This story was written for the Winter Hiatus Kink Meme on Livejournal. I'll put the prompt at the end, to avoid too many spoilers.

It was bought on a dare, in college, but it's an impulse that has her putting it on when she gets dressed, that morning. Beckett has no idea where the thought came from, but she decides to run with it. At the very least, it'll be worth it to see his reaction when he finally notices. So, she starts digging through the back of her closet and wondering if it was maybe one of the casualties when her apartment exploded. It takes nearly twenty minutes, but she finally finds it buried in the bottom of box.

A half hour later, she's dressed and out the door. Hitting the speed dial, she calls Castle to let him know she's running late, as she hails a cab. When the driver stops in front of the museum, Castle's waiting outside and hurries over to help her out of the cab and pay the fare. Beckett rolls her eyes and bats his hand away as she pulls the cash out of her purse, then pushes Castle backwards. "I am perfectly capable of paying for my own cab, Castle. Now move, so I can get out."

His need to be chivalrous, opening doors and always paying, is something they will probably never completely agree on. There are days she tolerates it, because she understands it's just his way of caring for the women in his life, and a part of his naturally romantic personality. There are even days it makes her blush and feel cherished and loved. Today is not one of those days. Today, she's enjoying a different sort of confidence than usual, and is in no mood to humor him. Today, she's in the mood to be in control.

The first couple hours progress innocently enough. Beckett honestly expected him to notice within the first few minutes, but he still hasn't. For someone that's made potentially millions of dollars from studying her every move, Castle is being surprisingly oblivious. So, she starts provoking him. Subtly, at first. Running a hand along his back when she passes him. Standing just a bit closer than normal when they're in public. Just doing her best to also be in some sort of physical contact.

It's nearly lunch time when she decides that maybe she's being too subtle. Either Castle is extremely enthralled with the various exhibits, or he's decided to wait her out. Beckett refuses to consider that he's unaffected by her seemingly innocent touches. So, when she drags him away from the dinosaurs, again, and to a diner down the block, she makes him scoot over so she can sit beside him in the booth. Throughout the entire meal, her left hand traces designs up and down his inner thigh. When she doesn't remove her hand even when the waitress notices, he finally decides to comment. "Don't you think you should maybe save the groping for when we aren't in public? Not that I'm not loving all the touching, because I am, but I think you scarred our poor waitress. She looks younger than Alexis." She ignores him, but moves her hand closer to his knee when their waitress comes back.

After their meal, which she paid for before he could dig his wallet out of his back pocket, she heads away from the museum and bites back a smirk when he runs to catch up. They walk in silence, and Castle seems content to follow wherever she leads. Getting an idea, Beckett suddenly stops and hails a cab, ignoring his curious look when she gives an address across town. His increasingly ridiculous guesses finally make her raise an eyebrow and stare until he stops. "You'll find out when we get there, so stop acting like a child. I promise you'll like it." When his eyebrows shoot upwards and he starts coughing when they pull to stop in front of a store advertising fetishwear in bright neon lights, she smirks and gives him a smug glance.

Pushing him out of the cab, she doesn't give him a chance to try to pay before she's headed into the store. They've both hinted at various sex games, over their years of partnership, but they've yet to really explore that part of their sex life. Sure, they've done some basic bondage, with her cuffs and a fuzzy pair he pulled out of his night stand one night. Other than that and a couple role play scenarios, though, their sex life hasn't involved much in the way of toys or games. To be honest, they haven't needed it, but today she's in the mood for something new, and decidedly kinky.

With that in mind, Beckett leads him toward the back, away from the low-end novelty items aimed at the merely curious. When he stops at a rack of crotchless panties, she rolls her eyes and smacks his hand before dragging him away, but makes a note of which item he was reaching for. Stopping in an area devoted to leather and latex clothing, she smirks when his eyes light up and he looks her up and down before turning and flicking though a rack of leather corsets.

More than two hours later she's satisfied with their selections and heads for the cashier. With some help from the clerk, they were able to find thigh high boots, a corset, elbow length fingerless gloves, a garter belt, and a thong, all in black leather. Biting her lip and a pointed look was all it took for him to agree to getting a leather thong for himself. While he was looking over a display of glass dildos, she slipped a few items between the clothing, knowing he would love the chance to try them. When she waves at him to pay for their selections, she doesn't bother to hide her amusement when he almost bounces in excitement. "You know, most men wouldn't be so happy about their girlfriend spending their money."

Grinning at the clerk, he pulls out his credit card, addressing her over his shoulder. "Most men aren't dragged into a sex shop to buy the sexiest leather outfit ever and what looks like bondage supplies and several flavors of lube. You can spend my money this way, any time you want. In fact, I may insist on monthly shopping sprees. No, make that weekly."

The items are all high quality and will last for many years given proper care, so she doesn't waste time feeling guilty, even though they both know the purchase is almost as much as she makes in a week. Knowing Castle revels in any chance to spend money on her, and that he would gladly pay much more to see her in the outfit he helped pick out, eases the last of her doubts. His excitement when the items she'd hidden were rung up and bagged, has her biting her lip and smirking. As soon as they exit the store, he tells her to wait, and runs back in. Ten minutes later, he comes back out, carrying another bag.

Rolling her eyes, Beckett hands him the bags she's holding before wrapping her arms around his neck and pulling him down for a kiss. When his arm goes around her back to pull her closer, she pulls back just enough to watch his face when their hips make contact. The jolt backwards and look of shock and confusion is expected. Him pulling her closer and kissing her hungrily is not, but is more than welcomed. They finally pull apart when a honking horn reminds them they're still standing outside, in front of an adult store, but he doesn't let her pull away. "Katherine Beckett, is that your gun, or are you just happy to see me?"

Pressing her hips further into him, she smirks. "Not my gun, and I am very happy to see you. I was wondering how long it would take you to notice. I was beginning to run out of ways to get your attention."

Another honk, followed by a wolf whistle, has him looking around before dragging her into the mouth of a nearby alley and pushing her against the wall. "You mean, you didn't somehow buy this while I was distracted in the store? You've been wearing this all day? Dirty, dirty girl. I think you need to be punished for not saying something, sooner."

Pushing him backwards, she pushes him against the opposite wall. "Not gonna happen, stud. At least not today. Today, I'm in charge, and I think you should be punished for making me wait all day before you noticed. Do you have any idea how turned on I've been since I put it on? No, you need to be taught to pay more attention to your girlfriend."

His quiet moan when she pushes her hips against him sharply to punctuate her declaration has her stilling in shock for just a moment. Seeing his faint blush and averted eyes, she does it again, and can clearly feel his appreciation for the move. Keeping their hips pressed tightly together, she catches his gaze and speaks quietly, surprised and slightly awed by his reaction. "Rick. I don't... I mean, do you want me to... I've never, but I could, if you want. I just thought it'd shock you, and then we'd laugh about it. I never thought... Wow. Are you ok?"

Closing his eyes, Castle rests his forehead against hers and takes several deep breaths before nodding. Keeping his eyes closed, he pulls her closer and shudders slightly. "I'm ok. I'm fine. That was...unexpected. Not just the...that, but I had no idea I'd like it so much. God, you're the sexiest women I've ever known, so I guess it shouldn't surprise me that even...that turns me on. Why did you...? Where did you even get it? I mean...if you've never...does that mean never, never? Or just, never with a man? I'm not saying I want you to, because I don't know if I do. I just...God, you find new ways to drive me crazy, everyday. This is not a conversation I think I can, or should, have in an alley."

Nodding, she takes a couple steps back and waits while he collects himself. A couple minutes later, they're hailing another cab and heading back to her apartment. The coming conversation requires uninterrupted privacy.

There will be a second chapter coming soon-ish. The prompt will be posted at the end of that. Feel free to make guesses, though.