Welcome to Fantasy Fridays! Hold on to your knickers - this series of one-shots is going to get spicy. I'm hoping to post a chapter each week. Although my plan is to have a (light) thread of character development/plot running through these stories, each chapter should be able to stand alone. I've got a long list of ideas and am always open to more! Reviews, follows, and favorites feed the fairies of my inspiration, so don't be a stranger!

This introductory chapter takes place right after 5x17 - Scared to Death, in the early days of Castle and Beckett's relationship.

WARNING: If you're not comfortable with M-rated stories, please hit the back button.

Fantasy Fridays
Chapter One: A Different Kind of Bucket List

The ice is melting.

Beads of condensation merge together and slide down the sides of the whiskey glass in Castle's hand, pooling between his thumb and forefinger before seeping past to soak into the comforter. They'd been too desperate to pull the sheets back.

Castle's muscles are gelatinous; it takes all he has just to keep the tumbler from falling and shattering on the floor.

Fucking hell, the woman was not kidding about the ice cubes.

Kate returns from the bathroom and grins at the sight of her very naked, very limp partner sprawled on the bed.

"Castle, you haven't moved for at least ten minutes."

"Can't," he mumbles. "All fucked out."

Kate ties the silk sash of her robe and perches at Castle's hip. She spots the precariously balanced whiskey glass in his hand and leans over him to move it to the bedside table. Castle's other hand meanders up her thigh, slipping beneath the cool material, and he murmurs something she can't quite make out.

"Use your words, Castle."

"Mmm … Look good … n'purple."

"Thanks for the compliment, Casanova. And don't pretend you like this robe for any other reason than its inability to stay tied." She leans down and applies a soft kiss to the corner of his mouth, letting her breasts brush against his chest.

He musters enough energy to pry open an eye and concludes happily that the sash is definitely falling asleep on the job.

"There may be another reason I like that robe."

"And that would be?"

"It's very short." He squeezes her thigh. Hard. The tension he'd banished to her fingertips only minutes ago starts to wind back onto the tight spool in her stomach. God, this man, already winding her up again. Well, technically, he's been winding her up for years; she just enjoys this new type of winding a little bit more. Aches for the moment the thread breaks and leaves her in a tangled, messy heap.

Kate slides down the bed and fits herself against the terrain of her partner's body. She lets her fingers drift up and down the soft curve of his side. Her nails leave a trail of goosebumps when she drags them over the hard ridge of his pelvic bone.

"You know, Castle, your bucket list was way more PG-13 that I thought it'd be."

"Oh? I'm a pillar of virtue, Beckett. What sort of filth did you expect?" He's exhausted, his voice impossibly low, and she loves it.

"Oh, I don't know. Just thought that by now you'd have a long list of things a certain writer has been wanting to do with a certain law enforcement agent."

"You know for a fact that Nikki and Rook have an admirably healthy sex life, but if you want to know what my wildest fantasies are, Detective," he pauses, and she shivers at the indescribably sexy way her professional title rolls off his tongue, "all you have to do is ask."

"I think I have a better idea." Her fingers can't resist the magnetic urge to touch him where he's already firming for her. She wraps her hand around him and strokes slowly from base to tip, eliciting a dark, gravelly moan. "What if we institute a new tradition? We take turns telling each other one fantasy each week."

"Ooh, can we make it a rule that the other person has to accept?"

"Not sure that would be very safe."

"Why, Detective Beckett, what are you insinuating? That your list has something on it that might be too filthy even for me?"

"Not exactly, but I'm fairly sure your fantasies are going to include more illegal activities than mine. And more opportunities to get caught."

Suddenly, her voice drops to a whisper, infused with an honesty he never thought he'd see from her. "But I'll do my best to make your dreams come true."

"And you're sure you don't want to just exchange lists up front?"

"More anticipation this way. And if anyone can appreciate a little anticipation, it's us," she smiles. "If we read them all at once the mystery would just … be over."

Castle tucks this piece of Kate away deep inside himself. It reminds him of how she eats M&Ms, meting out her pleasure just a few pieces at a time, storing half of them for another day. He always tears the end of the bag clean off, tipping the candy into his mouth in an avalanche of chocolate. He usually regrets it five minutes later. Lately he's taken to buying two bags at a time from the vending machine at the precinct. Or three.

"I think it's an amazing idea," he beams at her. "Your filthy little ice cube trick - and it is filthy by the way - has been one of my fantasies since the day you mentioned it, so consider tonight our inauguration. You get to choose next week's fantasy."

Kate can almost feel the idea bubbling in his mind before his next words come out. "Hey! Since today's Friday, can we call our new tradition Fantasy Fridays?"

"Sure, Castle. Although I thought you'd want to call it Fuckit List Fridays."

"Oh my God, you are the best girlfriend ever."

Thoughts?