Many Thanks to TR-Fanfic, for proofreading and helping with flow and words when I got stuck.

AN: This is set after the "Setup" and Countdown" arc (episodes 3x16 and 3x17, in which Castle and Beckett almost freeze to death in each other's arms in an enormous ice box, then have to find and diffuse a bomb that threatened the city.)

Thaw

The knock is quiet, reluctant.

"Hey, Castle," she greets him when he swings open his door. Her voice is low, an insecure timbre threading through her words. Her sweater is too large, the sleeves reaching past her knuckles; she kneads her fingers peeking out from under it.

He didn't expect her visit, but he isn't going to question it. It has a dream-like quality, this appearance of Kate at his doorstep, late at night, and he fears that if he asks, she will vanish, simply disappear into the night again.

Instead, he beckons her inside. "Come on in."

She steps over his threshold, stops in the entryway. The loft is warm, the heat on at full blast, a large fire dancing in the fireplace. But a blanket is draped over his shoulders nonetheless.

"Couldn't sleep?" He asks her and she shakes her head, no.

"You?"

He points toward the couch. "I was channel surfing."

She nods. Kneads her fingers again as they stand in his entry in awkward silence. She feels shaken still; she'd pushed through when she needed to, as she always does. Adrenaline kept her going, made her fearless, but in the quiet of her home it all swirled around her, closing in on her, and it propelled her forward, over here toward the steady chatter of his voice, toward his warmth.

"Can I stay for a while?" She blurts out, because this is where she needs to be, because he is here and he knows; he's the only one who understands. She shivers, rubs her hands up and down her arms to dispel the chill.

He nods once, steps closer, then guides her toward his living room, his hand hovering by her lower back, not touching her.

"Josh?" He instantly berates himself for asking; he doesn't want to know because he feels punched in the gut every time he sees her with him. But he is worried about her and so he can't not ask.

She glances at him from the side, finding nothing but sincerity and concern in his eyes. She shakes her head decidedly.

"Beckett, I'm s…" but she lifts her hand, holds up her palm vertically between them to stop his words. She doesn't want to hear it, or talk about it, because if she does she would have to admit that it had been a long time coming and she ignored it. Didn't want to see it.

She sits down in one corner of the couch while he brings another blanket, drapes it across her shoulders. Grabbing the edges, she wraps it tighter around her torso, curls up with her legs drawn up onto the seat cushion.

He takes the other side of the sectional, continues channel-surfing and for a while they sit silently, allowing the mindless chatter of the TV to drown out their thoughts.

"I'm so cold Castle," she admits suddenly. She shivers, looks over at him. "I just can't get warm anymore."

He knows this; the penetrating cold of the freezer seeping into muscles and bones, the heaviness spreading like lead through his bloodstream, the abject fear when he couldn't move, couldn't help her, had to watch her fade in his arms.

"Come on," he gets up, extends his hand to her. She looks up at him, her eyes big, questioning, shining in that shimmering light brown, like brandy in firelight. His gut clenches forcefully.

"You trust me?"

She contemplates him for a moment, then nods, and places her hand in his.

He leads her through his study, then the bedroom until they reach his large bathroom. It might be slightly crazy, this idea he had, yet she follows him, asks no questions, simply leaves her hand resting in his.

He leaves her standing in the middle of the room, and she curls her toes against the large plush bath rug. She watches as he turns on the water, running a bath in the oversized Jacuzzi tub built into a corner of the room. Steam starts billowing, forming swirls and curls above the surface of the tub, blurring the details of his features when she focuses on his face.

"I'll be right back," he says, heading toward the door. And she doesn't know what to do next, so she just stands, in the middle of his bathroom, within the surreal glow of steam and overhead lights. The warm moist air curls the hair around her face, and her tummy flutters. She realizes that for once, she doesn't want to bolt, she doesn't want to overthink; she just wants to be… warm.

He comes back in, steps close to her, handing her a tumbler of whiskey. She accepts it with her fingertips, swirls the glass, watches the amber-colored liquid slosh along its sides. The rich fragrance rises to her nose, and she lifts the tumbler to her lips, and knocks back the shot.

The heat of the strong drink jolts through her limbs, and when he turns to leave, she reaches for him, grabs his sleeve, can't bear the thought that he'd leave her now. He turns back toward her, questions on his face.

"I'm so sick of this cold," she confesses, her voice raw, gripping his wrist. The water still thunders into the tub, drowning out the silence and her racing thoughts. She steps closer, lifts her eyes up to his.

"I know you're cold too." She states it almost matter-of-factly, when it's anything but. While she reaches up, slips open the top button of his shirt.

The blood is pounding in his ears. He grabs her wrist, presses her wandering fingers against his chest.

"Kate?"

She lifts her eyes to him, and there, within their depths, he can see everything he needs to know. She asks for what she needs, for his trust, for him. And he will give her whatever she needs.

He frees her hand and, still holding his eyes with hers, she works her long fingers down his shirt, makes quick work of the rest of the buttons.

"Why didn't we think?" She questions and skims her hands back up to his shoulders, slides off his shirt. Why is he shivering when his skin is so warm?

"You fight hypothermia with body heat," why did they just sit there, why wasn't she in his lap, why didn't he wrap himself around her tightly? They'd gotten so careful, so afraid of the wrong step, that they almost died without… There goes his belt, clicked open and quickly pulled out from the belt loops of his pants and dropped to the floor, joining his shirt.

She shivers when she reaches for his button and grazes the skin below his navel with her fingertips. It is because she is so cold, she tells herself. And she needs to warm up. With him.

"We didn't think!" She scolds, but her touch is gentle when she opens his zipper. His pants drop, and she divests him of the rest of his clothes in quick succession. Then she rises to stand in front of him, lifts her hand to his chest, feeling the thunder of his heartbeat underneath her palm.

"Body heat," she nods.

He steps into the tub first, making sure the water won't be too hot for her chilled skin, then hits the switch for the bathtub heater to keep the temperature up. While she takes off her own clothes and he purposefully doesn't look. He feels slightly out-of-sync with himself, like having mental whiplash, but he has long since accepted that when it comes to this woman, there are always surprises. He loves that, loves her strong mind, her fire, her unpredictability.

And then she turns around, proud and strong and gloriously naked, and he feels like he can't breathe. His heart is too full. He's never imagined his first glimpse of her would be like that, but it's perfect; she's perfect.

He holds out his arms to her and she accepts them, gracefully climbs into the tub. He'll never stop being amazed how much strength is encased in her long, lithe limbs; how she feels fragile to his touch, belying the power of her sinewy muscles underneath.

"Is this okay?" He asks when she lowers herself in the water.

She settles between his legs, turns her body around toward his. The water sloshes as she moves; she slips her hands around his torso, her chin against his sternum as she looks up at him.

"Castle…" She spends a moment just taking him in, her eyes luminous, her irises now sprinkled with flecks of warm green. He loves her eyes; they show all her emotions, if only she lets him see her closely enough.

"It's perfect."

He exhales sharply, wraps his arms around her back, pulls her tightly against him, his fingertips pressing against the ridges of her ribs.

She rests her cheek against his chest. Breathes deeply, listening to the steady rhythm of his heart, getting drowsy from the alcohol in her blood, the hot water around her and his warm strong body underneath. This… this is what she needed. This warmth. This man. Her arms contract around him, holding on tighter, and she closes her eyes.

He runs a hand through her hair, caresses her scalp with slow circles of his fingertips. Listening to her breathing even out, feeling her body relax against his, he too settles, his eyes falling shut.

And they sleep.