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

When he wakes up, he immediately senses that something's not right. Kate's not in bed with him. She's not in the bathroom, either–the door's open and the light's not on. Most important, there is no noise in the loft. No not-quite-one-year-old twins, shrieking. No Eliot, bringing in a checker board and demanding a game that he will surely win, though he's not even three years old. No tick-tick-tick of Scrapple's toenails as he chases a ball across the bare floor.

And another thing: he's completely rested. He hasn't felt this way in at least two years. Maybe he's not awake at all. He rolls over and picks up his phone. What? He shakes his head and looks at the screen again. Shakes the phone, checks the screen a third time. Looks at his watch. Apparently it's 11:25. In the morning. A Saturday morning. Also apparently he has come to in someone else's life, or in a parallel universe that happens to look, but not sound, exactly like his.

A few minutes later he walks into the living room and sees his wife at the kitchen counter, reading the Times. She's wearing fuzzy slippers and a long, soft jersey that's slipping down and exposing her very delectable shoulder; even with the fuzzy slippers, and her hand gripping a coffee mug, she's breathtakingly sexy.

"Kate?"

"Castle! Good morning."

" 's almost afternoon."

"Good almost afternoon, then. Sleep well?"

"Like the dead. Which I may be. Where is the rest of our family? Two-legged and four-legged?"

"Alexis took Otis and Abby to her apartment, and Eliot and Scrapple have gone to spend the day and night at their best friend's."

"Perlmutter's?"

"Yup. They were adorable, all bundled up, and Eliot wanting to wheel the little suitcase all by himself."

She looks at him for a few moments before slipping off the stool. When she's a foot away she grabs him by the lapels of his terrycloth bathrobe, pulls him hard against her, and gives him a kiss that could melt the granite countertop and set fire to the newspaper that's lying on top of it.

"Wow," he says, a little unsteadily. "What did I do to deserve that?"

"How would you rate that kiss?" she asks, which is not the answer to his questioin.

"Scorching."

"No, I mean, on a scale."

"Ten. Definitely a ten."

"There's your answer."

"To why I deserved that?"

"Power of ten."

"I don't know what you're talking about. Maybe you should kiss me again. Might clear my head."

She nods, and kisses him–even deeper, and even longer–and this time it's he, not the newspaper or the countertop, that's about to spontaneously combust. His head is anything but clear.

"Need some coffee, Castle?" she purrs. Really, she's purring. And then she nips him very lightly on the ear. "I know just how you like it," she says, running a nail lightly across his cheek before stretching in a decidedly lioness-like way. Not that he's ever seen a lioness stretch, but he can imagine.

"Power of ten?" he wheezes, as he takes a mug from her hand and realizes what he hadn't before, that her jersey is almost see-through. And what he has no trouble seeing through it is her bare breasts. Outline of, anyway. And nipples. "Is this, a, um, special occasion that I don't know about?"

"I told you. Power of ten."

"I was never very good at math."

"Don't have to be. Just good at romance, which you are. I'm counting on it. You have about seven hours to figure it out."

"Maybe I could figure it out better in bed."

"What's wrong with right here?" Her eyes are sparking. Sparking like flint on a rock. He's having very fiery thoughts.

"Well, in bed–" He doesn't finish the sentence because she has taken off her jersey. She's naked. In the kitchen. And they're alone.

"We don't need a bed, do we, Castle? Remember that time during the blackout in July? Four years ago? Against the refrigerator? I slid down when–"

"Yes, yes, I remember that. Vividly."

"Want to try it again?"

"Definitely."

"Then take your clothes off, mister."

"Ooh, bossy."

"You seem to like it."

"Damn right I do."

Which is why, half an hour later, they're lying on the floor eating ice cream, and playing tic-tac-toe on each other's bodies with warm fudge sauce. "This was even better," he says dreamily.

"Last time we didn't have whipped cream."

"True."

"Last time it was boiling hot weather, too, so we didn't want to take a hot shower. But today it's snowing." She feigns a shiver.

"I think I need to get you in the shower."

"I think I need to have you in the shower."

And she did have him in the shower. He's trying, really he is, to understand what the power of ten means in this situation, but this particular situation is taking all his physical power, and he's too enraptured, too ensorcelled by the sight and smell and taste of her, to think numerically. To think at all, really.

Once they're dressed, she grabs a set of keys from the bowl by the door and says, "Don't forget your gloves. We have places to go."

"We do?" He's recovered sufficiently to know that he's speaking in very, very simple sentences. "Where?"

"First stop, the basement. Our storage locker."

Downstairs, stacked neatly right inside the door, are ten cardboard boxes and a large bag. "What's all this?"

"Help me load it in the SUV and I'll tell you."

"Where are we taking it?"

"Not far. But it's heavy, so the car seemed the best bet."

She wasn't kidding. She drives only four blocks before pulling to the curb. He peers through the snow that's already stuck to the window and says, "It's the shelter. Where we got Scrapple."

"Yup. And here comes Jack to help us get the stuff inside. I texted him."

"Hi, Kate," Jack says. "No kids with you today? No Scrapple?"

"Nope. Only the two of us and ten cases of dog food. Five of canned, five of dry. Oh, and a bag of toys. I had the ten dog beds shipped."

"They arrived this morning. We can't thank you enough. Really. You and Rick, it's so nice. And unexpected. Is this a special occasion?"

Just what I asked her earlier, Castle thinks, but he can't answer Jack since he has yet to identify the occasion.

"For us, yeah. Right, Castle?"

"Right. It's our pleasure." Happy as he is to make a donation to the local animal shelter, it's not the same level of pleasure that he recently experienced at home. He hopes they're not radiating sex.

Back in the car he squeezes her thigh. "Power of ten, huh? As in ten boxes and ten dog beds."

"Right you are, Detective Castle," she says, and gives him what he secretly classifies as her Mona Lisa smile, that rare, priceless, mysterious twitch of her lips.

"So, you're not going to tell me?"

"Puh-leeze! No. Not yet. Besides, it's time to watch a movie."

"Fine. I'm in your hands."

"Not while I'm driving, but maybe when we're on the couch."

"I can get a little handsy during this movie?"

"I certainly hope so."

While she's getting the movie, whatever it is, he makes popcorn. When he puts the bowl on the coffee table she has the remote in her hand and is ready to start. "I had to buy this on Amazon," she says, as she wriggles into a comfortable position, her head against his shoulder. "It opened a month before I was born. I can't believe you didn't own it already."

"Then I was eight. Must be an obscure Disney movie."

"Not exactly," she says, and presses play.

He identifies it in the first few seconds of the opening scene, when Dudley Moore backs his Rolls-Royce convertible out of a garage and glances in his rear-view mirror at two young women walking along in bikinis. "It's 10! I saw it five years after it came out. A kid in my class had the video. We played it so often I think we wore it out. A 13-year-old boy's wet dream."

"Did you have the Bo Derek poster?"

"I wished." He slides his arm around her. "But I had no vision of my future. Bo Derek was a ten. You're an eleven."

"Flattery will get you everywhere."

"I hope so. But I'm telling the truth."

"Lemme watch the movie, Castle. I've never seen it."

He's stunned. "Seriously?"

"Seriously. I know, I know. You're shocked. A cultural lacuna."

"God, you're hot. I think you might be a twelve." That nets him another Mona Lisa smile. Two in one day. That's a first. He is a lucky, lucky man, and she does not object when his hand slips inside her shirt.

By the time the movie is over–and as an adult, he appreciates it for its wit and its social commentary, most of which had eluded his 13-year-old self–it's dark. They take a break to phone Alexis and make sure that the twins haven't driven her insane, and to FaceTime with Eliot. He's had a bath and is in his PJs. "Docky make hot dogs for supper!" he reports gleefully. "Not Scrapple. He my hot dog, but not eat him. That my joke!"

"Kind of weird without the kids and Scrap, isn't it?" she says afterwards, a tiny bit wistfully.

"Nice weird, Kate. This has been a great day."

She looks him straight in the eye. "You still haven't a clue, have you?"

"What, about the power of ten? No. Zip."

"Hard to believe, Castle."

"Well, I'll confess something. I haven't been working hard on it. Haven't really chewed it over. You're too distracting, Beckett. I'm just enjoying it. You. Enjoying you."

"Spoken like a true romantic."

"I am a true romantic."

"I know. That's why I'm surprised." Her phone buzzes. "Sorry, wait." She types a quick response to whoever had texted her.

Immediately after, his head jerks backwards. "What's that?"

"What?"

"That noise?"

"I didn't hear anything."

She's fibbing. He knows it. She has a sensational poker face, but they're not playing poker at the moment.

"You didn't hear that clonk on the roof?"

"No. You heard a clonk? Maybe it's Santa."

"It might feel like Christmas with all this snow, but it's almost spring. The Easter Bunny will be here next month."

"Tell you what, Castle, why don't we investigate? Saint Patrick's Day is only a week off, maybe there's a bunch of leprechauns up there, dancing a jig. Let's get our coats."

He grabs his parka and blocks the door. "I'm being set up, aren't I?"

"Could be."

Mona Lisa smile number 3. He can hardly breathe for the joy of it. "I'll let you go out first," he says. "That's what you're always telling me. You're the professional and I'm the civilian."

"I don't think the leprechauns are armed."

"Can't be too sure. Do you have a shelaighlee?"

"No."

"Be careful, then." When he steps onto the roof, he's amazed to see a table set elegantly for two, flanked by a pair of space heaters that give out an impressive amount of warmth. Another table, about 10 feet away, has a hot tray holding a variety of covered dishes.

"Good evening," says a waiter, who is barely visible from his position behind the hot tray.

"Not a leprechaun," Castle whispers as he takes a seat.

"Not unless leprechauns have invaded Italy," she says, unfolding her napkin, putting it on her lap, and reaching for a breadstick. "I'm sorry I couldn't get the actual rooftop, but it's closed for repairs. So I used ours. Never thought there'd be an 'ours'. Not then, anyway." She dips her right hand into her jacket pocket, and holds up her badge. "Detective Kate Beckett, NYPD. Sound familiar?"

His fork, which had just speared an artichoke heart on a plate of antipasti, falls onto the table. "Oh, my God. It's today, isn't it? I'm so embarrassed that I didn't notice. Or think of it."

"Don't be, Castle. But now you know. Power of ten. We met ten years ago today. March ninth, two thousand and nine."

"All these tens, Kate. I love it. And you went to so much trouble."

"Guess I've gotten to be a romantic, too. I can't imagine where I picked that up."

"What made you think of doing all this?"

"I'm sure we'll have a party for our tenth wedding anniversary, but that's a long way off. And there will be a ton of people there. I wanted to do something just for us, with no one else. A tenth anniversary that doesn't mean anything to anyone but us."

They don't talk very much during their superb dinner; when they're not eating they're looking at each other as if they've just met and are astonished at their good luck. After dessert and espresso, they thank the waiter effusively, and go down to the loft. As soon as they've hung up their coats he envelops her in a hug. "Thank you for an incredible day. I've never had anything like it. Never."

"It's not over," she says, tilting her head back to look into his eyes.

"It's not? What's next?"

"You have no idea."

Oh, but he does. He does, and he can't wait. He can't wait.

A/N When Roadrunnerz emailed me this morning and said that Castle premiered ten years ago today, I decided that I couldn't let March 9th go by without writing a little something in honor of the show that we all loved. Castle led me to this world of fanfic and to some wonderful friendships. Thanks to all of you who have read my stories and cheered me on throughout. The show may be gone, but we're still here. So Roadrunnerz, this bit of silliness is for you.