Chapter 1: Past Imperfect

She's wearing his t-shirt. His t-shirt. His old t-shirt that he thought he'd hidden well enough at the very bottom of the pile in the closet that she'd never find it. He never wanted her to find it. He never wanted to find it. It doesn't fit. It's two sizes too small for him and he has long grown out of superhero t-shirts (at least where anyone might see him in public).

He actually has no idea why he kept this one. The others have happy sentimental value: the one he'd worn when Black Pawn accepted his first book; the ones he'd had when he'd been happy at school, or another lurid tale published in the school magazine, when he'd been working in vacations and needing to think no further than the pull and play of teenage muscles. All those ones are still in his closet, too, but on the very top of a noticeable pile where Kate can – and does – find them and borrow them and wear them around him with almost nothing – sometimes absolutely nothing, those are… interesting… times – else on at all.

She looks damn good in those t-shirts, and feels even better. He knows when he sees her in nothing but those t-shirts that she's feeling playful and mischievous and teasing, and that she will shortly slither up to him and twine her arms around his neck and kiss him, and then he'll catch her up – because he loves proving to her that yes, he really is big enough to pick her up and carry her and toss her on to the bed (or the couch, or lay her out on his desk) - and investigate the contents of the t-shirt slowly and carefully and in detail. He loves it when she wears his t-shirts. He loves sliding his hand up the exposed length of her leg till she wriggles and presses against him; he loves how the soft, sloppy cut falls against her form and moves as she does, revealing and concealing in turn.

This t-shirt is entirely different. This is not a t-shirt full of good memories and happiness, ratty from long use and comfortably stretched and pulled. This is a t-shirt that's practically pristine, worn precisely once and never again, imbued with sadness and remembrance of times past, times lost. This is the t-shirt that he'd worn standing in the middle of Grand Central Station, listening as the only girl who'd ever walked away from him told him – gently, it didn't help – that she was leaving. He'd never had a hint of it. His Kyra, support, encourager, lover – gone. And he, left standing there after she'd kissed him goodbye, in this t-shirt that he'd bought the day before from some cheap stall down on Canal Street because he'd thought it was appropriate: Peter Parker and Clark Kent, and a caption My alter ego's a superhero. Cheesy, but he'd liked it at the time.

And now Kate's wearing it, with an expression that suggests very strongly that there's not a stitch of clothing underneath. Or at least she'd had that expression. It's currently running off her face like paint from a watercolour left in the rain. This is still all so very new, and she knows something's wrong but she doesn't know what it is and she's pulling back and shutting down and oh shit she thinks it's her. Correction. She knows it's her.

"Where did you find it?" He didn't mean to add that unhappy tone, either. Kate's eyes flash with answering, disconcerting, upset.

"In the closet, just like where I find all your t-shirts. Is there a problem here, Castle? I thought you liked it when I wore your t-shirts." Uncertainty is bleeding through her voice as she looks at him. She's turning away, through the study, back to his bedroom, closing the door. Shutting him out, or herself in. Walking away. By the time he gets there the t-shirt is on the floor, and the bathroom door is closed and, when he tries it, locked.

This is not a good start to a weekend on their own.

He picks up the t-shirt and sits down on the bed, burying his face in the cotton. It smells like Kate. She must have put it on straight after her shower, and it's absorbed the scent of her bodywash. It doesn't wash away the memory.

The bathroom door unlocks, and Kate emerges, wearing her own silky tee and jeans, still looking deeply uncertain. Actually, Castle realises, she looks deeply hurt. Not that she'd tell him that. He's hurt her. She knows something's wrong, she doesn't know why, and she's jumped to the conclusion it's all her fault.

"Kate…"

" 'S okay. I shouldn't have borrowed it." He can see the next sentence rising in her throat. Sure enough… "I'll not borrow them again." She hasn't even come to stand, or sit, beside him. "I'm going to get something to drink. Do you want something?" She's turning away, walking away. Just like the last time someone wore this t-shirt.

"Don't go away." Something in his tone hits her. She stops, hand half out to the door.

"What's up, Castle?" Uncertainty and hurt is turning to concern. She turns back.

"I like you in my t-shirts. You can borrow them any time you like." A swift smile, heavily tinged with leer, flickers across his mouth and disappears again. "It's just this one. I don't like this one."

Kate sits down on the bed next to him and puts a tentative hand on his knee. Castle turns his face into her and hugs her hard, hiding his face in her neck, t-shirt forgotten beside him.

"What's wrong with this one? The design's a bit second rate, but compared to most of them it's practically new. Did you grow out it before you wore it?" Castle winces. That's inadvertently painfully accurate. Mentally, precisely so. He presses further into Kate, who brings both her arms up round him and holds him close, patting him consolingly on the back.

"Why don't you like it?" She picks it up, looks it over critically. Her gaze snags on the label. That's interesting: this one's a larger size than the others. Castle must have been a bit more filled out. Older? Her detective instincts twitch. Castle's still nuzzled into her shoulder. Instinct and training take over. Slightly older. Utterly miserable about it. Only two options, really. Kyra, or Meredith. A small flame of jealousy takes light. He's hers, now, and she is not having him moping over other women. Especially if it turns out to be that red-headed, irresponsible idiot. Not that she'd be dead keen on it being Kyra, either. Even if Kyra is happily married and not interested in Castle at all, any more. She doesn't share. She's certainly not sharing Castle. Oh no. They've wasted quite enough time with other people – dead-end relationships – that she is not having memories of them get in the way.

"If you don't like it, why did you keep it?" There's a miserable mutter into her shoulder. "Why, Castle?"

"I-thought-she'd-come-back. But-she-didn't." Kyra, then. Meredith's been back and forth like she's on elastic ever since Castle got rich and successful. Well, that elastic can just be snapped. Maybe it'll slap back into Meredith's expensively Botoxed face. Anyway. She doesn't need to worry about Meredith. And she'll just make damn sure that Castle stops moping over Kyra. Oh yes. She pushes Castle gently off her shoulder and backwards so he ends up flat on his back sprawled across the bed, his legs dangling over the side, looking both miserable and confused. Well, she is going to fix that. Oh yes. By the time she's fixed it there will be no room in his head for anything let alone memories of other women.

Beckett acquires a feral, predatory look that terrifies Castle. He's no idea what she's planning, but he's surprised himself, never mind Beckett, (she doesn't look like a Kate right now, she looks like bad-ass Beckett, and he thinks he's her prey) with the strength of his upset and emotional reaction to the memories that this particular t-shirt has revived. Or re-animated. Zombie memories, dismembering him. It's perfectly possible that Beckett is intending dismembering him, not at all metaphorically, for spoiling what they had intended to be a very private weekend. And it was he who's spoiled it.

Beckett is still regarding him with that terrifying expression. When she stands up, he's sure she's walking away from this scene. He is, therefore, considerably surprised – to the extent he can manage through the cloud of old, stale misery – that she moves round, pushes his knees apart and stands between his legs.

"Look. At. Me. Castle." He does precisely what he is told. The bite of authority takes control of his brain and leaves him obedient to her will. Half a second later, when her hands slide slowly over her torso from shoulder to hips, smoothing her top over her breasts in a way that leaves simultaneously nothing and everything to his imagination, he doesn't need obedience. That virtue has been completely replaced by the vice of lust. The result is precisely the same. His eyes are riveted to Beckett.

She doesn't say another word. She slides her tongue smoothly over her lips, and her fingers to the button of her jeans. As her tongue retreats to safety, the button also slips out of sight. Castle gulps. The zip opens, slowly. Beckett smiles sharply. Her hands move to her hips, and her thumbs slide under the waistband. The jeans drop an inch. She licks her lips again, and brings her hands around a little more to the front. Another inch, then two. Her thumbs are now sliding down the front of her hipbone. Castle draws in a hard breath and starts to lever himself up. Beckett leans over and shoves him back down.

"You don't move, Castle. You stay right where I put you till I tell you you can move."

The jeans drop further. Castle can see the edge of lace clearly, now. Blue, today. Parts of him are beginning to feel rather blue, too. And not the parts that felt so earlier when he first saw that t-shirt, either. That had been his brain. This is considerably lower down. Isn't torture illegal under the Geneva Convention? Maybe he should draw up some rules. The Broome Street Convention. Rule One: no torturing Castle. Beckett's thumbs are skirting the edge of some areas that he was intending to pay delicate and persistent attention to, this weekend. In consequence, the jeans are reaching the point of no return – ah. There they go. Ohhh. He likes that view. All five miles of legs. And he'll like the view at the top of them, though disappointingly it hasn't yet been revealed.

He likes it even better when Beckett slowly divests herself of her t-shirt to reveal the other half of the blue lace. This one is pulled taut over her breasts and is not concealing her erect nipples in any way at all. He'll play with those later. Soon. Now. Rule Two: no telling Castle not to touch. He has another try at sitting up. Beckett glares and suddenly places one knee very precisely on his thigh, where a movement of an inch would incapacitate him. It's clearly a warning. He lies back down again. Quickly. The knee leaves. Rule Three: no threatening Castle. He'll impose these rules. In his dreams. Beckett's not notably keen on him imposing rules. Well, except… ooohh yes. Except. His miserable mood is quite gone.

And then she picks up that t-shirt. She looks at it with a victor's smile, satisfaction edging every one of her excellent lines – and puts it on. Castle's jaw drops. His good mood is leaking back out his ears into the sheets.

"What…what are you doing?"

"Shush. No talking. No moving. You do nothing till I say you can." Her tone reverts to that spine-straightening command-voice. "Look. At. Me." He does. "Look at me in this shirt." She moves with the boneless flexibility of a large cat – a panther, perhaps, perfectly midnight black and perfectly lethal – and the bra drops to the floor. She needn't say anything more. Castle's back to being riveted to her body. She did that without revealing anything. She didn't need to. His imagination hits turbo-charged overdrive. He realises his breathing is hoarse and choppy. He's painfully aroused. And he is fully dressed and Beckett is – not.

"What do you see in this shirt?" He can't answer. He's too busy trying not to whimper. Eventually he forces out a word.

"You." She nods once, sharply.

"That's right. You see me."

And then she slides her hands up under the t-shirt and oh oh oh the hem lifts but not as far as Castle would like and the only thing in the world at that moment is Kate Beckett who he loves, and the t-shirt that he hates, and her panties dropping to the floor. He can't move. He can't think.

"What do you see now?"

"You. Just you. Please, Beckett, come here." She smiles diabolically.

"No. I want my dinner." She slinks to the door. Castle's eyes don't leave her ass for a second. Knowing she's wearing absolutely nothing under the t-shirt is killing him. "You coming, Castle? I'm hungry." Oh God. He is hungry. He is starving. But it has absolutely nothing to do with food. Rule Four: no stopping for dinner. In fact, Rule Five: no stopping. He struggles off the bed and follows.

Beckett is rootling in the kitchen cabinets looking for plates and not incidentally stretching just enough that the edge of the hem is perilously close to the swell of her ass. She can feel Castle's hot, intent gaze on her. But she is by no means finished with him. Thinking pitifully about past girlfriends? Well, she is still not having that. There's only one woman he'll be thinking about. Now or anytime soon. Well. Now or ever. She can sense him sneaking (ha! Castle can't sneak. It's not in his nature) up behind her.

"Get back, Castle." There's a disgruntled whimper.

"Ka-ate."

"Go and sit at the table." She hears him comply. She stretches again, and listens with satisfaction to the indrawn breath. Almost a gasp, really. "What do you see, Castle?" It's an order, demanding not requesting a reply.

"You, Beckett." That's right. Beckett. Hard-ass Beckett, in command. She'll bring Kate back later, when he's … reprogrammed.

"Wearing?"

"My t-shirt. You wearing my t-shirt."

"And? What else am I wearing?" That's definitely a gasp.

"And nothing else. Come here, Beckett."

"No. I want my dinner. Aren't you hungry too, Castle?"

Dinner appears on the table. Castle is almost clinging to the chair to stop himself simply hauling her up and on to the counter and ignoring eating dinner in favour of devouring Beckett. But he knows that when she's in this mood disobeying her is not a good plan. In other moods, now, it's she who obeys, and they both like that too. But that's not for now. Right now, he's looking at Beckett in a t-shirt that had had only unhappy memories but which is rapidly acquiring some connotations that are anything but unhappy. She's sitting down opposite him, smirking, and that is simply unkind because he'd had some plans for running his hand on to her knee and up her leg and round to that amazingly silky-soft skin at the tops of her inner thighs and teasing her as she's teasing him oh shit what is she doing? Her bare foot is sliding over his pants and up over his knee and his thigh and he hadn't exactly recovered from the sight of Kate Beckett letting her underwear fall and now she's making sure he doesn't and ohhh her toes are almost as wicked as her fingers.

He catches her foot before she can withdraw it and scrapes a hard fingertip over the arch and watches her wriggle and her eyes widen and darken, follows that up by running his hand over her ankle. She touches her tongue to her lips and smiles wickedly.

"See something you like, Castle? Tell me what you see." He knows what she's doing. He knows that she's sometimes jealous. He loves that. He loves knowing that Beckett, bad-ass, hard-ass, all-round alpha female, can be jealous of other women. Not that she has any need to be so: there's no-one else for him. But it produces such very interesting results. This time, it looks like she intends the result to be a very different memory of this t-shirt. It's already working. He should, he supposes, be just a little concerned that he's so easily dispossessed of a trigger to such a critical memory. But all he can think about is that he has Beckett's ankle in his hand and that if she were only next to him he'd slide his hand all the way up her leg and not stop and that's Rule Six: Castle gets to play.

This is from a prompt that Mobazan27 sent me. Hope you like it. Some fluff, in two chapters. Conclusion tomorrow.

Always delighted to know what you all think.