Author's Note: This started as a one shot that grew entirely too long so I've split it into three chapters that I'll post over this week. Huge thanks to both Nic and Jess for reading over this multiple times, helping me hopefully make it into something worthy of posting, and for being generally wonderful and encouraging.

Submersion - Part 1

This time it's different…

It's the sharp blow of impact, a jolt of force that jerks them forward, sends them flying. There's no time to brace themselves, no time to do anything but hold on for the hard collision with the water, the inevitable fall that follows. It's a seemingly endless descent as the daylight is swallowed by darkness, a muddied brown that forces its way in and around them. She claws helplessly at the seatbelt, squints through the fading light, eyes wide, desperate. It's only been seconds but it feels like the longest moment of her life. Her mind screams that this can't be the end. It can't be. No.

She writhes vigorously beneath the restraint, struggles to loosen it, tugs as hard as she can against the lock. But the water is rising rapidly, seeping in through every window, every door, every crack that it can invade. Relentless as it rips through the space, stealing their air. Precious air. Time is not on their side.

She turns to him, and for just a moment he holds her gaze. His eyes reflect the fear she feels, their usual spark of blue dulled by the darkness and he reaches out for her, mimics her attempts to tear the fabric of the seatbelt, pulls and wrestles with the lock over and over. But it doesn't budge.

Desolation washes over her with every inch of rising water. They speak in frantic tones, trying to find the knife or the gun, anything to get her out, but they can't, they've got nothing this time, and then there are no more words exchanged, no sounds except for the steady rush of the Hudson filling the cruiser and the rattle of her seat from their ongoing battle with the lock as they continue to sink deeper, so much deeper.

There's only a foot of space left between water and roof and she strains her neck, tries to savor every last gasp of oxygen. She can feel the panic rolling off of him in waves as they fight to free her. She can't understand why nothing is working. They got out last time, they got the gun, it's supposed to be under the seat, it's supposed to save them. But this time she's still pinned, effectively trapped, her fate sealed. Their eyes lock again as they both take one final, deep breath before they're completely submerged.

She can read the silent apology in his expression, the regret, the pain. All of the words they still haven't said, that they still need to say, will never have the chance to say now; the weight of everything left unspoken is heavy between them, suffocating, just like the water she's drowning in.

She knows he has to leave her. He only has a narrow window of time to make it to surface before the air in his lungs runs out; and all at once she realizes, it's not dying that scares her, it's losing him. She'll never know what it could have been like, would have been like to truly live with him by her side. She'll never hear his voice again, see the laughter in his eyes, feel the touch of his hand soft against her skin. The words she's kept hidden, treasured and feared for the last nine months - she'll never be able to say them back. He'll never know she felt...no, feels the same. It's not just water that turns her blood to ice in her veins.

She closes her eyes, grips his hand, squeezes it one last time, and prays that somehow he knows how much he means to her. Prays that he'll remember her, remember always and that maybe over time he'll forget all that she wasn't - all that she couldn't be for him. She motions for him to swim while he still can, while there is still enough air, and then she lets go…

This isn't worth both of their lives. He can still make it out. He can still live. He has to live.

But when she opens her eyes again he's still there. For some reason he's not swimming, he's not kicking his way through the window, he's reaching out for her, clinging to her. No, Castle, no.

It's not supposed to happen this way.

It's getting increasingly harder not to inhale. The pressure in her lungs is building, building and she keeps pushing him, punching at his shoulders as much as she can from where she's trapped. Please go, Castle. Please, please…you can't die too.

But it's no use. He shakes his head vehemently at her. No, Kate. I'm not leaving you here alone. He's managed to curl himself around her, pull her head to his shoulder, eerily similar to the way they clung together in that freezer a year ago. Was it only a year ago?

It's not so much unlike that night. How many times have they faced death together? The cold seeps into every pore of her body, absolutely everything aches. The silence is deafening now that they're underwater and the cruelest part is that she still can't say the words. I love you, Castle. I love you too.

She looks up into his eyes through the murky depths and makes the only decision she has left. She crashes her lips against his, shares her last breath with him. If this is how it's supposed to end – how it's going to end – she'll give him everything she has left.

Then, she finally succumbs to the need for air.

She wakes with a start, gasping at the remnants of the nightmare still flashing before her eyes. Her phone is ringing loud next to her on the nightstand and she reaches for it blindly. She tries her best to growl her last name into the speaker as her chest heaves and her heart pounds violently. She retrieves the pen and pad she keeps nearby for just this purpose and scribbles down the address quickly before hanging up and sinking back against the headboard of her bed, needing a moment to collect herself.

It's that awful nightmare again. She's had it every night since the case closed. It always starts the same but she can never predict how it will end. Sometimes they're both able to get free. Sometimes it's Castle who's stuck, other times it's her. Sometimes the last thing she sees is Sophia Turner's face taunting her, laughing, eyes coldly watching her drown. But tonight's…that one was new. And it's left her shaking, completely and utterly wrecked.

She finally shoves the covers off and pads across the floor to her bathroom on unsteady legs, flicking on the light, thankful to be surrounded by its warm glow. She's tempted to roll her eyes at herself for this new personal low. Since when has she ever been uneasy in the dark? The idea is ridiculous to her but she can't deny it. It's just a little too much right now, too reminiscent of drowning in that icey, shadowy water, of being just that close to giving in to the end.

Her face is pale but for the massive shadows underneath her eyes. She turns on the faucet, waits for it to heat, and splashes some water against her cheeks, hoping that she will regain some color. She stares at her reflection for a moment, takes another deep breath, and tries to suppress the shiver that runs through her body. She hasn't been warm in a week, not since before that night. Lanie diagnosed them both with mild hypothermia after their dip in the river but she knows it's more than that. This brand of cold runs much deeper.

They've cheated death so many times and she can't help but ask herself, how many chances are they going to get? How many days is she going to waste, not speaking, selfishly holding onto his words? What good are they if she's not willing to embrace them, recognize their meaning? She wants to be ready so badly that it hurts - it aches all the way down to her bones. She's so tired of doing this alone but it's all she's known for so long. And she doesn't trust herself not to ruin everything. She can't ruin this - the one good thing in her life, even as complicated as it is right now.

She sighs as she returns to her room and opens her dresser, reaches in and pulls out a pair of jeans, a button up, and her favorite Burberry coat. At least she'll get to see him today. Even if it's the coward's way out, work related and not anything like what she really wants, it still helps to have him nearby. It still eases some of the chill she's not been able to fully shake since last week. She'll call him in a few minutes, meet him at the scene, and they'll step back into their careful, cautious dance. A little less playful than it used to be but still the only comfort she seeks. The only constant in her life, keeping her afloat. And right now, she could really use a cup of coffee.

Unfortunately, her day does not improve.

The case is horrific. A carjacking that turned into a double homicide when the victims tried to resist. The bodies were disposed of in a particularly gruesome manner that even had Lanie grimacing at the scene.

Then, the boys nearly get jumped by a group of thugs who happened to be in the reportedly abandoned warehouse where the car was ditched.

As if that wasn't enough, Castle and she spend all day trying to track down leads across the city. Her current cruiser (a temporary replacement that appears to be about twenty years old) breaks down on them while they're on the way back to the precinct.

And after all that they finally make it back only to find that a witness came forward and had been waiting with an ID of the carjacker. One that essentially cracked the case for them and could have ended the investigation hours earlier if someone had just called to let her know.

By the end of the day she's exhausted and annoyed, the little sleep she'd gotten the night before not nearly enough. Yet, she finds herself dreading the thought of going home, crawling into bed alone, only to slip back into another nightmare. She doesn't think she can handle another night alone with those dreams. If she can just wait out most of the uniforms, she's made up her mind that she will crash in the break room. Not ideal but it's a plan that sounds way more appealing than her empty apartment.

So she's hunched over paperwork on her desk, fighting to keep her eyes open, just waiting for the precinct to clear out a bit, when she feels his hand on her shoulder.

"Beckett, let me take you home."

She wants so badly to lean back into his touch. She's so tired and his hand is so warm. It'd be so easy to give in to the comfort he offers, the magnetic pull of her body to his.

"Yo Ryan! Can you give me a hand with these files?"

She hears Esposito yell across the room and that's all it takes to jolt her out of her brief reverie. She stiffens on reflex. What was she thinking? She groans inwardly. She's got to be stronger than this.

She shakes her head, keeps her eyes set down, pretends to focus on the pages in front of her. "You go on, Castle, I'll leave soon." She could have sworn he left thirty minutes ago. She's not sure she's equipped to resist his pestering right now.

"Mmm, nope, sorry can't do that. I'm not leaving til you do," he says in that matter of fact voice, plopping down into his chair, leaning back exaggeratedly and lacing his fingers together across his chest.

It's his determined stance. The one that he loves to use against her. Mostly for the fact that she caves to it, oh, about ninety-nine percent of the time now. He knows that she knows he's got no qualms about calling her bluff. Stubborn man – he will sit there staring at her for hours until she finally gets so frustrated that she yields to him. He's proven it on more than few occasions.

"Besides Beckett, you don't have a ride, remember," he continues. "You kind of need me."

And, oh, if only he knew how closely those words hit home to her. She huffs at him, finally looks up, meets his eyes and his expression softens immediately. He leans forward and lays his hand on her arm. "Kate, seriously, let me take you home. You look like you haven't slept in days."

He must see the expression on her face because he backpedals immediately. "I mean, you look great, but you - well, you look so sleepy. And I know you're trying to hide it but I've seen you yawn at least five times…" he rambles on, chuckling nervously.

Maybe it's the exhaustion, maybe it's the way her heart is racing once again at his proximity, or maybe it's just that his words have always gotten to her, reached her in ways that no one else's can. But her defenses are all totally shot by this point and she finally finds herself cutting him off, agreeing, letting him hold her coat as she slips her arms into it, his hands lingering just a moment longer than necessary. And before she knows it, he's ushering her into the elevator, his hand warm against the small of her back. This time she does lean into his touch.

Thoughts?