DAY AND NIGHT
POST-3x06 AU
RATED M

Day and night, it's always you inside my head.
-unknown

She can't sleep.

She did at first, had collapsed on her couch after getting Castle's official statement and driving him home before dragging herself to her cold, empty apartment. But she'd woken with a start just a short time later, panic settling in her chest.

She almost lost him.

All of them had missed the now-obvious identity of 3XK, and while she knows Castle will feel the guilt for a long time - Tyson made it personal with him - as the lead detective, the blame sits squarely on her shoulders.

If Tyson had done more than tie Castle to a chair, if he'd hurt him, or worse, she doesn't know if she could live with herself.

She grabs a bottle of water, and as she passes her couch to try and get some more sleep in her bed, she hears her phone beep from the pile of blankets that she'd kicked aside.

Considering the hour, she probably should be surprised to see a new text from Castle. But she isn't; in fact, she would've been more surprised if he wasn't awake.

She opens the text, her lips quirking when she reads his words.

In case I didn't say so earlier, thanks for coming to get me.

If they were together in person, she'd make some quip about wanting to avoid paperwork, just to add some levity to a gravely serious situation. He'd probably get her sarcasm over text, but he'd been so down earlier, so serious, that she doesn't want to risk it.

She starts to type a few responses, deleting each one until she finally takes a deep breath and sends something that she probably wouldn't say if she wasn't hiding behind a screen.

I don't know what I'd do if something happened to you.

She watches as dots appear and disappear several times - he's probably doing the same thing she did - until finally his reply appears.

Do I sense a shred of concern for my well-being, Detective?

She rolls her eyes.

I'm serious, Rick.

She jumps when her phone rings in her hand, Castle's picture - when did that happen? - appearing as he calls. She briefly considers ignoring it, but, well, she doesn't have a good excuse since she literally just sent him a text.

She swipes to answer, and before she can greet him, he's talking.

"I'm serious too," he says in a low husk that sends shivers down her spine. "I knew you'd get there eventually, but sitting there, tied up, I started thinking the worst."

She takes a shaky breath. "Rick…" She whispers. "Of course I wouldn't let anything happen to you."

"I know."

The anonymity of a telephone call makes her brave, and she heads towards her door and reaches for her coat. "Can I come over? I want to see you."

He chuckles, and if she didn't know any better, she'd think she hears it echo. "Open your door, Kate."

She pauses, her hand outstretched, then takes a deep, calming breath and unlocks the deadbolt. She curls her fingers around the handle and opens the door.

His eyes locked on hers, Castle ends their call with a tap of his thumb and slides his phone into his coat pocket.

Her heart hammers in her throat as she sets her phone on her side table, and she watches Castle's eyes darken and drop to her lips. His tongue darts out to wet his bottom lip, and she barely has a chance to register that he's moving towards her before his hands are cupping her jaw and his mouth is on hers.

She melts into him, her arms circling his waist, a quiet moan escaping when he pulls back for a breath. Her fingers grip the back of his jacket, holding on as he walks her back and kicks the door shut. She winces at the loud slam, but then he's turning them, pinning her against the door, one hand leaving her jaw to quickly lock the door before he buries his fingers in her hair.

She tears away with a gasp, and he takes advantage, trails his mouth across her cheek, nips the tender skin under her earlobe before making his way down her neck. The collar of her oversized sweatshirt slides off her shoulder as she arches her back, and he kisses along her collarbone, his tongue and teeth marking her, driving her wild with desire.

He grips the bottom of her sweatshirt, and she pushes him away long enough to draw it over her head. He rids himself of his coat and t-shirt, and they both take a moment, their identical dark gazes traveling down the other's naked torso.

He reaches out and hooks a finger in the top of her leggings, and she surges into him, sinks her teeth into his bottom lip before soothing it with the soft press of her mouth to his.

He grunts, his hips bucking, and he slides his hand down the front of her leggings. His finger teases her slick folds, and he groans, the noise coming from deep in his chest and going straight to her core.

"Fuck," he growls as he circles her clit, "God, Kate, you-"

She circles her fingers around his wrist and pulls his hand away before she gets too caught up in his touch. Without a word, she laces her fingers through his, heat rushing across her body at the feel of herself on his skin, and she leads him into her apartment.

There's a gentle tug on her hand when they reach her bedroom, and she turns to find Rick gazing at her with a tender look in his eyes that contradicts the mischievous quirk of his lips.

"Do you still sleep with a gun?" he teases, peeking behind her.

She purses her lips in mock thought. "Give me a reason not to," she jokes.

He narrows his eyes and grabs her hips, tugging her into him, his erection pressing against her.

"Oh," she gasps. She palms him through his sweats, her mouth watering as she maps him with her fingers. She dips her hand under his waistband and curls her fingers around him, and she gives him a few long, lazy strokes, grins when he moans and drops his forehead to her shoulder.

"Speaking of guns," she teases in a low husk, swiping her thumb across the tip.

He laughs, his breath wafting along her skin, and he takes a step back, out of her reach. "That was a terrible line."

She smirks and gently nudges his chest, leads him into her room. Leaning back when he grabs her waist and tugs her into him, she sighs and covers his hands with hers, holding him to her, closes her eyes as his mouth trails along her shoulder and up her neck.

He grinds his hips, and she gasps as his erection presses against her ass, rolls her own hips in a wordless plea for more. They move towards the bed in unison, his mouth never leaving her neck, his fingers dipping into her leggings.

She gasps when he cups her breast with his other hand, and he brushes his thumb across her pebbled nipple at the same time he presses his fingers to her clit. Her hips buck into his touch as new arousal aids the work of his hand between her legs. She reaches behind her and cups the back of his head, twists her neck so she can bring his mouth to hers.

It's little more than a meeting of mouths, shared gasps and echoed groans as she rolls her hips, as he rubs, dipping his fingers through her arousal, finally burying two fingers inside her and grinding his heel against her clit. His other arm wraps around her waist, holding her to him as she breaks apart with a cry.

She drops her head back to his shoulder, turns to the side as he kisses up her neck, pausing to scrape his teeth along her pulse.

"I wanna see you," he husks, his mouth next to her ear, tongue darting out to taste her skin. "I wanna taste you, watch you come over and over again."

She turns in his arms, immediately misses his hand between her legs when she does, and crashes her mouth to his. She tugs at his waistband, shoving his sweats down his legs, and when his erection springs free, she steps back just far enough to look down at him. She grips him again, this time watching as she strokes, slow at first, speeding up when his breath quickens and his cock twitches.

"Fuck," he groans, cupping her jaw with one hand. He lowers his mouth to hers, sweeping his tongue between her lips, their tongues tangling as her strokes find a rhythm that has his hips pushing into her touch.

After just a few moments, Rick steps back, moves her hand off his cock. "I can't-" he gasps. "Too much."

She smirks and turns away just long enough to pull the sheets down on her bed. There's a rustle of fabric behind her, and when she turns back, Rick's completely naked, his pants and shoes kicked off to the side. She smirks and hooks her thumbs into the side of her leggings, starts to draw them down when he stops her with a forceful "no."

"That's my job," he says in a low voice, crowding her against the bed until she has no choice but to sit.

Her gaze drops to his cock, hard and thick and right in front of her mouth, but before she can make a move, he nudges her shoulder.

"Lie back."

Her entire body goes hot, and she does as he says, arranges her pillows under her head, parts her legs in invitation. She watches as his eyes follow her movements, lingering between her legs, licking his lips when her hand drifts down her torso.

"Do you have condoms?"

His question takes her by surprise, and she freezes, her hand inches from her pants. "Um…" Her mind races; when is the last time she bought any?

"I didn't bring any," he continues, his cheeks flushing. "I didn't come over intending for this to happen. I just…" He sighs and runs his fingers through his hair. "I'll run out and get some."

She sits up and grabs his hand, stopping him before he picks up his pants. "Wait. Maybe…" She pauses, then shrugs. "Maybe we don't need them."

He sits next to her, and she shifts to face him. "You mean…"

"Yeah," she finishes. "I mean, I take birth control, and I'm good. I'm clean," she clarifies, her cheeks burning. "So, if you-"

"I am too. Clean, that is. Not the birth control part," he teases. He grows serious, and he takes her hand, laces their fingers together. "I can show you my last test results if you want."

She smiles and presses her palm to his cheek, then leans forward and brushes her lips against his. "I trust you," she whispers.

His eyes search hers for a long moment, and then his mouth is on hers again, his tongue slipping between her lips, and he's lowering her to the bed.

She hooks her leg around his thigh and rolls her hips, desperate for friction, for relief.

He grunts and tears his mouth from hers, grinds his groin against hers. "Off," she gasps, sitting up and tugging at her leggings.

Desperate hands paw at her waistband, and she scoots back to the headboard as he pulls her pants off and throws them to the side. She settles against her pillows again, draws her bottom lip between her teeth as he leans back and gazes at her, his eyes dark with desire.

"Fuck, you're gorgeous," he rasps, sliding his palms up her legs. He presses the insides of her thighs, nudging them apart, teases her folds before moving to hover over her.

She wraps her arms around his waist, lifts herself and crashes her mouth to his. Her fingers dig into his back when his cock slides through her folds and drags against her clit, and she whimpers and rolls her hips, wanting - needing - him inside her, immediately.

He props himself on one elbow and reaches between them, grips his cock and lines it up with her entrance. He starts to push in, but pulls away when she tenses.

"What's wrong?" He cups her hip and slides his hand up her side. "Did you change your mind?"

She shakes her head before he even finishes asking his questions. "Nothing's wrong. I just-" She looks over his shoulder, embarrassment warming her cheeks. "It's been awhile," she admits quietly.

He chuckles and tilts her face towards his again. "For me too. Do you want to stop? Slow down?"

"No." She reaches up and covers his hand with hers, her fingers almost perfectly slotting between his. "Don't stop."

His eyes search hers, concern furrowing his brow, and her heart swells with…

Is that love she feels?

She palms the back of his head and brings his mouth back down to hers, and this time when he guides his cock to her and starts to push, she relaxes, hooks her leg high on his hip, and lifts herself into him.

They both groan as he enters her, and she drops her head to her pillow, her eyes closing in pleasure as he slowly slides out, speeds up as he slides back in. Her hips lift into his with every quickening thrust, her arms wrapping around his waist, hands gripping his shoulders as he moves in her.

He swipes his palm across her forehead, pushing back her hair, and he presses his forehead to hers, his quick, labored breaths matching hers. Her name falls from his lips on a gasp, and their mouths crash together in a desperate need for contact.

An orgasm rushes through her, taking her by surprise, and she digs her fingers into his skin as she trembles. His thrusts quicken even as she spasms around him, and he props himself on his hands, breaking their kiss, his dark eyes locked on hers.

She tries to keep her eyes open, wanting to watch him as he comes, but he shifts and presses his palm to the inside of her knee and lifts, opening her for him even more, and she throws her head back with a cry, another orgasm hovering close, so close.

"Rick," she gasps, "please."

She doesn't know what she's asking, if she wants him to stop or keep going forever, but then his hand is between her legs, fingers rubbing furiously at her clit, the slickness from her two orgasms almost too much.

"One more," he grunts, his mouth on hers. "Kate. Fuck. With me." He trails his mouth down her neck, his breath coming out in short pants, the rhythm of his hips faltering.

She feels him swell inside her, and his loud groan echoes in her ear as he buries himself deep and pulses with his release.

She didn't think she had another in her, but her hips roll against his, the frantic work of his fingers coaxing the orgasm from her even as he comes. Stars explode behind her eyes, her head falling back into the pillow, legs trembling as the dam bursts.

She shakes her head and tightens her grip on his shoulders when he moves to push off her, offers him a small, embarrassed smile at his confused look.

"Won't I squish you?" he asks, his voice hoarse.

She chuckles and shakes her head. "I don't mind."

He smiles and takes her mouth in what quickly turns into a heated kiss. He's still mostly hard inside of her, and usually she'd be ready to go another round. But three orgasms in relatively short succession, while wonderful, tired her out, so when his hips begin to slowly move, she breaks their kiss and sifts her fingers through his hair.

"I just need a few minutes," she admits, rolling her eyes when he grins. "Yes, you wore me out, don't let it go to your head."

Rick chuckles and lowers his mouth to hers, kisses her briefly before moving off her. She whines in protest, but he wraps his arm around her and guides her to press her body against his side.

She drapes her leg over his, curls herself around him as he holds her close. The slow rise and fall of his chest is soothing, comforting, a reminder that he's here, he's alive.

He's alive.

She doesn't realize she's crying until he shifts under her and brushes his thumb across her wet cheek. She looks down at his bare chest, wipes away the wet spot from her fallen tears. "Sorry," she mutters.

"Not necessary." He shifts to face her and cups her jaw, traces her cheek with his thumb. "What's wrong?"

She shakes her head, but he just stares, and she signs and leans into his touch. "You could have died," she whispers.

He nods. "But I didn't." The corner of his mouth lifts. "If I did, you'd bring me back just to kill me again."

She rolls her eyes, and he trails his hand down her arm, tangles their fingers together. "I'm not going anywhere," he assures her, his concerned gaze locked on hers. He lifts their joined hands and brushes his lips across her knuckles. "I'm in love with you, Kate. I have been for a while."

Kate tugs her hand from his grasp and presses her palm to his cheek, and she knows without a doubt what she felt earlier.

"I love you too," she admits, her voice cracking with emotion.

Rick grins, his whole face lighting up, and he rolls on top of her, settles between the welcoming cradle of her hips again. "Yeah?"

She can only nod before his mouth is on hers again, his tongue sweeping inside, and it isn't long before they lose themselves in each other once more.

-FIN-