A/N: Set midseason 4, before 4x19 (47 Seconds)

"In my end,

You were my beginning"

-Glass Heart Hymn by Paper Routes

She had told him to stay home that day. Not because she didn't want him there – she hopes he knows that – but because the weather had been bad. She almost laughs at the irony of it now. The weather of all things had kept them apart.

The day it all began, it had been dark and stormy, the cold wet and biting, and she didn't want to be at work herself. They hadn't caught a case and she was stuck sitting at her desk doing paperwork anyway, so she had called him at eight that morning and told him to stay home. He had argued, as expected, but after arriving at the agreement that she would come over later for dinner, maybe even crash in the guest room if the weather got worse, he had dramatically sighed his acceptance to remain in the safety of his loft and promised her a hot meal to look forward to. She still wishes she could have shared that meal with him before all hell had broken loose.

She had come close. It was nearing five in the afternoon when the outbreak hit the streets. Kate had been straightening up her desk, practically counting the minutes until she would be free, when a wave of panic had rolled through the homicide floor. At first it was just a few rookie officers getting jittery over the reports playing across the news. Talk of zombie-like cannibals roaming the streets, the numbers – the death toll – rising by the hour. When Esposito had come up to her desk with Ryan looking apprehensive and fidgety beside him and asked what she thought of the newscast, she had shrugged it off.

"A zombie apocalypse?" she had scoffed. "C'mon, guys."

Minutes later, she had begun to take it more seriously as the soundtrack of screaming filled the streets. She could still remember the heavy pounding of her heart and the fierce pump of adrenaline that had her hands shaking as she and the boys watched the chaos unfold from the precinct's third story window, a mantra of this can't be happening this can't be happening this can't be happening playing on a loop in her head.

"We've got to move," Esposito had said suddenly, jerking her out of her reverie. "We're live bait sitting in here."

"Yeah, I've seen enough episodes of The Walking Dead to know that if enough of those things band together they'll be strong enough to break through the lobby doors," Ryan had added anxiously.

"But how?" Kate had murmured, turning away from the window, the scene playing out below too gruesome for her to take any longer. "We're in the middle of it."

"We'll fight our way out," Esposito replied, blazing with determination as always, but his eyes had been dark. He had known their chances would be slim.

Ryan had nodded, always so hopeful, even in the end. "We've got to get to a rural area. The city will go down in hours at this rate and then it'll really be impossible to escape."

The boys had simultaneously headed to their desks, retrieving cellphones and scavenging through the drawers for extra clips of bullets. Kate had opened her mouth to speak, but her phone vibrating insistently in her coat pocket had interrupted.

"Castle?" she'd choked out without even checking the caller ID.

"Beckett?" he'd breathed her name with such relief. "Kate, oh thank god you're okay-"

"Castle, listen to me, you have to go, get out of the city. This - this thing, this epidemic, is only going to spread and the farther away you are, the better your chances."

"No," he had answered, his tone immediately shifting to that stubborn loyalty he had always held for her. "No, not without you."

"Please, Rick," she'd whispered into the phone, screwing her eyes shut so tightly white spots had started to form behind the lids. She had known the likelihood of her survival, she had known she was currently smack dab in the middle of one of the world's largest cities while an actual zombie apocalypse was happening outside, and she had known he was closer to a way out than she was. "It's too late for me. Go to the Hamptons, stay there for as long as you can. I'll - maybe I'll be able to try and meet you there at some point."

"Where are you, Kate? I'll come get you, I'll-"

Their connection had started to fade, the line crackling, but she remembers the sound of him trying to persuade her, trying to convince her that they would make it out of this together.

"I love you, Castle," she had murmured, needing him to hear it if those were to be the final words she spoke to him. "I love you so much." And then she had ended the call.

Castle had always raved about the zombie apocalypse, spoke of it as if it would be some compelling adventure. It wasn't.

He calls her again and again after she utters those final words, words he had always been longing to hear from her, but not like this. God, not like this. Eventually, the phone lines go down permanently and all he can hear is the echo of a dial tone every time he tries to reach her.

Castle knew without a doubt what was happening the moment it was reported on the news, and his first instinct had been to protect his family, including one member who was currently across town. He had watched all the films, read all the books - he knew the city would be a bloodbath in no time and that they needed to evacuate, but he couldn't leave without Beckett. That wasn't even an option.

But he wouldn't make his family stay either.

"I want you to go to the Hamptons, I want you to stay there," he announces to both his mother and daughter after finally giving up on contacting Kate again.

Despite the hysteria overtaking their lives, Martha remains calm, cool and collected through the beginning of the outbreak. Alexis, on the other hand, panics, clutching his arm and not letting neither he nor Martha out of her sight even though the three of them are locked together in the loft already.

"Come too," his mother begs softly, stroking his cheek with a glittering layer of moisture gathering in her vibrant blue eyes, eyes filled with knowledge. She already knows what he intends to do.

He covers her hand with his, squeezes lightly.

"When I can."

"Dad, no. Please don't tell me you're staying here. Please, you can't-"

Castle gently urges her to relinquish the death grip she has on his shoulder and then he hugs her tightly, burying his face in her fiery red hair.

"I love you, Pumpkin. Please try to understand."

She releases a sob into his chest that shatters his heart into a million sharp, jagged pieces. As a father, it went against every fiber of his being to send his daughter off without him, but he was sending her to what he hopes is safety.

"Alexis darling," Martha cuts in soft but firm, patting her granddaughter's back. "Go pack a bag. Hurry, we don't have a lot of time."

Alexis pulls away from him, wiping at her eyes and glancing to him helplessly before turning away and bounding up the stairs.

"You'll take care of her?" he questions solemnly, voice cracking along the words.

"You know I will. I'll get us both to the Hamptons and we'll be waiting for you," she promises him, but they both know her words hold little truth. "Richard, I know you care about Katherine, but she's-"

"Don't," he mutters through gritted teeth.

"She is as good as dead," she finishes somberly, but with desperation, unwilling to leave him alone in a city of corpses. "If not now then-"

"I won't just abandon her. If anything happens to her…" He lets the sentence trail and shakes his head adamantly. "No, I can't leave until I know."

He hugs them both for too long, kisses their foreheads, and then sends his mother and daughter out the back entryway with Eduardo, the doorkeeper who had managed to keep the walking dead out of their building. At least they have someone he knows can protect them, or at least get them safely to the waiting vehicle parked outside.

Castle forces himself not to watch as they drive away, returning to his bedroom instead, rummaging through all of his belongings, making sure he has all the vital necessities he would need. He won't leave until tomorrow, the outbreak is too great right now in its infant stage. He knows it will not have improved much by morning, but the absolute worst will likely be over, and he hopes Kate knows that too, hopes she's smart enough to stay safe inside the precinct or anywhere that offers her protection from the walkers.

He hopes she knows how much he loves her back.

Kate, Ryan, and Esposito make it out of the precinct alive, but the parking garage is barricaded with bodies, and none of them are feeling lucky enough to sneak past and attempt a car jacking.

"We need to find a place to hole up," Esposito whispers. They're huddled in an alley, trying to make a plan while they actually have the chance.

"We need supplies too," she decides. "Aside from food and water, we need basic tools and necessities."

"The stores are deathtraps," Ryan states, and it's true.

Practically every building is crawling with corpses, but especially the places of food, water, and artillery – too many desperate survivors with the same goal all meeting the same fate. Esposito had raided the armory in the precinct before they made their escape, and divided the weapons among the three of them evenly. Currently, weapons are at the bottom of their shopping list.

"My apartment is closest, we'll stop there first," she murmurs, doing the geography in her head. "Kevin's next, then yours, Espo."

The three of them nod, check their guns, and head into the chaos.

It doesn't surprise her that every apartment in the building has been broken into, including her own, but anything worthy of stealing is hidden away and her place is practically untouched. She heads straight for her bedroom while the boys raid her kitchen, throwing any perishables inside a plastic bag. She has no time to linger, her home is definitely not a safe place for them to stay, and she hastily grabs an armful of clothes, enough to last her for a couple of days, retrieves her backup piece from the top drawer of her nightstand, but just before she exits the room, she impulsively stops at her bureau, snags two picture frames and breaks them both against the wooden corner of the dresser.

"Beckett, you okay?" Esposito calls and she returns a noncommittal assurance while she pries the photos from their display cases.

She folds the photo of herself and her mother from that day at the ice skating rink into the inside of her coat pocket, does the same with the next picture of herself and Castle.

It was stupid, she still couldn't believe she had framed it, but the silly photo Ryan had snapped of the two of them grinning at one another in the dim lighting of the Old Haunt had always been a favorite of hers. She wasn't going to give it up now.

"Ready?" she asks, coming out of the bedroom with her bag slung over her shoulder.

The second day of the zombie apocalypse – he was sincerely shocked when he woke up that morning after only two hours of sleep to realize it all wasn't a dream – is no better than the first he realizes with chagrin, but he can't stay home any longer, not when she's still out there. The precinct isn't exactly close, but it's not too far either and he has faith in his knowledge of the living dead, that he can sneak past them and make it to Beckett unscathed.

If he didn't locate her at the precinct, he would give in and acquire one of the many abandoned vehicles parked along the streets and drive until he made it to his family.

They lose Ryan on the third day.

Working through the city to get to each of their apartments is harder than she could have ever imagined. There have been too many close calls to count, but Esposito has become the most skilled at silently taking down the soulless attackers with whatever weapon he has handy, and as long as they keep quiet and avoid the large groups that had curiously congregated around Times Square, they can usually make their way past without much trouble.

They are only a few blocks from Ryan's apartment when an unexpected horde comes down on them, sending the three scrambling into an alley, trapped. One of the buildings has a door though, an abandoned pawnshop, and Esposito has it cracked open with a single thrust of his shoulder. Both he and Kate make it inside and are holding the door for Ryan, but he isn't following.

"Kevin!" Esposito shouts, but his partner is frozen, and that's when Kate sees it. Her.

Jenny coming towards him, eyes dead but hungry, and Ryan couldn't seem to look away.

Kate digs her knife into the skulls of the two loitering walkers they find inside the pawnshop. Esposito barely notices, remains slumped against the door with a look of horror she's never seen on his face. She doesn't know where Lanie is, whether she's dead or alive, but maybe it was better, the not knowing.

Evening was descending and she had noticed the night before that the walkers tend to be more active in the darkness, so she decides the two of them will remain inside the shop for the night. The glass door in the front has bars drawn and secured, so she focuses on barricading the back entrance they came through, finds food in the shop's main office and forces a cold can of soup into Esposito's shaking hands an hour later. He doesn't say anything, only mindlessly sips at the broth.

The next morning, she searches the store thoroughly for anything that might be useful to them, lingers curiously on a sheathed sword behind the front desk. She draws the gleaming katana free, tests the weight of it in her hand. She likes the feel of the new weapon, learns hours later that she's quite talented with it as well, leaving even Esposito a little slack jawed when he witnesses her behead walker after walker as they scour the streets for shelter.

"Where are we going, Beckett?" he asks when the sun is high in the sky and they're still outside.

Kate doesn't answer. She knows where she's going and she silently curses Castle for living in one of the most difficult buildings to access in town. But she has to know he made it out, has to be sure he isn't still in the god forsaken city of New York.

Castle's old building in SoHo is overflowing with corpses. By the time they make it to his loft, she's slick with blood and cradling her tired arm to her side. His loft is surprisingly still locked, but she knows where he keeps the extra key and takes a breath of preparation before slipping inside with Esposito flanking her.

The place is clear, dark and empty. She doesn't know whether her sigh is of relief or disappointment.

Coming to the conclusion that Castle's loft is the safest place they're going to find, they settle in for the night – Esposito taking the upstairs bedroom while she slinks into Castle's old office, chuckling softly as her eyes catch sight of the assortment of zombie survival guides strewn across his desk. In his bedroom, clothes are scattered on the bed, picture frames and trinkets are knocked over, and his bathroom is in a state of obvious disarray. All evident signs of someone who left in a hurry and she takes it as confirmation that he has heeded her advice, that he made it out of the city in time and to the Hamptons where he would be safe.

For the millionth time in 96 hours, she wishes she had been with him when the world went to shit. She wishes she had ignored the stupid wall around her heart and told him she loved him sooner, not over the phone because she knew it was the end.

She ends up crying quietly in his closet, surrounded by the scent of his cologne.

Castle ends up in Remy's that night – irony, he thinks – and although the diner isn't necessarily safe, it's currently one of the only buildings in existence that's actually empty. He barricades himself inside, stacking tables and chairs against the glass front entrance and hiding out behind the swinging doors of the kitchen.

The gas stove still works and he manages to cook himself a burger with meat that thankfully has another few days before it hits expiration. It doesn't taste as good though, not like the ones he's shared in this same diner with her in the past. Nothing will ever be as good as it was in the past.

He's dozing against the kitchen wall when he feels the building shake. At first, he fears it's walkers at the door, a herd of them attempting to break through the glass, but then the diner shakes again and he realizes it's the earth shuddering.

He pokes his head out of the kitchen to take a risky glance through the window, and that's when he sees the world is on fire.

They'd had no idea what kind of action the government would take, if there was still a government at all, but when helicopters fill the air and fire lights the night sky, they figure the plan is apparently to wipe the major cities clean of the infected by performing a mass exodus. Or at least trying to.

Beckett and Esposito make a hasty exit from the loft, the building too vulnerable under the city's state of distress. They quickly decide to head back to the precinct, nowhere else left to go, but through the mayhem of bombs and darkness and living dead roaming the streets, she and Javi quickly become separated and neither even have the chance to say goodbye before they're swept in different directions.

The blinding rain of the thunderstorm that bears down on Manhattan that same night aids in extinguishing the multitude of fires and confusing the walkers. She should be thankful for the assistance the weather gives her in making it to the Twelfth precinct safely. She should be thankful the Twelfth is still standing. But she doesn't feel grateful; she doesn't feel anything. She is alone.

Kate barricades herself in one of the conference rooms on the homicide floor for the night, shivering from the storm outside and the grief consuming her soul. Everyone she knew, everyone she had ever loved was probably dead and she is all alone in a world that has gone to hell.

She sighs, slumps into the corner and bunches up her jacket against the wall to use for a pillow. She doubts she'll sleep very long, if at all, but she's finally starting to drift off when she hears a sound in the bullpen.

"Shit," she whispers, blinking away the slumber and retrieving her sword from its resting place beside her. She wouldn't leave the room, not yet, she wanted to hear the threat first and make sure she knew what she was up against. Either one walker or a dozen, a single straggler in a city of many or a gang of them. She didn't even care, she would kill the intruder, living or dead.

But suddenly the handle to the conference room is rattling and Kate crouches in the corner, waits until the door creaks open to rise, her sword poised at the intruder's neck.

"Kate," the voice breathes and… oh god, it couldn't be real.

"Castle?" she whispers, skeptically lowering the blade and allowing him to lift the magnum flashlight at his side. It illuminates the room and shows her she isn't hallucinating. Richard Castle is alive and standing in the same room with her.

The katana clatters to the ground as Kate crashes into him, swallowing back sobs as his arms wrap around her securely.

"You're alive," he gasps into her hair, the disbelief a heavy rasp in his voice and she pulls back in his embrace, stares up at him, sees the loss and weariness in his eyes. "I've been looking everywhere."

"You're supposed to be in the Hamptons, you're supposed to be safe," she says softly, guiltily, as she strokes her fingertips along his jaw. He was supposed to be safe.

"I couldn't leave without you," he murmurs, tracing his fingers over her cheek as if to memorize the feel of her skin. "I love you, I couldn't leave."

She kisses him, long and slow, their first real kiss. She drinks the raindrops from his lips, soothes her tongue along the roof of his mouth, and commits to memory the intoxicating taste of him.

"I love you too," she chokes, cradling his head in her hands, smoothing her thumbs over the hollows of his cheeks. "So much. God, Castle-"

He folds her into his chest as her body finally gives into the agony of this new world, of all its ugliness and unfathomable cruelties.

"Who have we lost?" he whispers, stroking his fingers through the mangled locks of her hair.

"Everyone," she rasps into his shirt, closing her eyes against the dried bloodstains scattered across the fabric. "Ryan, Espo, and I - we stuck together after the outbreak. We went to my place, tried to get to Ryan's next, but then he - and Jenny was-"

"Oh god," he whispers and she nods, blinking back the tears that just won't stop.

"Espo and I ended up at your place, but then the bombing… We got separated, I don't know where… if he's even…"

"If anyone can make it out there on his own, it's him," he tries to assure her, and it isn't necessarily a lie. Esposito has just as much a chance as they do.

"You were at the loft?" he asks suddenly.

"Earlier. I was sure you had gone when I saw your room," she murmurs senselessly and feels Castle's arms tighten around her.

"Dammit, I should have just stayed put. We could have been together sooner. We could have-"

"We're together now," she whispers, grazing her lips up the column of his throat, savoring the warmth of his skin.

"I'm with you," he promises her, serious as he takes one of her hands and holds it firmly between both of his. "Until the end."

"Partners for a reason," she whispers with a withering attempt at a smile, but he gives her a real smile back.

"I have - I have some food," she remembers suddenly, because god, he looks like he needs it far more than she does. "And one of your shirts if you want-"

"Stealing mementos from my loft, Beckett?" he grins and she feels the frown lines curved at the edges of her mouth cracking to accommodate the smile she feels grow for him.

"The backup generator is still running, which means the showers still work here," she murmurs, allowing her hands to drift down his sides, curl at his hips. "I was going to take one before morning, if you want to join me."

"I would like that."

The first time he makes love to her is in a shower stall in the locker room and it's the most beautiful thing she's experienced in a long time, even before the apocalypse.

"Where are we going?" she asks once they're both dry and dressed again.

"I'm sure we can find a vehicle right?"

Kate nods.

"To the Hamptons then. I sent Mother and Alexis in the beginning, I don't know if they made it, but regardless, it's our best option for fortification," he explains and she knows he's right, but getting out of the city will not be easy. Easy doesn't exist anymore.

"If something happens," she starts when they're in the lobby of the Twelfth, near the backdoor since the front is a deathtrap. "You go without me, Castle. Go and don't look back."

Rick shakes his head, cradles her face in his hands and gazes down at her intently.

"I don't go anywhere without you."

"Rick." His name crumbles on her tongue. "You have to promise me-"

"It isn't a promise I can keep, Kate."

She surges up on her toes, claims his mouth like it's the last time because it very well could be, and he gives it back just as desperately.

"We're going to make it," he pants, clutching her hand in his, gun in the other. "We have to."

They make it, just barely. A horde of walkers closes in on them while she's trying to hot wire the gassed up charger they came across and instead of wasting bullets and drawing even more attention to themselves with the noise, he fends each of them off with a baseball bat. But Castle quickly becomes outnumbered and just when she thinks it's going to be the end, the engine roars to life and he's sliding in the passenger seat as she peels out of the street.

"Okay?" she questions, reaching over to sweep her fingers over his arm, over the throbbing pulse of his neck.

He swallows unsteadily, the panic still fresh in his eyes, and nods.

"I'm good," he assures her, catching her hand and bringing her palm to his lips.

They spend their morning driving, taking as many shortcuts as they can to avoid the main roads, luckily encountering little congestion on the way out of the city and through the highways that lead to his home on the beach, only stopping once to raid a convenience store that looks relatively free of the undead.

"So you were the one who left the trail of the dead in the station," he surmises with a smirk as they're heading back to the car, nodding to the sword in her hand.

"Turns out I'm pretty good with blades," she quips, ridding the blood from the weapon with a quick flick of her wrist before depositing their meager haul of groceries into the backseat with the rest of their supplies and rations.

He's standing behind her when she shuts the backdoor, surprises her with the clutch of his hand around her nape and the crash of his mouth to hers, robbing her of breath with his tongue. "Even in the apocalypse, you still manage to be the hottest woman to exist," he breathes against her lips and she smiles.

"Kind of a nerdy fantasy come true for you, huh?"

"Little bit," he agrees, but his eyes darken and she realizes the darkness is normal now. The cerulean light in his irises will remain a rare gem reserved only for her. "As long as I have you."

Any other circumstance and she would have scoffed at him, at the corny remark, but the luxury of wasting words in subtext is gone and every sound that comes from his mouth must be savored, so she kisses him again instead, whispers always before they get back on the road.

The still operating gate of private the community his house is located in is a good sign, makes her tentatively hopeful that maybe it could be a little safer here. Safer than the city at least. Walkers shuffle across the roads, but she counts a handful at most, such a change from the overflown streets of Manhattan.

It's already midday when they finally see his house rising up in the distance and Kate holds her breath the entire slow climb up to his driveway. He exits the car to unlock the gate and she keeps her window open and her Glock in hand, but no threat appears and he slips back inside after she's driven the car through and he's resealed the gate behind them.

"Castle," she whispers, reaching for his fingers anxiously once they're parked in front of the mansion she doesn't even have the opportunity to be in awe over, too afraid of what they might find, what they might not. This place needed to be a safe haven, just for now. They need a place to survive because if she loses Castle too…

"Shh," he soothes, thumb racing back and forth over her cracked knuckles. "Whatever happens," he reminds her and she nods her agreement.

They step out of the car, weapons drawn, her katana slung across her back, and approach the house with caution. The front door is locked, dead bolted, by the feel of it, but Castle rummages around on the porch, pauses at an assortment of rotting potted plants. Kate watches him withdraw a key that unlocks the door for them with relative ease.

She slips inside first out of habit, scans the area with her gun leveled. She nods to him over her shoulder once she sees the front room is clear, but then they both hear a creak from the nearby stairs and freeze at the click of a gun's safety being turned off.

"Take another step and you lose your arm." A voice cold as ice warns them from the staircase and Kate's eyes widen.

"Alexis?" Castle calls back in surprise and the sharp intake of breath fills the room.

The young woman comes hesitantly down the stairs, a rifle in hand and a look of shock on her face. But she looks healthy, his daughter looks fine.

"Daddy?"

Castle locks the door behind them, tucks the key into his pocket just in time to catch Alexis when she flings herself into his arms.

"You're alive," she cries. "We were wondering for so long if-"

It's then that Alexis notices Kate in the shadows, and for a moment, Kate fears grudges from the past are about to ruin everything, but Alexis merely slips from her father's embrace into Kate's, hugging her just as tightly.

"I'm glad you're okay, I'm so glad you both made it," she whispers. "Let me go get Grams, she's upstairs organizing the artillery."

Alexis bounds up the stairs, leaving them alone in the foyer and Kate turns to him with her heart beating almost painfully fast.

"It's safe here," she breaths and Castle opens his arm to her, gently tugs her into his side.

"We're safe here," he confirms, dusting his lips over the dirty skin of her forehead.

"We're going to make it, Kate."

Beckett looks up at him, lays her hand along his cheek. She never thought she would be crying from happiness, not once through this hellish ordeal, but she is now.

She nods, kisses him just once before his mother and daughter join them.

"We're going to make it."