Author's Note: A post-ep for 7x04, 'Child's Play.' Because when I think of princesses apparently I think of pretty dresses, tiaras, Barbies, Star Wars, and ruggedly handsome princes. So I tried to stuff all of that into Castle's backstory.

Playing Princesses

He takes her out to dinner.

Kate's diamond ring sparkles under the dramatic downlighting of the sushi lounge, and even though it's the only piece of jewelry she's wearing, she outshines all of the other celebutantes in the exclusive twenty-seat restaurant.

They actually don't eat at places like this very often, where the bill at the end of the night is well over a thousand dollars and there are photographers waiting outside the door. Usually their hours are so strange that they can't keep reservations at all, so they end up cooking at the loft or ordering out, or on special occasions, hitting up Remy's on the way home. Kate thinks back to all the photos she's seen of Castle on page six over the years and wonders if he ever really enjoyed himself. She's sure his newspaper smiles were nothing like the radiant beam he's wearing now. He's telling her about how he'd fallen on the marbles, how he'd been teased for the wet stain on his pants, and she's giggling - actually giggling - and she wonders how much Sake they've actually gone through.

She's been smiling so widely throughout their meal that her cheeks are sore. She didn't even realize how much she missed being alone with him. Alexis has been out of control. She adores his family - their family - but she loves being with him, just him, being able to tease him with the stroke of a fingernail along his inseam, murmuring sexy little innuendos just to make his brows pop up in mock-surprise.

And it's the only time she gets to wear the dresses. Because Kate Beckett has a secret and he's the only one who knows about it.

She buys dresses. Fancy, frilly, gorgeous things. When Castle had suggested they go undercover at that dance benefit so many years ago, it had been painfully obvious that her wardrobe was lacking sexy dresses. So she'd worn the exquisite burgundy jeweled dress that he sent over, and the next weekend she'd gone shopping.

She owns a lot of dresses now. The blue Herve Leger, the red one-shouldered number, the tight little black one…they're all tied to amazing memories, and she's making another one with him tonight in a teal and gold silk brocade cocktail dress with a sweetheart neckline.

Their conversation has been as varied and delicious as the food. She loves that there are still stories about him that she hasn't heard, loves that he still asks questions about her. She almost can't believe that he's still fascinated by her, that she's still his muse even though she's bared herself to him. It wasn't just the mystery, then.

"So, what toys did you play with as a kid? Did little Katie Beckett have some Barbies?"

"Yes, I had Barbies, Castle. But Ken cheated on my Barbie, so she smacked him so hard his head fell off. He was never really the same after that," she laments.

Castle swallows. "Remind me never to make you mad."

Kate takes a sip of her Sake.

"You were really sweet with Emily."

"Well, she was sweet. Oh, I meant to ask you about that - why did you tell her you play princess with me? I mean, you lied to a little kid, Beckett."

"What are you talking about?"

"She asked if you play princesses with me, and you don't."

She tilts her head down and raises her eyebrows. "Excuse me? I think I most definitely have, at least once," she says.

Uh-oh, he's in trouble. He wracks his brain. Did they play princesses once and he forgot? Surely not…

"Castle? Last Halloween?" she prompts.

OH.

That.

He was thinking of princesses in pink fluffy dresses and conical hats, but yes, actually, she was a princess for him last halloween.

He'll never forget the coppery shine of her skin - so much skin - the metal of the bra digging into her flesh, the long braid that had swayed all the way down her back - the way he grabbed it when he -

Princess Leia. She'd been Princess Leia for him and he'd walked into their bedroom expecting Electra - which had been super hot too - and he'd found her there, in cuffs and chains and that amazing bra and very little else.

He shakes his head to clear the image, because princes don't haul princesses off to the bathroom and ravage them up against the door. Although the bathrooms here are pretty nice, she might not mind… No. Be a gentleman, he reminds himself.

Thankfully, the waiter comes to take their final plates away and Kate leans against him, her head dropping to his shoulder. His fingers rub slow circles on her back.

"This is nice," Castle says.

"Mmm, it is," she agrees. "But we didn't have to do this."

"No, we did. Alexis is in college, she's supposed to be going to keggers and eating cheeseburgers at 3am in hot tubs with her friends, not clinging to me at the loft."

"So we're hiding from her?"

"We're enjoying our engagement," he corrects. "And, I'm treating you like a princess, because I don't do that often enough."

Kate scoffs. "I don't need to be treated like a princess, Castle."

"You don't need to, but relax. You might like it."

"I like it so far - wait a minute." Her head pops up off his shoulder. "There's more, isn't there?"

"I don't know what you're talking about."

She grabs his ear and twists hard. "Castle."

"Ow ow ow! Fine! Apples apples! There's a limo."

"And?"

"And a suite at the Plaza."

"And?"

"Room service. Strawberries and champagne and that thick vanilla cream because you don't like how whipped cream makes you all sticky."

"And?"

"That's all, I swear, I swear!"

Kate releases his ear, but then her expression shifts from interrogatory to coy.

"Well … if we've got dessert at the hotel, what are we waiting for?" she purrs.

The limo is taking way too long to get to The Plaza and the stupid fabric of Kate's dress doesn't stretch at all, so Castle settles for pulling her onto his lap, his other hand searching for the shopping bag on the other seat. He goes in for a distracting kiss while he removes the sparkly, bejeweled object from the tissue paper.

Then he slaps it on her head.

"What the hell, Castle?"

She tries to take the tiara off but the comb is stuck in her hair. She knew she shouldn't have used hairspray. He's laughing like he knows that she'd hate it, cackling, the little runt, and she pokes him to make him stop but he doesn't.

"Castle, if you do not help me get this off my head, I will not have sex with you tonight, so help me - "

He stops laughing immediately and starts untangling it from her hair. The corners of his mouth twitch, and she looks down to hide her own blooming smile. Finally, he works it free. He makes a show of inspecting the cheap plastic gems, then sticks it on his own head.

Kate crosses her arms and glowers at him. "I'm not some damsel in distress, you know."

And then he's smoothing his thumb over the corner of her mouth and looking at her with those sexy, deep blue eyes of his that she can't quite seem to get over.

"I know, Kate. You were never the princess in this story. But even the tough cop with the big gun deserves to be pampered every now and then."

"And this is coming from a man who is wearing a tiara."

"I just wanted you to know, whenever you want to be treated like a princess, just say the word."

She kisses him, hard, because she loves him and he kind of is her Prince Charming.

The limo rolls to a stop and Castle waggles his eyebrows.

"You wanna go play princess with me, Beckett?"

"Yes. But just this once," she says.

His eyes twinkle, because they both know it won't be just once.