This "first" was born from my fluffy season 5 feels and my endless daydreams about Castle and Beckett having a baby together.

Castle steps onto the elevator and hits the button for the homicide floor, shifting impatiently as the old elevator begins its slow, lurching ascent.

Kate sent him on a coffee run forty minutes ago. There was a new barista at his favorite coffee place and it took her three tries to make Beckett's skim latte. Ridiculous. He knew she needed the caffeine boost (she cherishes those 300 milligrams a day) and now she's probably in the throws of a splitting headache and he hates that.

He steps off the elevator finally, and heads over to her desk, only to find her chair empty. He sets the coffee cups down and glances over to Esposito's desk. The detective catches his eye, the unspoken question, and nods towards the break room.

He pushes open the door, steps in, and stops in his tracks. Kate is asleep on the couch, completely dead to the world. She's lying on her side, knees drawn up to her chest. Her mouth is slightly parted, one hand tucked under her cheek, the other resting low on her belly, palm pressed to the small bump.

He grins and moves closer, crouching beside her head. He reaches out, rests his hand over hers on her stomach, before leaning in and pressing his lips to her forehead. "Kate," he murmurs softly.

She stirs slightly, her eyelids fluttering. He kisses her cheek, the tip of her nose, and her lips, a soft brush of his mouth over hers. She hums in the back of her throat, draws her hand out from under his to reach for him, fingers curling around his shirt collar.

"Hey," she murmurs, eyes still closed, a soft smile on her lips.

"Hey, back," he says, kissing her again, a little deeper this time, slowly drawing her back to the world.

She sighs again and opens her eyes, shifting a little so that she's lying on her back, her face still tilted towards him. "You have my coffee?" she asks.

He nods. "On your desk. Too little too late, it appears."

"Ugh, Castle, I'm so tired," she mutters, pressing a hand over her eyes.

"I know you are," he says and feels his chest tighten because it's true. It was morning sickness for the first couple months, and then heartburn so bad that she could barely sit up, and now insomnia of all things, making her wired at night and leaving her exhausted during the day.

"I feel like all my wires are mixed up," she says, dropping her hand so she can meet his eye—his beautifully blue, worried eyes.

"Babe, you're creating life," he says, grinning a little, smoothing his large hand across her stomach. "It's normal to feel a little off."

She huffs at him, but the edges of her mouth are quirked upwards. "Don't call me babe. And I just want to sleep."

"Okay," he says simply.

She raises an incredulous eyebrow at him. "Okay?"

He nods. "Okay. Let's go home."

"Castle, I can't just leave. I have—"

"No active cases and Esposito and Ryan can handle the paperwork for a day."

She frowns at him, but he can tell she's seriously considering. She's stretched thin, beyond tired.

"I…" She pauses, hesitating, eyes conflicted. "I need to check with the guys first."

"I'll do it," Castle offers quickly, standing up. "You wait here."

She watches him disappear back out into the bullpen and lets her eyes drift shut again, the sleepiness like a drug that keeps pulling her under. She can't ever remember being this tired. Not at the academy, not as a rookie cop in Vice who frequently spent days walking the streets with barely a catnap in between assignments.

This exhaustion is deep and heavy, throbs in her bones, weights her blood, but she doesn't mind. She doesn't mind for the same reason she didn't mind the morning sickness or the heartburn.

It's their baby. They're having a baby together. What is there to complain about?

She smiles at the thought, drifting in and out, the muffled sounds of the precinct filtering through the haze. She's not sure how long she lies there waiting for him, but then he's back, kissing her again, so sweetly and reverently that she honestly could cry.

She's so tired.

"What did they say?" she asks, blinking up at him.

"They said it's fine," he answers, smiling.

She hums in the back of her throat, a contented sound, and wraps her hand around the back of his neck, pulling him close. She presses a quick kiss to the corner of his mouth, fingers sifting through the soft hair at the back of his neck.

"Take me home, Castle."

He insists on driving and she happily relinquishes the keys, sliding into the passenger seat with a soft sigh. She leans back against the headrest and closes her eyes, listening as Castle turns on the car and shifts it into gear.

She falls asleep again on the way to the loft and he finds himself grateful, a tension he hadn't been aware of easing in his chest. It hurts him to see her struggle through her days, constantly fighting sleep, and then to lie down beside her at night and watch her eyes droop but never fall, the strange, insomniac buzz rolling off her in waves.

By some miracle he finds a parking spot in front of the apartment building and turns off the car, puts it into park. She stirs when the motion of the car stops, tilting her head towards him and opening her eyes.

"We here?" she asks.

He nods and gets out of the car, walks around to her side and opens the door. She stands up and leans into his body, pressing her cheek against his chest, her head tucked under his chin. "I'm sorry," he says suddenly, arms tightening around her shoulders.

"For what?" she mumbles, feeling herself melt into him, soothed by his smell and his voice and the firm press of his body against hers. She could fall asleep right here.

"I wish it was easier for you," he says, pressing a kiss to her hair.

"Don't apologize for that," she says, tilting her head back to meet his eye, her voice fierce. She lifts her hand, presses her fingertips to his jaw. "Don't apologize for anything."

He smiles softly, bowing his head forward to kiss her. "Let's get you into bed."

She has never loved this bed so much. She's also pretty sure she's never loved the man lying in it beside her as much as she does right now.

They're lying curled towards each other, eyes open, faces close. "I don't think I've ever seen you fall asleep in the precinct," he says, his voice soft.

"I never have," she tells him. "Not even as a uniform. I prided myself on it."

"Oh, how the mighty have fallen," he says, grinning.

He can just picture her as a stubborn rookie, running on empty, downing coffee like there's no tomorrow. Headstrong, stubborn—staring down sleep and darkness, never allowing herself the luxury of rest.

"That's when I fell in love with coffee," she admits. "Even that awful precinct stuff. How did you describe it? Monkey pee?"

He smiles at the memory. Reaches out to run his hand along her hip under the covers, her skin warm, her body heavy with sleep. "Like a monkey peed in battery acid," he recalls, his voice soft.

"Mmm," she hums. "What a way with words." Her eyes drift shut again, but she lifts a hand towards him, presses her palm to his chest. "I like your coffee better."

He scoots closer, draping an arm across her waist and tugging her into his body. "Can I hold you?" he whispers, his lips ghosting across her forehead to land briefly at her temple.

"Course," she mumbles. "But can we…"

She trails off and shifts away from him briefly, turning onto her other side so that her back is pressed to his chest. She lets out a happy sigh when he presses close again, resting his hand against her stomach, rubbing slow circles.

"I like it when you do that," she murmurs, resting her hand over his.

He smiles, lips pressed to the curve between her neck and shoulder. "I love you," he says simply, the only thing he can think to say because he's so in love with her, so in love that there aren't any other words left. "Now sleep."