It's friendly fire that gets him in the end.
The bullet kisses his collar bone before completing a biting, clawing voyage through unscarred flesh. The world around him splinters with it, and in a monochrome blur he finds himself on the floor with no recollection of his journey down. He doesn't care. He's not entirely sober, but it's been hours since his last dose back in the car (a few months ago he made a promise to himself to go into this fight clear-headed and sharp and ready for the end. Cas is good at breaking promises) and he could really do with a hit right now.
The savage howls of the Croats and the all-too-human cries of his comrades echo around him through a barrage of fire and emptying shells. The air tastes like death and you know what? Fuck this. It's not like the plan requires any of them to live anyway, so what's the point in standing up if he'll only be knocked back down again? Either Dean wins, or he doesn't. End of story, and knowing their luck it won't be a happy one. The concrete floor is cool against his cheek, and the screaming in his shoulder fades along with his sight and hearing.
The darkness beckons with open arms and, well, these days Cas is never one to deny himself the simple pleasures.
.
.
.
When Cas opens his eyes, he hopes he is dead. That dream is soon crushed, however, by the brute force that is the pain in his shoulder. For a moment he doesn't move, instead electing to count those cracks in the ceiling that are still visible under the faint orange light. A clump of dandelions has found its way through one fissure in the derelict floor above, which is nice. Blood oozes from another.
Sighing, he attempts to sit up (with much protest from his shattered collar bone and punctured flesh) and regrets it instantly. Not from the pain, but from the sight and the stench. There are corpses piled around him, and his back is sticky with both his own blood and that of the dead. The details have been obscured in the darkness, and for that he's glad, but the silence is terrifying. Body upon unmoving body lies untouched, even by the flies, and it feels to Cas as if an emptiness has swallowed the world.
He can't stay here. This he knows, so despite his agony and his fatigue he stands. His legs feel like toothpicks as he makes his way to a door (he doesn't know where it leads, and quite frankly he doesn't care. Hopefully wherever it goes there'll be fewer corpses), briefly pausing for breath before realising that inhaling through the nose probably isn't the best idea.
When he finally manages to place his hand on the door's splintered wood, it swings open to reveal a storage room with not a body in sight. What he sees instead makes him choke out a bitter laugh. Before him, relatively untouched by dust and grime lies pile upon neatly-stacked pile of soft, snow-white treasure. Fucking demons seem to have hoarded every roll of toilet paper in the tri-state area. If Cas hated demons before, this (of all things) is the final straw. They don't even need toilet paper. The bastards just felt the need to torture the poor remaining souls on this earth in every way possible.
Besides the obvious, the room is otherwise uninteresting. A broken window. A crumbling wall. It's night, but not a single star pierces the inky black of the sky outside. He vaguely wonders where the orange light is coming from, and walks to the window where he is mildly surprised to discover a single tree in the courtyard garden is all aflame.
He pretends he doesn't see Dean's broken body in among the roses.
Well, he tries.
Because of course he wasn't holding out for the hope that they might have won. That Lucifer might actually be dead, and he would be allowed to pick up the pieces of a broken world and an even more broken Dean, and it wouldn't be perfect and the act of killing his brother would weigh down on Dean like a tombstone on his back, but Cas would be there always and Dean would live, and they would grow old together and get a place by the sea where the wind would run its soothing fingers over their chapped and smiling lips.
Cas tells himself the only thing keeping him going all this time was not the thought that Dean might live.
It is a lie.
When Cas first fell, when he first felt the last remaining dregs of his Grace ripped from his very core leaving him vulnerably, pathetically human, he was ready to give up. He wanted to curl up then and there in the rain and the dark and the dirt and never get up again. But Dean came and sat down beside him, his head tilted towards the sky.
'Get up,' he said, in a voice painfully torn half way between Fearless Leader giving an absolute command, and Big Brother tucking Sammy in at night.
'Make me.'
'Oh trust me, I will. But it'd be better if you stood on your own.'
'What's the point? Every step I take reminds me that I'm not flying. And that not only is this mortality is killing me slowly, I probably won't even live out my short human lifetime. Lucifer is going to win, Dean. We're all going to die! All of us! We'll all burn!" He was in hysterics now, half way between laughing and crying, and didn't seem to know how to stop.
Dean calmly reached forward placing one hand on Cas' shoulder, and grabbed his chin with the other to turn his face towards him. 'Cas, you listen to me very carefully. We ain't dying until we ice the Devil. And when we do, we die like goddamned kings. You got that?' There came a mumbled, incoherent reply, so Dean continued. 'Right now however is the time to stand up.'
Cas sniffed. 'But what if I just fall down again?'
'Then I'll be there to catch you.'
Right now, Dean just looks like a puppet with its strings all cut, open glassy eyes staring into the nothingness of the inky sky.
"You don't look like a king right now, old friend," Cas mumbles, and forces himself to look away from the window.
With a weary sigh, he sits atop a pile of toilet paper, the rolls parting around him like some bleak and lonely throne. He looks down on the cracked floorboards and broken glass, and the air he breathes is all smoke and rotting flesh. Feeling something hard dig into his leg, Cas reaches into his back pocket to find a lighter and a single cigarette. Without hesitating he places it between his teeth, and within seconds he feels the zephyr of tobacco down his throat like molten syrup.
The fire outside is dimming now – there's barely anything left of the tree to burn – but the sky is brightening under the early morning sun. Soon the ominous orange flickering is replaced by the cheery pink and golden light of a sunrise that seems intent on mocking him, as if a new day could possibly bring him a single shred of joy. Cas preferred the fire.
The toilet paper behind his back is damp and clumping scarlet in his blood, but the rest remains bone dry. And as he exhales, watching the tendrils of smoke whisper into nothingness, he gets an idea.
Cas reaches once again for his lighter, and smiles.
Dean died like a martyr, with a broken neck and a broken heart.
With his burning grief and his throne all swallowed in golden flame, Cas dies like a king.