'd stick by me and you haven't given me an ultimatum, which I'm grateful for. But you're just... You want us to have a reason to be together if I took the job. You want us to have a reason not to let go of each other. And that's not... When you propose, Castle, I want it to be because you love me and because you want to be my one and done." She finishes, taking a deep breath and slipping from the swing, kneeling before him. She cups his face in her palms and forces his drifting eyes and heart to focus on her. "We're gonna get married one day, okay? We're gonna have more. Us, Castle. I know we don't talk about it. And I think it's time we should."

Kate reaches down and curls Castle's hands around the ring, pressing another light kiss to his lips.

"Keep it. For... For one day."

Castle takes one deep breath, than another, and she lets him have his moment. With her hands curled around his, comforting. There. He's been there for her, maybe she ought to do the same.

Castle's brows knit together and he turns his timid blue eyes back up to hers. "Why? Why are you... Why are you gonna stay? Because, Beckett, if it's because of me-"

"It's not. It's not all because of you. It's..." She struggles with how to put her thoughts into words, take a moment to think carefully about his words so that he doesn't misinterpret her once again.

"I don't wanna become a suit. I wanna be human. I saw how they all were in DC, dressed up so fancy, keeping emotions at bay. And maybe once I would've wanted that, but that's not what I want now. I want to stay here. Where my home is. I don't need that job, Castle. I don't need to be that cynical. But I need you. I want more, sure, but I want more with you. I want marriage and to live with you and kids and everything else that comes with it."

He goes quiet, and for a moment she said she's said too much. Sure, he proposed, but he's been married twice- Perhaps it's not a big deal to him as it is to her. Maybe she's scared him off. They've never discussed marriage or living together, let alone kids- Does he even want more? Does he want more with her?

"Whatever you decide to do... I'm with you." He says, voice like gravel.

She places a finger beneath his chin, tips his face up to meet hers. "I love you. We'll have this someday. You understand?"

A grin tugs at the corner of his lips. She feels exhilaration seeping through her veins; that twinkle in his eyes, there's the man that she fell in love with.

"Yeah. Okay."

Kate stands, reaching a hand out to him. He takes it easily, standing to his feet too as he slips the ring inside his blazer pocket.

"Where are we going?"

She almost laughs at his question, instead lets her grin spring free. "Home. To have really, really hot celebratory sex."

Castle chokes on his words. "What are we celebrating?"

Kate leans in, fists her hands in his blazer as she kisses him fiercely.

"Us."

It escapes her eight months later.

They're investigating the murder of a young child and it takes its toll on the both of them. Yet, when they finish the case and catch the bastard, and Gates tells them to go home, Castle has enough energy to practically carry her from their front door to their bed, lays her out and tugs her boots off. She watches him in admiration as he tucks the sheets around her and slips in beside her, one arm wrapping around her stomach. Breathes him in, that smell of spice and wonder and words.

He is so good to her. And this is the furthest she's ever reached in a relationship. She isn't going anywhere.

"Marry me."

Her words are strong and crystal clear and in the darkness of their bedroom at one am, all she can see is his crystal blue eyes.

"What?

"Marry me, Castle. Be my one and done."

Castle's hand around hers is still, chest rising rapidly as his breathing grows erratic. She presses her palm against his chest, feels his heart beat beneath his skin and the soft cotton of his t-shirt.

"You still have the ring, right?" As he nods, she nudges him. "Then put it on my finger already."

Castle rolls over quickly, finding the velvet box in his drawer. Opens it and once again she is absorbed by how stunning the ring is, the way it twinkles like his eyes when she says I love you.

Slowly, Castle pushes the ring onto her finger, and it's a perfect fit. It makes her grin so much that their teeth knock together when she attempts to kiss him. Makes her laugh.

"I see what you meant now."

She raises an eyebrow at him. "What I meant?"

"It was for the wrong reasons. This is- This is just us. Being together."

"Yeah." She whispers, slipping her legs between his and resting her head on his chest. "Yeah, it is."

"I love you."

A smile blooms across her face again and she hides her face in his top. "I love you too." She mumbles, still feeling a thrill run through her at the words.

His voice is sleepy when he speaks, hands sweeping up her spine. "Can we save the celebratory sex until tomorrow? I don't think I'd be quite up to par tonight."

She laughs, but soon it morphs into a yawn. "Well, I suppose I can live with that." She says as her eyes flutter shut and she begins to feel sleep overwhelming her.

She's not quite sure if it's real or in her dreams when he whispers into her hair, "One and done, Kate. One and done."