1: External architecture

He's always thought that he'd love her underwear. Speculated about it right from moment one, (what do hot cops wear under their clothes, he'd thought, and hoped she'd show him.) though he hadn't managed to spot any of it when she was leaning over with her palms flat and face furious, across an interrogation table. He thought he'd struck lucky (he'd even bought a lottery ticket that day) when she popped an extra button and showed an edge of scarlet lace at the top of the stairs to a then-dingy bar, a year after. His luck hadn't held for more than five minutes, but he'd nearly swallowed his tongue. And then he'd nearly swallowed hers, and only the way she'd chambered a round and a faint remaining trace of self-preservation had stopped him. A year later, it had still figured in his dreams: the blazing contrast between scarlet lace and cream skin. Then he'd kissed her and everything had changed.

Until he'd met her, he'd never really considered the infinite possibilities and subtle modulations of women's underwear. Sure, he'd appreciated it – frequently as a frame for his signature, in his hellion days as celebrity Casanova Castle, still, then, not long behind him; or as an attractive wrapping, but still a wrapping, to be removed and discarded so that he could play with the gift which had presented itself to him.

Until he'd met her, he'd never properly appreciated lingerie at all. He learned to discern her mood from tiny differences in her silhouette – he hopes she doesn't know it – under the t-shirt or button-down or soft clinging sweater: on the days when she started angry or on edge or upset it was a little less precise, a little less moulded, as if her underwear were softer to make up for her hard temper, or as if she didn't care enough to choose that day. On other days, days when her smile took on a flirtatious edge, she was more confident, and her profile formed to attract the eye. His eye.

Now, he can tell her mood and the likely pattern of the day before he's really awake, and her entire lingerie collection – and it is truly extensive: Kate Beckett is the Imelda Marcos of stunning lingerie – is residing, with its owner, in his loft. Permanently.

Most days, he can tell her mood from her underwear: soft plain cotton on the thankfully rare occasions when she's in some pain or discomfort (when the scar is hurting, he thinks privately, because he knows that sometimes, even now, it still does: mentally or physically); lustrous silk when she's planning to tease him all day; balconette bras when she's dressing to intimidate other women because then she feels absolutely powerful in her own female – not feminine - skin; whatever the hell she likes when she's planning to intimidate men because she doesn't need anything at all to help her do that; and sometimes some very special underwear sets when she wants to reduce him to drooling sludge in the shape of a man. Sometimes she lets him choose, and then as he dresses her in it he tells her all the ways he'll take it off her, and what he'll do with her and to her and for her as he does. They leave work on time, those days. Oh yes.

But right now he's pouting. It's not a sulk, because he never sulks. But there is a definite pout. Beckett got dressed before he was even awake, and in the bathroom with the door shut to boot. Which is just not on. He may not like early, but he likes missing out on the sight of nearly-nude (or preferably totally nude) Beckett even less. She's deprived him of his morning treat. One of them. And since she's already left – which is not fair – there is no chance of other morning treats for either of them that are not coffee and bear claws. Humph.

He makes himself pancakes for breakfast to cheer himself up, eats them in solitary splendour, showers, dresses and, still pouting, makes his way to the precinct. They will have words about this business of dressing when he isn't watching, later on. She'll be sorry. In the most enjoyable possible way, she will be sorry. He'll forgive her, of course. After he's given her what she deserves. Mmmmm.

He wends his way to the bullpen, where Beckett is dressed extremely conservatively in dress pants and smooth button-down, and is deep in the day's work, head down.

But then she hears his step – this is what happens between them now, she recognises his walk no matter how he tries to disguise it, even when she isn't listening at all and is deep in concentration – and looks up and smiles with that edge of smirk that always means I know something you don't know. He does it too, some days. When he smiles back and she adds an edge of sexuality and seduction he has the feeling she might have bought something new. As he slowly looks her up and down and her smile becomes ever more scorchingly seductive he's sure of it. Today is going to be exquisitely anticipatory, for both of them. He smiles with the predatory edge of an alpha wolf and starts to play the game.

There's a definite structural variation to her silhouette, he realises over the course of the exceedingly uncomfortable day. He can't quite put a finger on it – he can't put a finger on her, because it's the precinct and she will shoot him – but there is a difference. When they go to get lunch he tries to investigate but she takes his hand in hers so he can't even put an arm round her.

"Beckett, what are you wearing today?"

"A coat."

"Beckett," he whines, disguising his desire not at all. She smirks, and twines her fingers tighter through his.

"A blue button-down and navy dress pants," she says cheerfully.

"What else?" he says hopefully, and widens his eyes to his very best big blue puppy-dog plaintive look.

"Underwear." It hasn't worked. He tries the look again. Beckett chucks him under the chin as if he's five. "Poor baby," she says very insincerely. Then she grins evilly. "Or maybe nothing." He stumbles. It's the uneven sidewalk, not the sudden vision of Beckett bare under her shirt and pants. Really. She even evades his attempt to kiss her. Oh, she is going to pay for this.

"It's not fair," he mutters darkly.

"What's not fair?"

"You've bought something new and you haven't told me."

"Really? How would I do that without you noticing? Especially with your famous powers of observation."

"I don't know. But you have."

Beckett raises an eyebrow and eats her lunch. Smugly. She is going to suffer for this. She'll beg him for relief. Oh, she will beg. And she knows it.

"I wanna know what's under the shirt," he grumps.

"I want doesn't get," Beckett says smartly, and dodges his grab for her by dancing into the elevator. She's smirking, again.

She smirks all afternoon. Every time Castle tries smooth persuasion, she smirks and evades. Every time he tries pleading puppy-dog eyes, she smirks and pats his cheek. Every time he growls darkly into her ear when they're alone in the break room, she smirks and whispers truly filthy suggestions for later into his ear. And every time they're alone, she makes sure that she's holding his hands. By the end of the day, he is wound up to boiling point and pulling her into a windowless room, locking the door and showing her why teasing him all day is a really bad – or really good – idea hasn't left his mind for more than ten seconds at a time for the last hour.

"Catch," she says, and tosses him the car keys, which he automatically catches.

"W-what?"

"Go get the car, Castle. You can drive. I'll just tidy up before I leave." He? He gets to drive? He never gets to drive her car. He bounces out the bullpen and is already turning the key in the ignition when he stops. That sneaky, conniving, witch.

Said sneaky, conniving witch appears in the passenger seat. Smirking.

"You…you…you… You did this deliberately!"

"Did what? You always want to drive, and today I thought" – she licks her lips, slowly – "you deserved a treat." She follows up by nibbling on her lip. "Let's go home, Castle."

"You deliberately let me think I'd get to drive."

"You are driving," Beckett points out, innocently.

"And if I'm driving I have to keep both hands on the wheel or you'll arrest me."

"Yep," Beckett says, happily.

"I wanna know what you're wearing," he pouts.

"Yep," Beckett says again, even more happily.

"And if I've got both hands on the wheel I can't touch you," he whines.

"Yep," Beckett says for a third time, delighted by her own cleverness.

"When we get home you are going to regret this, Beckett," Castle growls deeply. "You think I can't tease you until you beg me to stop?"

"Funny," she replies airily, "I thought you were just about at the point of begging me to start."

He flicks a glance at her, which has changed in the last few minutes from plaintive boyishness to his best wait till I get you home look. Beckett wriggles. She surely knows what that look means by now. Her eyes have begun to darken already. Out the corner of his eye he spots her opening one button. Only one. Just enough to show the very start of her cleavage. Not enough to show him whatever it is she's bought. Well, he'll find out soon enough.

He doesn't chase her to the elevator. That would be undignified. He merely walks. The working day is done, and now they can start the game properly. Beckett's had her turn, and now it's his. She has, he knows, known exactly what she's doing and what she's inviting him to do all day. Well, he's got some thoughts on that. A few… refinements… to their usual play. They had, after all, promised never to be boring.

The loft is empty. Beckett clearly knew that it would be, or arranged for it to be. Castle had expected that, too, right from her first sensual smile when he walked into the bullpen. A planned seduction is very… satisfying. He loves it when she plans their evenings: she isn't good at words, but her actions show him everything she doesn't say.

And then the door clicks shut and he can stop focusing on anything other than Beckett. He reaches for her, fast as a cobra striking, catches her against him, still in her coat.

"Tease," he rasps. "Well, now it's my turn." He runs one firm hand into her hair and tips her head to the correct angle to invade and conquer her mouth: sure, hard, a little rough and a lot demanding, wholly possessive. She's instantly responsive under the kiss. He continues kissing, deep and devouring, till she's softened against him, till the teasing smirk is wholly gone and all that's left is sheer desire and the mutual understanding that he'll set the plays tonight. If he'd wound her up all day, then she would. But this evening is his.

More kisses, so she's making sexy little noises and pushing against him: perfectly, beautifully receptive: the soft to his hard. They fit so well: they fill each other's voids and spaces: his stability and her ferocity; his imagination and her logic. Together, they're not just more, they're everything.

Finally, he lifts; leaving her dark-eyed, dazed and flushed; breathing harder. He smiles, dark and feral.

"My turn," he murmurs again, sexuality slinking through his voice. "I'm going to stay in here. You're going to go into our bedroom, strip down to your pretty new underwear and heels and come back out here – like you've been planning all day."

Her eyes widen. She's often given him a show, but only in the bedroom.

"You want a show?" she husks, dripping suggestion from each word, not yet moving, coat still on. "I can give you a show right here." She raises her hands to the fastenings of her coat.

"No. Do as I" – he nearly says ask, but he recognises her mood – "told you. I want you to model for me."

Beckett runs the very tip of her tongue over her lips so that they part and glisten damply, and then turns smoothly with the grace of a catwalk queen. Castle removes his own coat and jacket and lounges on the couch to wait.

He's ready for nearly anything when the study door starts to open. Anything, in fact.

Anything except what he sees.

Ohfuckohfuckohfuck. That is a structural variation on sin and sex that he'd never imagined on Beckett. That turns Beckett's already glorious body into sexuality's equivalent of Michelangelo's David: utter perfection.

Some seconds later he remembers to close his mouth.

And then she moves, and all thought and function is wholly lost. She prowls like a leopard and flows like the sea: as smooth and powerful and dangerous as either. He drowned long since, without a struggle. He can only stare.

It's cream. She never wears cream: pure white or bold colours to stand out against her skin; stark black or emerald green; deep blue or blood-crimson. This is cream. For a moment, that's all he registers.

No wonder she'd worn a button-down and tailored, slightly loose dress pants. Anything else, he'd have spotted the differences in an instant – and Interrogation One would have been put to a use which is strictly not permitted. He doesn't even recognise the noise coming from his throat. It's not exactly a growl, or a groan. It's some primitive noise of ownership and lust and fuck she's mine.

"Stop," he orders. She's close enough for him to see the detail and not close enough to pounce. It's a – his modernity keeps trying to say basque, but his brain is saying corset – corset. She is wearing a very modern version of an old-fashioned silk corset, with stockings which are surely also silk and a very minimal pair of cream silk panties. And black stilettos. She's a wet dream walking, a weapon of mass destruction. No heterosexual male would resist her commands.

A cream silk corset. Delicate bows at the front, less than demi-cup bra, pushing up her breasts and laying them out, only just covered, perfectly presented for whatever he might lavish on them. Her waist tiny, emphasised far more than usual, the fabric flaring out over her hips. It's the very epitome of an hourglass figure. Four slim garter straps, attached to the stockings.

"Turn around," he rasps. His voice isn't working very well.

His voice stops working at all.

It laces up the back. There is no gap at all. She is poured into it as if she were molten gold into a form. Some small fragment of instinctual brain prods him till he notices that her breathing is very slightly shallower than usual. He knows that sometimes she likes to be restricted. Since they came in, then, she's tightened those laces, because she would never have had pulled them as tight as that at work. She's tied up, without being tied up. This is so far past arousing it's indescribable.

It takes him four tries to force out words. "Come here." She does, with a slinky, sensual sashay that leaves him barely in control of his body. His body is screaming take her. His brain is almost dead. One last tiny flicker of life in it says reduce her to a puddle of sensation. He makes a monumental effort and recovers a shred of suavity; waits till she's arrived by him, and then looks her up and down again, very slowly, all the heat and desire and lust and love that he feels on full display. She flicks a fast glance down over him, certainly not missing the visible evidence of his arousal bulging against his pants, and acquires the satisfied smile of the cat who's face-down in the cream.

"Like what you see?" she purrs.

"So much. You dressed up, all for me." He reaches out and runs his hands lightly over her sides, not holding her. She wriggles a little. "You're all wet, just for me. Dressed like that, I can see just how excited you are." His face is hot and intent, now. "You're framed, like a picture." His hands slide over her again, a little more firmly, pulling her closer. He leans in and swiftly flicks his tongue over the upper curve of her breast, and she squirms in his grip. "Bound in. It's just a little tight, isn't it? Just a little constraining? The panties are a darker shade of cream, now. "Like when I hold you close, don't let you out my arms, stop you taking charge…"

He's grasping her firmly, now, one arm locked around her, still pulling her forward. The other hand slides between her legs. "Definitely all wet." He slides the soft fabric a little side-to-side, listens to the gasp, the different sound of her breathing with the slight tightness of the corset around her ribs and waist. "I don't think you need these any more," he decides, and removes them.

"You're overdressed, Castle," Beckett tries. He's pretty sure what she wants. Him. Now. Well, she's made him wait, all hot and bothered, so it seems only fair to return the favour.

"You've teased all day. It's my turn," he replies reasonably, and lets his fingers slide through slick heat. She emits a little gasp that's tending to a mewl, which turns to an outright moan when he puts his mouth back on her breast and starts to turn her on. His mobile lips tug gently, and when that's left her nipples hard and her flesh a little coloured and swollen he sucks harder and nips and grips her waist, narrower than he's used to, to stop her falling into him just right now. They'll get to that, later. Right now, he's going to turn her to liquid under his hands and mouth, and she's already halfway there. He leaves the neat mounds on their cream supports and pulls her head to his, possessively plundering and bringing her ever closer till she's forced to straddle him, knees on the cushions either side of his thighs.

She certainly isn't objecting to the position, rubbing against him and trying to take friction against the hot weight. He lifts her without effort, just enough that she can't get what she wants without his co-operation. "Wait a little. Anticipation is the best sauce." She growls at him. It's wholly spoilt by the moan in the middle as he slides his hand back between her legs and then lets her body drop again.

He loves knowing he can do this to her: turn her hot and soaked in minutes; that she's so confident and easy with him now that she'll hand over control and herself; that she totally trusts him to keep her secure whatever the game.

"I've got a game for us, Beckett." She squirms over his hand, which is stopping her grinding against him.

"I don't wanna play unless it involves you getting me off. Now." That piece of insolence deserves an answer, but not in words. He moves the tips of his fingers very precisely and listens as Beckett loses her words. Which is also only fair, since she deprived him of his only a few moments ago.

"All in good time. I've got hours of your teasing to make up for." He could just keep teasing her till she's screaming and threatening to shoot him. The thought is very pleasurable – has been very pleasurable, other nights. But maybe there's a better way.

Some fluff in two chapters, for everyone. Always delighted to know what you all think.

This was inspired by a phrase in the property section of Friday's broadsheet newspaper. I'm fairly sure they didn't mean this.