A/N: Thank you for the lovely, welcoming response to this story.

I'm alright with a slow burn
Taking my time, let the world turn

- Kacey Musgraves, "Slow Burn"

Slow Burn

Chapter 2

She hasn't gone far. He finds her out in the hallway, holding her hair back as she drinks from the water fountain. He watches how her throat bobs with every sip she swallows and, bizarrely, Castle finds himself swallowing along with her. At least she's not holding her hair back as she vomits in the ladies bathroom, he thinks. Or yelling. She could be yelling.

He approaches slowly, like a zookeeper with a wounded animal, increasing the weight of his footfalls and clearing his throat so that he doesn't startle her. "Beckett?" he says tentatively.

He just proposed to her in the break room. His blood is still buzzing with the hope and excitement he felt when there was a possibility that she might have surprised the hell out of him and said yes (insane, he knows), and now he's reverted to using her surname? Shit! What is wrong with him? What happened to the bravado he felt back there? The rightness of that moment when he dropped to one knee? Like something vampiric, does their relationship wither if it's exposed to too harsh a light?

Kate straightens up, swipes water droplets from her lips with the back of her hand, and whether she heard him walk down the hall or not, it's clear that she knows he's there. She slowly pivots on her high heels to face him, her expression unreadable. She crosses her arms. Her stance is strong and defensive. He fears he's blown everything, has to remind himself that in the past she'd have vanished by now or at least banished him from her precinct. Crossed arms and a defensive posture count as progress with her.

When he drags his gaze up to her face, it isn't with any hope that she's going to respond to his proposal, so he steps over that mess as if it never happened. "What are we doing, Kate?" he asks quietly, sounding sad, almost scared and defeated already.

For once, she bypasses her knee-jerk range of stock responses, which would have included something obtuse like "working a case," or "Go home, Castle. It's late," to acknowledge the look on his face and the intense moment they just shared. "You don't mean work, do you?"

He shakes his head. "Our friends are getting married. Lanie and Espo are⏤"

"No longer together," she fills in for him.

"For now," Castle argues back, a desperate edge creeping into his voice that he knows shouldn't be there, but he just can't stop. "At least they tried…try."

She frowns, and he sees anger and a little spark of fear in her eyes. "Try? You think a relationship is like a pair of shoes? Too bad if they don't fit after a while, you can always get another one? Is that what happened to your marriages, Castle?"

A look of hurt washes over his face the instant these words are out of her mouth, and it persists this time, deepening the creases either side of his mouth, robbing his eyes of their sparkle, of any hope or humor.

Kate closes her eyes and runs a hand through her hair, apologizing immediately. "God, look, I'm sorry. That was crass and hurtful. I didn't mean it. You're a good person, Castle. You just...you blindsided me in there," she says, gesturing weakly towards the break room.

Castle nods to acknowledge her apology and holds up his hands. "I should just keep my mouth shut," he says, beginning to massage his temples. "Ignore me." He starts to back away.

"Weddings do funny things to people. Don't sweat it," she calls after him, willing to play the whole thing off if he is, despite the lump in her throat and the tightness in her chest at the thought of letting it go.

But Castle shakes his head and comes back. "Actually, it's not that. You just…you blindsided me, too, Kate. Before, when you said if we were getting married." His eyebrows shoot up at the memory. "Wow!" he whispers reverently. "Those words…that whole idea…" It just keeps spilling out of him tonight.

He pauses to relive the moment he experienced in the break room a second time, such intense feelings, and Kate watches him, silenced by his candor, by his obvious love and enthusiasm for the concept of them as...husband and wife? These words sound strange and terrifying even inside her head, and she has to look away, to look at anything but his face and the adoration she can see in his eyes, the hope and delight inspired by this fantasy future. It's all too much.

"Kinda hit me in the gut," he admits. "I guess I let my imagination get the better of me. I'm sorry."

Her brow crinkles. Kate feels it and she hates that she's doing that: frowning when he's over there floating in a warm bath of happiness because of a few careless words she uttered just to make a point. But were they really so careless? Or has his bravery started to rub off on her? She certainly wasn't afraid when she said it, either of the idea itself or of sharing it with her partner. She felt playful, conspiratorial; as if she could confide anything in him and he wouldn't judge her for saying it. She trusts him, and it hits her like a lightning bolt just how much.

Tentatively, she finds herself asking, "Do you think about that? Have you thought about⏤" She chews the inside of her cheek. Their eyes are back on one another and it feels as if the hallway might just combust around them. She glances to his left, sees the fire extinguisher mounted on the wall and feels insanely relieved by its presence. God, she's doomed. He's making her as ridiculous as he is.

There's a weighty pause as if Castle's figuring things out before he says, "What if⏤" He holds up a hand in that "hear me out" gesture she's so familiar with from years of his ridiculous theory building. "Okay, let's start simpler. Why aren't you my plus one, Kate? Why aren't we each other's plus one? For the wedding," he adds needlessly.

Simpler than "marry me" but not by much; her heart is thrashing violently.

"Because you're taking Alexis," she fires back, trying to keep the jealous edge out of her voice and pretty much failing. It's his daughter for God's sake, she reminds herself, not some bimbo.

"Only because I bribed her into coming with me," he confesses. "She asked why I wasn't taking you."

Kate's cheeks flood with color at the thought of that conversation. "Oh." She winces, then purses her lips and releases a breath through her nose. Her chest deflates. This discussion is difficult, painfully honest, long overdue, and they should not be having it here.

"Yeah. And when I admitted that I hadn't asked you because I knew you'd turn me down, she took pity on me." There's silence while Castle rubs the back of his neck in discomfort before admitting, "Then she demanded my credit card to go buy herself a new dress."

He chuckles in that self-deprecating way he has when he's poking fun at himself to cover a hurt. Kate hates to see him do that because she knows that he deserves so much more from everyone around him - his mother, his daughter, the boys...her. He deserves her respect, her gratitude, her loyalty, her love, and admiration. Actually, it's more than deserved because he earned it the hard way: by putting himself last so often that it's become the default position in their relationship. His needs, his wants, and desires, she's pretty sure they match hers by now, but because she's not ready, he's forced to mark time in some vague-ass no man's land called Someday.

So she takes a deep breath and goes on the offensive for both their sakes. "How'd you know I'd turn you down? Seems pretty presumptuous," she says, stroking her thumb over the gold shield on her hip to garner courage.

Castle sighs in defeat. "Because I know you, Beckett. We're…friends, I guess. But there are clear boundaries with you. Asking you to be my date to a wedding, Kevin and Jenny's wedding? Come on. Crosses too many lines."

Castle's comments, though true at least in the past, sting. Kate thought they were making excellent progress, she thought he could read her better than that; she sees him as a lot more than just a friend. But then he's not a mindreader, at least not all of the time. And now he's worried about crossing some invisible lines when he found it in himself to propose? It's all so confusing; she has to be the brave one now.

"How would you know if you never asked me?" she demands, facing up to him.

Castle laughs this time, but it sounds flat and forced. "Are you saying you'd have said yes?" He clearly thinks that's an outlandish idea, he's not even hanging on for her answer.

She flips her hair over her shoulder and turns to head back to her desk. "Ask me next time. You never know," she throws back at him.

They both respond to a challenge and she knows that; Castle stands his ground. "What about this time? What if I ask you now?"

Kate raises an eyebrow. "Alexis? A new dress?"

Castle makes a pfff sound and a dismissive gesture. "She's humoring me. She'd jump at the chance to ditch me for this boy she just met."

Kate ambles back towards him, and she's got a sly smile on her lips. "I don't know, Castle. I don't want to come between you and—"

He misses the smile because he's nodding already in anticipation of her rejection. "Say no more. No, I get it. Not a problem." He quickly backs off.

"Check with Alexis," she says as he turns to walk away. "If she's okay with it…" Kate shrugs.

He comes back, his curious expression already turning into a smile. "You'll go with me? Like an actual date?"

Kate's smiling, too, almost laughing at him. His enthusiasm is comical and infectious. She nods. "An actual date," she says softly, her eyes shining. "But get permission first."

Castle laughs in surprise. "We're asking my teenage daughter for permission to go to a wedding as a couple?"

Kate feels her cheeks heat up again. "A couple?"

"Well, no. I just meant…"

She curls her nails into her palms and clenches slightly, needing the pain to fortify her. "Castle, I know what you meant, and it's fine."

He peers at her. "So you're okay with me calling us a couple? For real?"

She hesitates over how to say this. "I—"

He holds up his hands again and starts shaking his head. "Your wall. No. I get it. I'm pushing."

She emits a surprise burst of laughter and slaps her thigh. "Five minutes ago you proposed!" She shakes her head, eyes raised to the ceiling, but she's smiling again. "You proposed to me, Castle! And now you're worried about pushing?" There's a whine in her voice that he's never heard before, it's needy and gorgeous because it's all for him. "Why did you have to propose to me, Rick?" she whines again, some desperate longing on her face like he's put the idea into her head and now she can't get rid of it. Better still, she doesn't even want to.

She growls in frustration, battling sudden tears, her hand pressed against her wildly-beating heart. "Oh, God! We shouldn't even be talking about this here," she hisses as a fresh-faced uniform hurries past the scene of their little melodrama.

Amongst a lot of other things, Castle is struck by her use of his first name; such a rarity. The mixed signals they're trading ping back and forth, thick and fast. "I know. I'm sorry. This is your workplace and⏤"

"Castle, stop agreeing with me!"

He flinches when she snaps at him, and then he looks confused. "I thought that's what you wanted. All these years, I thought you were working to break me in, to get me to agree with you about...stuff."

Kate looks horrified at the prospect. "I don't want a yes man. That's not who you are in this relationship."

She said the R-word, and he's trying so hard not to break into an insane grin or start dancing right in front of her. So he focuses with all his might to ask, "So what am I here for, Kate?"

She does a wild double take as if he's just done something even crazier than ask her to marry him right out of the starting blocks. "You're...you're my partner. Your job is to push me...out of my comfort zone. Particularly when you can see that...that it would be good for me." She eyes him suspiciously. "What? Stop grinning at me like that," she says, starting to laugh herself.

Castle takes a step closer. If he tented his fingers right now they'd brush her sternum. "Like what?" he asks sexily.

"Like that. Like I just said yes to your crazy, crazy question back there."

"I thought we were ignoring that, Beckett?" he says cleverly, making her blush. "But you keep bringing it up. Like maybe you want me to ask you again." He cocks an eyebrow and smirks.

"Castle," she says in admonishment, but he can see that her cheeks are still flushed with heat and her chest is rising and falling faster than usual. Not that he's staring at her chest.

"Yeah, sorry. Your workplace," he says trying to ease her discomfort. He's pushed far enough for one evening.

Kate turns away and then she spins back immediately. "You're not the only one with dreams, you know," she says fiercely.

Castle can only stare at her, slack-jawed shock written all over his face.

"Check with Alexis," she reminds him before disappearing.

TBC...