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

It all begins with cereal.

It's the day after the case involving the smuggling of endangered species. The one in which Kate Beckett and Rick Castle had been left handcuffed together in a filthy basement with a very hungry, very large tiger who had made it clear that they were her next meal, à la carte. They had gotten off the menu in the nick of time.

At 9:30 a.m. Castle steps out of the elevator and saunters to Beckett's desk. "Good morning, Detective," he says, placing a large cup of coffee and a brown-paper grocery bag in front of her.

"Thanks, Castle," she says, raising the latte in salute. She nods her head at his other offering. "What's that?"

"Open it and see." He looks very pleased with himself.

She, on the other hand, looks highly suspicious as she pulls the bag towards her, unrolls the top, and peers inside. "You got me Frosted Flakes?"

"I did. I thought you might be hungry, Beckett. And I thought you could use a little sweetness after the difficult day we had."

"At least it's not beef jerky."

"Hey, the tiger liked it. I probably saved our lives with that."

"Right. You know, I haven't had Frosted Flakes since I was in fourth grade."

"Then you're long overdue. Dig in."

"Well, for that I'd need a bowl and a spoon and milk."

"Which I am more than happy to provide," he says, producing another bag from behind his back before taking off his coat and sitting down. "I took the liberty of bringing two of everything. Hope you don't mind if I join you." He puts bowls, spoons, and half-pint cartons of milk on the edge of the desk, opens the box of cereal, and pours out two servings of sugar-coated cornflakes. He waits for her to begin; as soon she does, he takes a large bite and swallows noisily. "Mmm, these are …..These are…." He looks expectantly at her. She looks back, and slowly licks a tiny drop of milk from her bottom lip. He tries not to swoon girlishly. "Beckett? These are…."

She can't resist. She'll do it. She leans across her keyboard until she's only inches away from him. "Grrrrrrreat!" Then she bounces back in her chair and laughs. "Thanks, Tony." She has another spoonful.

"You're welcome." He's a happy man.

Castle stays for a few hours, fills in a couple of details on the case for which Beckett is doing the paperwork, and hangs out a bit with Ryan and Esposito. By noon he's ready to leave.

"Sorry you can't find anything to captivate you here, Castle," Beckett says, watching him put on his scarf.

"We'll call you when there's some fresh meat," Ryan adds, accepting a fist bump from his partner.

"Thanks. Well, I have an important errand to do. See you, guys."

Riding down in the elevator, Castle mulls over what Beckett had said to him at the precinct the previous day, right after they had closed the case. He hadn't imagined it. She'd said, "For what it's worth, if I ever have to spend another night handcuffed to someone again, I wouldn't mind if it was you." He had played that sentence over and over and over again in his brain, all evening. Turned it upside down and inside out. He couldn't sleep for it, and had finally gotten out of bed, gone to his office, and begun to sketch out a plan. This is it: he's not waiting any longer for Kate Beckett. He's going to woo her, not with flowers and candy, because that's not her style. She's extraordinary, and he's going to win her over in out-of-the-ordinary ways. Frosted Flakes was just the beginning, a way to sweeten her up a little. Cereal was part one. His important errand is part two: he's off to a place he knows on West 44th, where the owner promises that he has exactly what he needs. So what if it sets him back 850 bucks? Besides, the cereal was only four ninety-nine.

While Castle's in a specialty shop in midtown, Beckett takes a quick look around the bullpen. The boys have stepped out; she's in no one's sight line. She furtively opens her bottom drawer, pushes her hand inside, and comes up with a fistful of Frosted Flakes, which she downs in an instant. "Even better without milk," she says to herself, smiling in a brief and silent acknowledgement that Castle is, God help her, adorable.

There's no new case the following day, so she's surprised when she sees her partner crossing the floor. "Hey, Castle. What's up?"

"Not much. I was in the neighborhood so I thought I'd drop by. It's brutal out there."

"Brutal? Doesn't seem that cold. Isn't it 35 degrees, something like that?"

"I meant the Christmas shoppers, slamming you in the kidneys with their bags of presents. All those people who wait 'til the last minute. They should totally have finished by now."

"It's December ninth, Castle. Christmas is still two weeks away. Not exactly last-minute."

"Sixteen days away, and I was done before Thanksgiving."

"Not everyone is as obsessive as you about the holidays. And if you were finished last month, why did you have to dash off shopping yesterday when you could have stayed here and actually helped?"

"I didn't say I was shopping, I said I was going on an important errand."

Just as he plops down in his chair, she stands up. "In my experience? For you those two words, shopping and errand, are interchangeable. But since you're here, escaping the bedlam that you claim is just outside our doors, do you want coffee? I'm getting some."

"Thanks, yes."

When she comes back from the break room carrying two mugs she spies a small envelope leaning against her phone. "Castle?"

"Hmm?"

"You put this here?"

"Yup."

"It's from the baseball place. The one with all those amazing collectibles."

"Yup."

"Who are you all of a sudden, Calvin Coolidge?"

"Nope."

"Drink your coffee, Cal. I'm going to open this." She has just put a fingertip under the sealed flap when she stops and looks at him. "This wouldn't be what your errand was about, would it?"

"Yup."

"Oh my God, I'm going to rip this open and—"

He looks alarmed, and reaches out to stop her. "No, Beckett, be careful! Don't tear it."

She laughs. "You're so easy, Castle. You know I never open anything that way. You're the one who's unwraps things like a six-year-old." She carefully opens the envelope and slips out a small plastic sleeve that's protecting a small piece of cardboard.

Watching her face as she realizes what she's holding is melting him, and he has to call on priestly self-control to prevent himself from jumping across the desk and kissing her as hard as he can.

"Castle?"

Oh, dear God, the way she said that. The drawing out of the s. The little uptick at the end. The elllllll. He could die right now.

"This is, this is—"

"Tiger got your tongue, Beckett?"

"Al Kaline. This is Al Kaline's rookie card."

"It is. And Al Kaline, a.k.a. Mister Tiger, signed it personally. I'm told he played for the Detroit Tigers for twenty-two years."

"He did. But Castle, this must have cost a fortune. I can't accept this."

"I can afford it. The Nikki Heat books alone have made me—well, never mind how much they've made me. Should be giving you half the royalties, except you've already refused to accept them. So accept this."

"But—"

"I know you don't really celebrate Christmas or it could be your Christmas present. Let's call it a commemoration of our having narrowly escaped death at the hands—well, paws—of a tiger. I'd have gotten you a card of a Yankee legend like Babe Ruth, but under the circumstances one of a Detroit Tiger seemed more appropriate."

Her eyes are still wide, and still gleaming. "But how did you even know that I'm an Al Kaline fan?"

"You might have demonstrated to me your interest in baseball on a few occasions. Like about fifty. "

"Oh, please, I have not."

"How about that interminable stake out last April when you insisted on reciting every Yankee lineup from 1987 to the present? And describing to me in excruciating detail the Hall of Fame players you most admire."

Does she know her face is coloring? Because it is. She's blushing. Actually blushing. Right here in front of him.

"You told me that was hot."

Her face is redder now.

"What I thought was hot was the way you said two of the Hall of Fame guys. Cristóbal Torriente and Al Kaline."

"You remember me saying Cristóbal Torriente and Al Kaline?"

"Just because I sometimes ignore what you say doesn't mean I'm not listening. I remember everything you say, especially if it sounds sexy."

"Geez, Castle, you think Al Kaline's name sounds sexy?"

"When you say it? Yeah, Kaline. It sounds feral, feline." He takes a chance and looks her right in the eye. "Like a wildcat."

She sits up very straight, and arranges her face into a passive expression. "I thought you'd had enough of wildcats."

"Not human ones, Kate." He lands hard on the K.

Beckett tucks a strand of hair behind her hair, which he knows is a tell: she's embarrassed, but pleased. Ah, he's got her. Okay, not got her yet, but he's made a little progress. Now she's clearing her throat, another tell. "Well, anyway, thank you. This card—it's incredible. I'm going to take it home, can't leave it here. I'll treasure this, really."

He's got his chin in his palm, and he's still looking at her. "Got your own personal hall of fame at home, do you?"

"I might."

See! See! There it is! The all-but-invisible-except-to-him movement at the corner of her mouth when she's suppressing a smile. "Am I going to get to see it? You know, now that I've contributed something."

"Maybe." She tidies up the already perfectly aligned pencils that are next to her pile of manila folders. "I gotta finish this up," she says, patting the folder on top. "I don't suppose you'd like to assist for once?"

"Nope. Going to brave the madness outside again. Got to go to the supermarket, cupboards are practically bare."

"Down to your last case of gourmet popcorn, are you?" Now she really is smiling.

"Something like that. Tomorrow, Detective?"

"I'll be here, Castle." She puts her palm over the baseball card. "Seriously, thanks again. For this."

"My pleasure," he says as he turns to go to the elevator. His expression says it, too.

Her shift ends several hours later. She hasn't been out all day, not once, and she's looking forward to the fresh air. She pulls open the desk drawer where she keeps her bag and finds a manila envelope on top, addressed to her. Huh. It's from Comicadia, the best comic-book store in the city—no, best one in the country. She and Castle had even been there together on a case a couple of months ago. Could it—? No. Yes. No. He must have put it in there this morning when she was in the break room, getting coffee. She wants to open it at home, but over the years some of Castle's exuberance has worn off on her, and she doesn't want to wait to look. It's a copy of issue number 5 of Watchmen, from about 25 years ago. Huh. She lets her mind wander. Aha! Got it. It's the "Fearful Symmetry" chapter and she's pretty sure… wait, wait, she flips to the end and smacks the page. Yes! There it is, a quote from Blake's poem. "Tyger, Tyger/burning bright." She's glad that he's not there to hear her chuckle.

She gets her phone and calls Castle, who answers on the first ring.

"Beckett?"

"Very clever."

"I love being called clever, but what's the occasion?"

"The comic book."

"Oh, you found it!"

"Pretty hard to miss. Although I should be ticked off at you for going through my drawers."

"I'd love to go through your drawers, but I did no such thing. I opened one drawer, singular, of your desk, which is technically police property and thus not yours, and left an envelope on top of your bag. Into which I did not look. Your bag."

"Overlooking the legal niceties, and possible trespass, thank you for the comic. 'Tyger, tyger.' I see a theme here, a very tigerish theme."

"That's why you're the best detective in the NYPD, Beckett. Nothing gets by you."

"So, Castle, is there a reason for this tiger—this, uh, tiger largesse?"

He's quiet for a moment, wants to put this the right way.

"Castle?"

"Hi. Here. Well, that was a hell of a time we had with the tiger and I thought it would be nice to give you something—for you to have something good to remember about it."

Now it's her turn to be quiet. "I already do."

She said that? She really said that? "Me, too."

"Night, Castle."

"Tomorrow, Beckett." He puts down his phone, an even happier man now than he was yesterday.

TBC

A/N From a one-word prompt from mobazan27: Pertinacity

A/N To those who live in places where Frosted Flakes are not part of the cultural fabric: the cereal's spokes-animal is Tony the Tiger, who calls the cornflakes grrrrrreat!