Disclaimer: The only part of Castle that I own is the TV on which I watch the show.

Kate wakes up at dawn, curled on her right side, and looks blearily at the phone to check the time. She can just see her Paris airport tee shirt lying on the floor, and smiles at the memory of its removal a few hours ago. But why is she so warm? Much warmer than she should be, given that she's naked and her brand-new air conditioner is humming efficiently in the window.

Someone just licked the back of her thigh, licked a long, wet path that wound up and around to her hip. Someone who's completely hidden under the sheets. Someone with an ass that's now very, very familiar to her, even out of view, even when covered. "Castle! Stop it."

"Stop it?" His voice is slightly muffled, until he pokes his head out and looks at her. "Just the other day in bed you said to me, 'I will never, ever again ask you to hold your tongue'."

"Is this how it's going to be every morning from now on?"

"I certainly hope so. Or is that a complaint? Because you weren't complaining when I did this in Paris."

"Yes, I mean no. Yes. Fuck, Castle, I have to get up and go to work." It takes considerable self-restraint for her to leave the bed and then to keep him at arm's length while they're in the shower, especially since her shower is very small and he is very big.

After they're both dressed and having a cup of coffee she looks with alarm at her left hand. "What am I going to do about my ring?"

"Leave it here," he says, as if the ring were insignificant. As if it were a scarf or a pair of gloves.

"I don't want to leave it here. I don't want to take it off."

He takes her hand and closely examines her finger. "You could put a Band-Aid over it," he suggests.

"It would take an entire box of Band-Aids to cover this. Oh, wait, I have an idea. It's perfect." She walks to the bedroom, with Castle trailing after her, and opens a small box on the top of her dresser. After withdrawing a chain, she unclasps it, removes her ring and slips it on the chain next to her mother's ring. "How's this?" she asks, tucking it inside her blouse.

"Beautiful." He kisses her soundly.

"Let's go," she says, wiping her lipstick off him. "Montgomery always comes in early on Monday and I want to talk to him before anyone else gets in."

When they step out of the elevator at the precinct, half an hour ahead of shift, they find an empty bullpen and their boss in his office. His door is open, and Kate knocks on the frame. "Morning, Captain."

"Morning, Beckett," he says, looking up from his paperwork. "Oh, and Castle. What brings you in at this hour? You don't usually trail in here with coffee for your partner until at least nine o'clock."

"That's sort of what we're here about, sir," she says nervously.

"About coffee?"

"No. Uh, could we talk to you for a moment?"

"Of course. Park yourselves right there on those chairs."

"Thank you." She sits on the edge, and starts running her index finger under the slim gold chain. "Captain, we. Uh, we, Castle and I."

"Spit it out, Detective." He pretends to glower from above his perfectly knotted tie.

"We—we wanted you to know that we're dating."

Castle looks sideways at her. "We're not dating."

"Didn't you two get your story straight before coming to see me? Seems like a pretty simple thing. You're dating or you're not dating, pick one."

Kate is stunned that he sounds neither surprised nor annoyed. "We are, yes. I mean we did." She's trying hard to make sense. "There was no story to get straight, sir. It's worse than that."

"Worse?" Castle squeaks indignantly.

"Not worse, worse. Worse like, it's beyond dating."

Montgomery points his pen at her. "Stop right there. Let me see if I can cut to the chase for you. I've been around a long time, and I think I've got this figured out. You say you're not dating, you're beyond dating. So to me that means one of two things." He holds up two fingers. "You moved in together or you're getting married."

The couple, for perhaps the first time ever, is struck speechless.

"How'm I doing, Beckett? Castle?"

Her recovery time is quicker than his. "It's the latter, sir. We're engaged. Castle proposed to me this weekend and I said yes and here's the ring." She pulls the chain from behind her blouse and holds it up. "And I know it's against departmental rules, but Castle isn't officially a member of the department, I mean he doesn't even have a carry permit or anything even though he's an incredible member of the team and so I guess I'm going out on a limb here sir but shouldn't it be all right for us to date—"

"You're not dating, you're engaged."

"Right, that's right. Well, shouldn't it be okay if we're engaged and then married and shouldn't it make no difference since Castle doesn't get paid for working here so that means he definitely isn't an employee of the NYPD so I think he shouldn't have to stop being here at the precinct when he does such amazing work on our cases, don't you? And I know you like him and think he does a good job, and our closure rate is way up. Please, sir?"

"I have one question, and it's for both of you."

"Okay."

"Okay."

"What took you so damn long?"

They're gobsmacked again.

"What?"

"Huh?"

"Look, you were so busy repressing your feelings—well, Beckett was—that I probably saw this coming before you did. Right from the start. But I can tell you when I was absolutely sure."

"Sure about what?" Beckett says. Castle simply nods.

"That you'd get together. It was inevitable. I may be old enough to be your father, Kate—not yours, Castle, but old enough to be your big brother—but I know chemistry, magnetism, whatever name you want to give it, when I see it. And I knew it as well as I know my kids' names, two months in. Two months after Castle joined us." He looks back and forth between the couple, who are gaping again. "It was the poker games," he says matter-of-factly.

"Poker game?" Beckett looks confused. "There was absolutely nothing going on between us back then."

"Games, plural. And there was something going on between you, even if you couldn't admit it to yourself. We were playing poker at Castle's just before the call came in for that woman who was drowned in motor oil, remember?"

They answer yes in unison, without noticing.

"Castle folded. He had the pot, no question, and threw the game to you, Beckett. And a couple of nights later, when we played again? You did the same thing. You handed the pot to Castle's when it was yours, fair and square. That's love, folks. No question."

"I'll be damned," Castle says.

"So, I apologize for not having said it already, but congratulations, you two. I've been rooting for you from the start." He smiles widely. "You're right, Beckett, the rules don't apply here. You and Castle can continue to work together. Hell, the two of you can get married in the precinct if you want, though I can't imagine why you would. In a couple of years I expect to see both of you walk off the elevator on Bring Your Child to Work Day, with a little Beckett-Castle tagging along." He gets up and walks around the desk to her chair. "You gonna give me a hug, or what?"

She does, so hard that he clutches his ribs after she lets go.

"Strong woman you got there," he says, shaking Castle's hand. "One thing though. You know what I said about being old enough to be your big brother? If you ever, ever give Beckett any grief, I will be the baddest-ass brother you ever saw. Understood?"

"Yes, sir."

"Well, don't you have some work to do?"

"Thank you, Captain," Beckett says. "One more favor? We want to tell the others a little later, so if we could keep this just between us for a while?"

"My lips are closed tighter than a clam dipped in sealing wax. Nobody's gonna hear it from me. Now get out of here, lovebirds."

The lovebirds flutter to the break room. "Oh, my God, can you believe it, Castle?" She's clutching his hand and smiling so hard that her cheeks are pushed up almost to her eyes. "All that worry for nothing."

"You make a persuasive argument." He looks around to make sure that the coast is clear, and gives her a quick but passionate kiss. "Calls for a celebration, don't you think?"

"I do," she says quietly. "But not here. Go get some coffee, but don't come back until your usual time, okay? I'll call if we get a case."

"I guess I can find some way to entertain myself for an hour or two."

"I guess you can," she says, settling in at her desk with a stack of files. But minutes after he leaves she's overcome with a need to talk to Martha. It's much too early to call her Castle's mother, and it's her day off from the theater, but it occurs to Kate that she might even be at the loft. She might have come to the city to see friends or go to a museum or do some shopping. It's hard to believe that so little time has passed since she texted Martha late at night from her sweltering apartment. Everything has changed. Everything. It's magical. She's going to text again, hoping that the result is as good as it was that night.

"Hi, Martha. By any chance are you in NYC today? If so, are you free for dinner? I'd love to see you. Katherine"

It's only after she hits send that she's aware of having signed herself Katherine. Huh, she thinks, Martha's influence. It's almost like a pet name. Families have pet names. Martha's going to be family. Wow.

Ryan arrives not long after and they exchange the usual pleasantries of colleagues and friends. She tells him that she and Castle had a great weekend, adroitly omitting both the location and the main event. Espo is still on vacation and Lanie has taken a few days off to go to her cousin's bachelorette party in Orlando, which takes a lot of pressure off her. She breathes easy, and then the phone rings: there's a body.

Since Castle is only a block away, Beckett and Ryan pick him up on the way to the scene. "Perlmutter," Ryan groans as they slip under the yellow tape, while his two comrades inwardly rejoice. The ME's snideness is infinitely preferable to the gimlet eye of one Dr. Parish.

Unlike their last case, this one is routine, or as routine as a homicide can be: a cuckolded husband exacts revenge on his wife by choking the life out of her. "She didn't deserve to keep breathing, the bitch," he says, by way of explanation. "I had my rights."

"And my rights are to send you out of here with a charge of murder, Mister Kerrigan," Beckett says in disgust, as the 30-year-old as led away. She's only grateful that he has no children. Castle has offered to get lunch for the three of them, and she checks her phone. Martha has replied and yes, she's in town at the loft, and yes, she'd like to have dinner. Beckett sends a reply.

"How about my apartment? At 6? I'm not much of a cook but we could call out if you don't mind that. I can offer you some excellent wine."

"Sounds delightful, and as I'm no gourmet chef either, takeout is just fine. I'm dying to see your nest."

Beckett texts her the address, and when Castle returns with sandwiches she tells him her plan. "I can call for Thai, or Italian."

"You doing paperwork this afternoon?"

"Yeah. And I know you won't be."

"So how about I cook for us? I'll have to buy every single ingredient, because my guess is that you have salt and pepper and that's about it."

"I have soy sauce," she answers primly. "And chicken noodle soup."

"In a can, Beckett." He shudders. "A can. And it's probably dented and past its sell-by date."

When she steps through her door at 5:30, carrying two very pricey bottles of wine and a 99-cent bottle of seltzer, the first thing that hits her is the smell of pasta sauce. The second is the sight of Castle, stirring a pot with a kind of happy concentration. He hasn't heard her. The love in it, the whole domesticity of it, make her eyes fill up. She puts down her bags, pulls off her shoes, and tiptoes into the kitchen. When she presses her forehead between his shoulder blades and wraps her arms around his waist he puts down his spoon. He begins to turn around and she says, "Stay there, Castle. Just stay the way you were." And then she begins to sing, a little wobbly because she's feeling so emotional. Her cheek is resting against his back.

If I could save time in a bottle,
The first thing that I'd like to do
Is to save every day till eternity passes away
Just to spend them with you.

If I could make days last forever,
If words could make wishes come true,
I'd save every day like a treasure and then
Again, I would spend them with you,

When she finishes, he's still and silent for a long time. And then he says, "Me, too, Kate. Me, too."

"I need a Kleenex," she says.

"Makes two of us."

"Your mother's going to be here in less than half an hour. I'm going to change, okay? And I'll set the table."

"Good." When she's halfway across the living room he calls out to her. "Beckett? I love you."

She turns around. "I love you, too." This is a big night, she thinks later, as she brushes her hair. A very big night.

The doorbell rings at exactly 6:00, and Kate opens the door. "Oh, Martha," she says, ushering in her guest and kissing her on the cheek. "Right on time."

"A guest should never be late, darling. Oh, my, what a charming place. I think if I'd been dropped in here and nobody had told me that it was yours, I'd have known. And what is that delicious smell? I thought we were having takeout?"

That's a cue for Castle, who walks out of the bedroom towards the two women. "Surprise!"

Later, when they're catching up and relaxing over wine, Kate says, "Martha, I want to show you something."

"What's that, dear?"

Kate fishes something out of her pocket, hides it in her fist, and passes it to Castle, who puts the ring on her finger. "This," she says, letting the diamond catch the light.

Martha's hands shoot up to her face. "Is that? Did you?"

"We did, Mother. I said, 'Will you marry me?' and she said, 'Yes'."

A few tears, several hugs and kisses, and a brief explanation later, Kate turns to her future mother-in-law. "This never would have happened without you, Martha. I owe you everything. We both do, really."

"Nonsense. You just needed a good strong push."

"And a coconspirator, I hear," Castle says, now able to laugh at the thought of the Beckett-kicks-Gina's-butt moment.

"Well, I will admit that I did my part well," Martha says, fluttering her eyelashes. She turns her head just then and notices that the table is set for four. "Is someone joining us?"

"My dad," Kate says. "I told him last week that Castle—Rick—and I were seeing each other, and he said he wasn't at all surprised. We wanted to have you both here when we told you our news, but since you were the linchpin in this operation, I insisted to Rick that we let you know first."

"I'm honored."

"But I'm counting on you not to reveal anything to my father. I know firsthand how good an actress you are, so, Mrs. Higgins, if you could act surprised when we make our announcement—"

"I'll give a Tony-award winning performance, I promise. It looks like it's going to be the only way I'll get a Tony, so it will give me enormous pleasure. I assume that you've told Alexis?"

"I went down to Princeton several days ago and told her over lunch that I was going to take Kate to Paris and propose, and I wanted her blessing."

"Which she gave you."

"Which she gave us. She nearly drove me insane on Saturday, texting me every ten minutes until I popped the question. We both talked to her on the phone last night when we got back. She's adorably excited."

There's a knock on the door. "On that note," Kate says, "we'll temporarily suspend this conversation. That must be dad."

Dinner goes both smoothly and happily. "You know, Rick," Jim says, after his last mouthful of fusilli with sausage and tomato sauce, "I used to think that you were the rival for my wife's affections. Many a night your face was looking up at me from Johanna's lap. She read your books over and over. Practically swooned over them. And now it looks like my daughter's doing the swooning, which I can assure you is a new thing for her."

"Dad!"

"See? She still doesn't like me saying things like that to her boyfriend, even though she's a grown woman."

"Um, Dad. About that."

"I'm sorry, Katie."

"No, no, don't apologize. It's fine, it's more than fine. But Dad."

"And Mother."

"We have something to tell you."

"I asked Kate to marry me, and she said yes, even though she wasn't suffering from a concussion or any other brain injury."

All four of them jump up from the table to exchange embraces and exclamations. Martha does, indeed, give a Tony-worthy performance. "Thank you," Kate whispers in her ear in the middle of her umpteenth hug of the evening.

"I think this calls for Champagne," Castle announces. "Which I just happen to have put in Kate's fridge this afternoon."

"Probably the only thing in there except maybe sesame noodles from two months ago," Jim says and chuckles. "Now very fuzzy."

"You know your daughter well, Jim."

"I do."

Castle excuses himself to get the Champagne and glasses and Martha says, "You stay with your father, darling, have a moment with him. I'll help my son."

"Katie," Jim says, anxiety putting an edge on his voice.

"Don't worry, Dad," she assures him. "Yours is sparkling cider."

An hour later, with Jim promising to drop Martha off at the loft, they're all at the door. "I'd say that this surprises me, Rick," Jim says, his eyes lighting up, "but since every conversation that I've had with my daughter in the last year has been to some extent about you, I'm not one bit surprised. Just very pleased."

"I'm going to have to ask her about that."

"See how much she'll confess."

"The same is true of Richard, Jim. Katherine can grill him, too. Good night, you two."

"Night, Mother."

"Night, Dad. Don't give away all of my secrets while you're driving Martha home."

"That was good, wasn't it?" Kate says, collapsing against the door after their parents have left.

"It was. And now you're going to tell me what you've been saying about me to your father all this time."

"Not a chance."

"I'll tickle it out of you."

"Not ticklish, Castle."

"Wanna bet?" He traps her against the wall and wiggles his fingers. "You have no idea how talented I am in the tickling department."

"Oh, God."

TBC

A/N Thank you all again. We're heading towards the finish line now.