I haven't written Castle fanfic since I was a kid but the finale's gotten me all nostalgic. I don't know if I'm happy or not with the way the show chose to close off the final episode but I felt compelled to write this version out anyways. Let me know what you think! I might write out a happier fill-in to the ending if I feel like starting a bigger project in the next couple of days. Obviously spoilers for the series finale, 8x22 'Crossfire'.

Warning: Major Character Death: This is the sad ending, don't read it if you don't want to.

A Variation on Transposition

"Hey Beckett?" His voice calls through the open space of the loft and into the bedroom where she sits, tugging her boots off at the end of the bed.

"Yeah?" She calls back because she can't quite will herself to get up yet. Too many hours of running on adrenalin and fear that have now started to sink away leave her limbs heavy.

"If Mason had an incinerator in the basement why wouldn't he just dispose of Caleb's body there?"

His voice cuts off somewhat abruptly and it makes her look up from her shoes.

"Castle?" There's another voice spilling through the loft now, not as loudly as Castle's was a moment ago and not loudly enough for her to make out the words. She gets up off the bed and steps out into the living room, her hand already at her waist, reaching for her gun.

"-without you and the missus hunting me."

"Castle!"

A volley of shots ring through the loft, first hers at Caleb then his back then hers again. There's a moment where she thinks that's the end of it, that she's hit him, before he returns another bullet and she matches it with one of her own. Then his body does slump down to the floor against the wall of the kitchen, his life already draining. He looks at her like he can't quite believe that she actually shot him then she disregards his presence in their home entirely.

Castle.

Her body seems to slip to the floor without her minds permission or realization and before she can discern the pain or the cause of it she's looking at the underside of their kitchen cabinets. She looks up, sees Castle across the kitchen floor, also on the ground, struggling to slide over towards her and she forces herself to roll over, moving closer to him as well. Her lungs feel as if the air has been ripped from them and the pain that she should have felt upon the initial impact of the bullet blooms forward, delayed at first but now suddenly, as it always does. She groans, just softly, when she reaches him and his hand stretches out towards hers. The contact of his skin against hers as he grips at her hand with not enough strength eases something inside of her that isn't the pain.

Their fingers twine together and she listens to his breathing for a moment. It's heavy and coarse, just slightly out of sync with her own gasps and she knows that however comforting it is at the moment, it's not a good sound. She can't quite think beyond that though, the pain overwhelms her mind along with the feeling of her shirt soaking through with blood. It sticks to her skin, tacky.

"Kate." He gasps and she wants to tell him not to talk but she can't.

"Castle." She'd like to tell him that she loves him, but getting out the second syllable of his name was enough work that she knows she'd never make it through a sentence. His head falls to the side to look at her and she stretches her neck up so that their eyes meet and she thinks that he hears it anyways. She hears it even though the words don't actually pass through his lips.

Then the air empties somewhat and it takes her a moment to place what has happened. His stuttering gasps have fallen to a halt and it is only her own left meeting her ears. Her heart cracks in her chest, knowing for the second time today that he's gone and won't be coming back brings a new ache forward that almost overwhelms the one though her stomach. But this time there won't be the relief of seeing him walk through the door, gun at the ready to save her. She wants to cry, or maybe scream, but there's no strength left in her to do either.

Her fingers squeeze his as her breaths get harder to pull in. They're not cold yet, his hands, they actually seem almost warm against hers, as they usually do. Maybe it's from the blood loss that her skin has already dropped in temperature as well but she can't really feel it. Her eyes close of their own regard but she doesn't try to fight it. The pain is already slipping away. She knows that soon her consciousness will go with it.

In the blackness, she thinks back across their lives. Her heart rate slowing numbs out the pain further and she can see it all so clearly. The first day they met, the first case they closed together. What was it that she said to him all those years ago? He had no idea how great they could be. She must have been lying at the time, there's no way that she could have imagined how great it is to be loved by Richard Castle. Their wedding, the almost one then the actual one, float through her mind, as does his proposal and the first time she ate dinner with his family and that first night he kissed her against the loft's front door.

She wonders how far they could have gotten before something caught up with them if she'd just walked away in the beginning like he'd asked. Would they have made it to their ten-year anniversary? Their twenty? Would she have stayed Captain of the Twelfth until she retired or moved on to something else? How many more books would he have written, stories that are still locked away somewhere inside of him? Or would they have moved on? Had a couple of children, maybe left the city for a little while. Alexis hadn't been subtle the last few years about wanting a little sister. So a girl first, one that Rick would tell stories to on the living room floor under a pile of blankets and that they would take out to the Hamptons to show the stars. Then maybe a couple of boys, ones with his bright mischievous eyes who held the same smile that she just can't quite say no to. They'd run around the loft at all hours, making up their own adventures and battles.

Her breathing lingers, each breath seeming just a little farther away from the last until she can't reach them anymore. She can hear the laughter through the loft that she will now never see inhabit it. Her eyes water for a moment until her grasp on her physical presence in the world slips and she gets lost. Lost in the beautiful potential of how much love their lives could have been.