A/N: Inspired by a prompt from castlefanficprompts, to be posted at the end of the story.

Sunlight bleeds through the cracks in the blinds, the heat kissing her skin and leaving her sighing contentedly into the pillow. She's almost positive she hears the pattering of feet on hardwood, but she just slides deeper into the blankets and lets herself fall back into a peaceful sleep. It's early, but upstairs must have company over.

Some time later, she wakes again, not to sunlight or the chirping of birds, but to a weight at her side, on her chest. Her eyes fly open, panicked and ready to reach for her gun, but she stops short when she's face to face with the source—sources—of the weight.

Two boys, twins, with shaggy brown hair and dressed in matching superhero pajamas.

"Mama!" the one at her side greets, and her eyes widen. He's not talking to her, obviously. The boy is undeterred by her lack of response as he maneuvers his small body and curls into her side.

The other one, straddling her waist, puts a pair of little hands on her cheeks and shoots her a wide grin. "Hi."

"Hi," she manages, eyes darting around the room while she tries to remain calm. Which is harder to do when she realizes this is not, in fact, her room. This is not her apartment, this is not her bed, and these are—well, she has no idea who these children are or why they're climbing on top of her. "Do you know where your parents are?"

She hears a mumbled "mama" from her side where twin number one seems to be falling asleep.

"Yes," she nods, keeping a soft smile on her face for them. "Where is your mama?"

"You're funny, mama," the boy on her chest laughs.

Sucking in a deep breath, she holds it for a few seconds before slowly blowing it out. Her heart is beating out of her chest, racing, and she continues this cycle until she manages to get it somewhat under control again. She has to figure out what's going on, but before she has a chance to come up with a plan to disentangle herself from the twins and start investigating, she hears more feet, followed by another voice.

A little girl with short brown hair, donned in a light pink pajama set with Hello Kitty on the front, wanders into the room.

"Morning, Mommy," she says, coming up to her side and throwing her arms around her shoulders.

What is happening? Mama? Mommy? She's fairly certain she's no one's mother. Surely she'd remember that. How many glasses of wine did she have last night? She'd needed a drink after their case, after the non-hickeys on both her and Castle's necks caused quite the commotion in the bullpen. One? Two maybe? Three tops. This must be a dream.

Yeah, that's it, a dream.

She closes her eyes, screws them together tightly and counts to ten before opening them again. Only she's not met with her bedroom, as she'd hoped she would be, but with the furrowed brows and cocked head of the young girl.

"There everyone is." A deep voice is added to the mix as a man enters the room, and she lifts her head, gaze landing on—no. No, it can't be. That's not... Castle? "I told you monsters to wake up mommy, not turn her into a jungle gym," he laughs, tugging the girl into his side, and Beckett barely has time to register what's going on before the boys scramble from the bed, one of them almost tripping when his feet get caught in the blankets.

"Daddy!"

"Woke mama!"

Eyes finally focusing, she looks up at the scene in front of her, both twins now attached to Castle's body, one at his hip and the other clutching at his leg. All she can do is stare, wide eyed, mouth hanging open in shock.

And now he's looking at her, confusion and concern etched into his features, and she doesn't know what to do. Shooting him for intruding in her bedroom comes to mind, but this isn't her bedroom and she doesn't have her gun.

"Kate?" Kate? Since when does he call her Kate? "Everything okay?"

Is everything okay? Is everything okay? She has no idea what's going on or where she is—well, okay, deduction would lead her to the conclusion that she's at Castle's, though there's no clear answer as to why—, she just woke up to three kids calling her mama, and she's lying in bed with him standing at the foot of it in nothing but boxers and a white t-shirt and—is that a ring on his finger?

Her eyes fall to the hand resting comfortably on the little girl's shoulder, to the fourth finger from the right, and yup, there's a wedding band. He's married? To who? Wait. She looks hastily down to her own hand and her stomach lodges itself in her throat. A matching wedding ring has somehow slipped itself onto her ring finger.

She is not married, and most definitely not married to Castle. This just solidifies it; this is a scarily realistic, very weird dream, and any second now she'll wake up.

"Lil, I need to talk to mommy for a minute. Bring your brothers into the living room, please," he says, taking his eyes off of her for a brief second.

"Is mommy okay?" The little girl, Lily, maybe, given the nickname, turns to her, big, concern-filled hazel eyes trained on her. She barely contains the gasp at the resemblance she's just noticing. "Are you okay, mommy?"

She looks just like... well, her. The hair, the eyes. She looks like her mini me, both as a child and back when Castle first started shadowing her. It's too much.

All she can do is muster up a nod, a small smile for the girl, and then Castle's stepping in, kneeling down until he's her height. "She's just fine, bug," he promises, hands on her shoulders. "Now, do me a favor and go take out ingredients for breakfast, okay?"

"What's for breakfast?"

"Whatever you want," he winks.

Lily gives a decisive nod, a bright smile on her face. "Okay. Come on Jake, Reece, let's go."

She watches him watch the three of them scamper off, Lily following the twins as they run as fast as their little legs will carry them. The grin on his face is one she's only ever seen when he's watching Alexis, and her heart clenches.

When he finally turns, he looks her up and down. "Hey, are you feeling alright?"

He's at her side in an instant, sitting at the edge of the bed with one hand on her leg. His eyes are clear, bright and even more blue than she remembers, questions and concern building.

Her eyes fall to the hand on her blanket clad knee, and she fights the temptation to wriggle away, run out the door and to her apartment until she finds out what the hell is going on. But something keeps her there, beside him.

"I'm—I don't know," she says then, raking a hand down her face.

He inches impossibly closer, and this time she does back away, but she doesn't miss the spark of hurt that flashes across his face. "What's wrong? Does something hurt?"

There's clattering of kitchen utensils hitting the floor, pots and pans colliding with each other, and then a brief pause followed by a reassuring, "everything's fine!" from Lily.

She scoffs. "Yeah, my head," she huffs. Too much. "Why am I here, Castle? Who are those kids? Why is there a wedding ring on my finger and why does it look suspiciously similar to yours?"

Castle's face scrunches up. "Kate, you're scaring me." She's scaring him? "Did you hit your head? You went out into the field with the boys again the other day, maybe you—"

Beckett shakes her head. "I'm always out in the field, Castle, or have you forgotten? That's kind of my job."

"I'll... come back to the job comment, okay, but Kate, are you telling me you don't know who our children are?" Our children. She doesn't have children. Castle has a child, yes, but she and Castle do not have children together. "Kate."

"No, no, you know what, you're right, I must have hit my head," she reasons, sitting up straighter. "This is all just a hallucination from a concussion."

There's a long, heavy silence that follows. Castle stares at her and she stares at anything but him.

"Staring's creepy, Castle," she mutters.

She hears him gasp a few minutes later and looks up to find his eyes wide, mouth open, a glee on his face that she doesn't understand. Maybe he's lost it, too. Seems to be a trend.

"Beckett."

He says her name like he's discovered something, like this is brand new information, a revelation. Is this some kind of game?

She looks around, then back to him. "What?"

"I just..." Castle says nothing else, just holds up a finger and leans in. She instinctively leans away, but she's stopped from going too far by the headboard. His hand reaches behind her and tugs at the hair tie, letting her hair fall over her shoulders. "Yes!"

Her eyes narrow, a look of pure confusion on her face. "What are you—"

"What's today?"

"What?"

He shakes his head, pushes on. "What year is it?"

"2010," she says slowly. "Are you okay?"

His face lights up, various emotions popping up, then disappearing as fast as they appear.

"I knew it," he breathes. "I can't believe it. This is so cool! Do you know how this happened? How you got here? Beckett, what's the last—"

"Castle," she hisses. "Since you clearly know what's going on here, care to enlighten me?"

"Time travel, my dear detective."

She rolls her eyes. "This is not the time for one of your wild conspiracy theories."

"You're here, in my loft, with no recollection of our life together, our marriage, our children. I'd say this is precisely the time for one of my theories," he retorts, and okay, if he doesn't stop saying our children she'll smack that smile right off his face.

She doesn't want to believe it, can't bring herself to believe it, but that little girl… she's the mirror image of herself. And those boys, those twins, they're all Castle with her eyes.

"Fine," she grumbles, waving a hand for him to talk.

"Your hair, it's shorter, straighter. But besides that, you think it's 2010, and since you haven't had any head injuries lately... You time traveled." She's almost worried the grin is going to split his face, and even more worried that she finds it adorable. "It's 2023." Her mouth opens. "I know."

"It's... 2023." He nods. "Okay. Alright. This could still be a dream."

He huffs. "Does it feel like a dream?"

"No," she murmurs begrudgingly. "But that doesn't mean—"

His lips are slanted over hers before she even finishes her sentence, his mouth quieting the gasp that escapes from her throat. It's quick, soft, and he's grinning when he pulls away. "Did that feel like a dream?" She shakes her head. "Good. Because I know your aversion to all things paranormal, but this is not a dream."

She bends over, stretching until her forehead is resting on her thighs, eyes closed. "I don't understand," she mumbles against the sheets.

Castle chuckles, a hand on her back. "Doesn't matter how it happened... or, it does, because I need to know how to make it work of course, but that's besides the point for right now. You're here, somehow, for some reason."

"Apparently," she grumbles.

"So, if you're here, does this mean my Kate is back in 2010?"

Beckett just shrugs, ignoring the my Kate part of his statement. One problem at a time. "Didn't exactly get an instruction manual, Castle."

"No, I suppose not. What—"

He's cut off when one of the boys runs into the room. She has no idea which one it is and there's a knot in her chest, a sensation she can't quite comprehend but feels oddly like guilt. If what Castle's saying is true, and to be honest, she has no better theories right now, then this little boy... he's his. Hers. Theirs.

"Daddy!" he yells as he collides into Castle's legs. "Jake made a mess."

Okay, so this is Reece. Jake and Reece. She likes it.

"What kind of mess?"

"Flour," Reece says confidently. "Lily cleaning."

"Lily's cleaning?"

The boy nods, floppy hair falling into his face. "Okay, bud. I'll be right out, go help your sister," he says, patting Reece on the back before he takes off again.

"So," she says, finally giving into what he's saying, "twins."

Castle lets out a laugh. "Twins," he confirms with a nod. "Didn't expect that, did you?"

One brow arches. "Does it look like I expected any of this?" She pauses, taking a breath. "Okay. Tell me."

"Tell you what?"

"About," she starts, waving a hand around, "this."

"I don't think I should be telling you anything," he says in response. "You're not supposed to know anything, really. It'll mess with the timeline, Beckett. You could change the way things are."

"That's if you go into the past. I'm in the future, it's already happened, I can't change anything." Beckett pauses, shaking her head. "I can't believe I just said that," she adds on a whispered mumble.

"Ah, but you can go back and change things to make sure that none of this happens," he counters, and she notes the sadness in his tone, the hidden fear that she will actually go back, however she gets there, and take steps to make sure they don't get married, that none of this becomes a reality.

She just rolls her eyes. "I won't." He doesn't know that, and she doesn't know that either, if she's being honest with herself. "Just tell me."

He sighs. "Fine," he relents, sitting back down. "But no specific dates."

She nods her agreement, motions for him to go on.

"We're married. The wedding was beautiful and everything we could've asked for. You're a senator. We live here, in the loft. We had it redone after…" His voice trails off, and she gives him a questioning look, but he shakes his head. "We had it redone. We have three children, as you've seen. Lily, who's seven, and Jake and Reece, who are three."

Beckett blows out a breath, taking it all in. "That's... okay."

Three kids. Three. Twins.

Wait. "Wait. Senator?"

"I am telling you nothing." His eyes glitter with amusement. "But yes. Senator Beckett," he confirms, and she doesn't miss the pure admiration in his voice.

"Wow."

She has so many questions, questions she's not even sure she wants to know the answers to, questions she's not sure she's ready to hear the answers to. But before she has a chance to even think about asking, finding a way to convince him to spill despite his assertions that she'll change the timeline, there's another yell from the kitchen.

Castle's off the bed in an instant, but then he turns back. "You coming?"

Her eyes widen. "I... give me a minute?"

He nods, and then turns and heads out the door, through the office and towards the noise.

Breathe, Beckett. Just breathe.

One leg and then the other. It's called walking, super easy once it gets going. After a few seconds of mental preparation, she forces herself to follow Castle's trail, and the sounds of little voices gets louder, clearer.

"Where's mama?" she hears, and as soon as she walks through the threshold there's a three year old running towards her. He slips a few feet in front of her, landing harshly on his knees, and then he looks up at her with a trembling lip.

She moves, doing the only thing she can think to do, and picks him up, cradling him to her chest as he whimpers. She can't tell them apart. His tiny fists clench in the fabric of her shirt, his head settled in the crook of her neck, and she bounces side to side. Her eyes find Castle's, panicked, completely out of her area of expertise, but he just signals for her to breathe and gives a reassuring nod.

"Reece, you okay?" he soothes, coming up beside her and running a hand down the boy's back. There's a small nod against her shoulder. "Gotta be careful, bud."

Reece settles against her, his arms still wrapped around her neck but his face oriented towards his father, a smile on his face as he sniffles. She continues to bounce with him, rubbing at his back, and Castle gives her a look while he goes back to the mess the boy made in the kitchen.

Moving around the island, she notices Lily on her knees, trying to scoop up all of the flour into her hands to put into a container.

"I'm sorry, daddy, I tried to grab a mixing bowl and Jake knocked over the flour—"

Castle puts his hands on her arm to stall her movements. "You did good, Lil," he assures her, pressing a kiss to her forehead. "I'll take it from here, you go get dressed, okay?" He leans in closer, lowering his voice to a conspiratorial whisper. "Gonna go have fun."

"Where are we going?"

"Surprise, bug," he teases, nudging her away from the mess. Lily looks over to Beckett, then back to him, but he beats her before she can ask. "Mommy's coming. No work today."

The girl's eyes light up as she nods, and then she's taking off towards the stairs. Reece wriggles from Beckett's grasp and joins his brother in the living room, bumped knee completely forgotten as he jumps onto the couch cushions littering the floor.

"Castle, what are you doing?" she whispers, eyes cutting from the boys back to him. "I can't go out. We need to figure out how to fix this."

He nods. "And we will. But I promised our children a day out," he tells her, and she lets out a sigh. "The Kate they know as their mother is presumably stuck in 2010, and you're here. Not much we can do about that right this moment, so you'll have to just… go along with it, Beckett. Get to know your kids a little early?" At the panicked, deer-in-headlights expression no doubt painted onto her face, he continues with a small laugh. "I know it's a lot. Three kids, husband, me of all people. I know where we were in 2010, I get it, but things have changed since then."

"Clearly."

"Just don't freak out, okay? Maybe you'll even enjoy it," he muses, nudging her with his elbow.

And then he's gone, disappeared back through his office, and she leans her elbows on the island. Without the support, she's positive she'd be on the floor. Her fingers rub at her temples, her eyes closed tightly, as she tries to just take a deep breath.

A day out. With Castle and his—their—kids. She has no choice, really, because these kids think she's their mother. But she's not. Not yet. These are her children, yeah, technically, but not hers. What is she thinking? What is Castle thinking? She can't do this.

Her breathing speeds up, renewed panic finding purchase around her ribs, when she feels a hand on her arm.

"Here," Castle says, handing her a pile of clothes. "Put these on, and breathe. It's okay."

"I'm not a baby person," she blurts out. "I can't do this. I don't know how to do this."

"Hey, hey, it's okay," he repeats, his hand rubbing in circles. "That's exactly what you told me when you found out you were pregnant with Lily." Her cheeks tinge pink at the intimacy of the conversation. "You'd get into these ruts and tell me you couldn't do it, that you were scared, that you had no idea what you were doing. But you did it, Beckett. Not for years for you, of course, but you did it, you'll do it, and you can do it now."

Breathing in, she holds it for a few seconds before blowing it out. "Okay. Yeah," she relents, grabbing the clothes from his hands. "Thank you."

"I'll get the rugrats, you get changed. Take a minute." He pauses, tugs her into a hug, and her body stiffens for a few seconds before relaxing. They don't do this. Not yet, at least, she reminds herself. "We'll get you back to the era of pretending to hate me in no time," he winks when he pulls back.

She disappears into the bedroom and tries to ignore the sounds of Castle making dinosaur noises with the twins.