This is the story of how an angel falls from the sky.
This is the story of how Dean gets to hold him in his arms for the last time, as they say their farewells.
None of this is fair. Not now, when they finally got the courage to tell each other the three words they should have said years ago. When they finally got to be happy.
But then, that was the deal; Castiel's happiness becomes his undoing.
His deal with The Empty is probably the dumbest thing Cas has ever done on a long list of dumb things. But it is also that: done.
And there isn't any way to get out of it this time, no loopholes, no ancient weapons, no dei ex machina. The deal's binding and unkillable, and so is The Empty. Impossible, it seems, after all that they've been through, all the things that were supposed to be unbeatable too.
And for a long time Dean fought, he read every littlest footnote of every book in their library. He asked every single person, every single thing in creation that he knew.
He asked God, himself. And Death, and Amara.
And they got him nothing.
No angel can escape The Empty's claim, they all said, not when it's this dead set on putting its slimy claws on them.
No angel.
Unless—
Unless he's not an angel anymore.
Unless he's not himself anymore.
The idea isn't new. It's been on their minds for weeks now, long before Dean risked his life, possibly more, to find something, anything that wasn't...that.
That final. That forever.
But, at least, it'll be gentle. At least, it'll give Cas a new chance at life. Something he could really, really use. And more than deserved.
He'll get to forget all that he was, and all the wrong that he's done with the best of intentions. He'll get to start in a way that has never been written for him, an angel. He'll get to be a kid, get to experience the innocence of it, the pure exhilaration of it; get to grow up and become his own person, whoever he'll be.
And Dean can only hope — will hope with his whole heart — that this new, human life is simple and treats him well. That it lets him breathe and laugh and discover the world, and himself. That it lets him then grow old and leave softly, rest in Heaven, as the good ones are meant to do.
And that he loves.
That he's loved.
The way Dean loves him. The way he'll love him long after he's gone. The way he won't get to show him every day, in doubling his bacon for breakfast and in holding him at night, in massaging out the knots in his muscles and in learning all the words to Cas's favorite songs.
In fighting side by side until they can fight no more.
Dean holds his breath, lips pressed into a tight line. He can't cry. He can't make this harder than it already is. And it's so fucking hard.
He's losing him.
He's losing him.
He's losing him.
And he's taken him for granted for so long. The guy who'd die and come back, over and over again, even after Dean gave up hope.
"Maybe we should let it take you, we'll bring you back, like you came back—"
He doesn't care if his voice crumbles, doesn't care if he stabs daggers into Cas's heart. He can't let go. How is he supposed to let him go?
But they've been through all of this already, every possible scenario.
The Empty, it's got a golden cage waiting for him, in the very center of the endless darkness. It'll never let its claws off him, never let him out of its sight, He'll be its favorite pet, its favorite chew toy. Among those in eternal slumber, they'll never get to fall asleep.
That they can't risk. That Dean would never forgive himself, he'd never stop looking for a way to bust him out, whatever it'd take.
It's why Cas even agreed to this, instead of giving himself up; Dean knows that, though he never said it aloud. A new life for Cas, and peace for Dean. The end of their story before it got a chance to really begin.
"It's coming."
Dean's body stiffens. He forces each muscle after muscle to pull away from Cas, for the last time.
This is it.
It's their last kiss, last press of lips too brief to even taste it.
This is it.
A goodbye, the last time Dean hears his lover's voice, last time under his stare, last time—
This is it.
The bright light pours out of Cas, out of his vessel, blinding, yet Dean braves it until he can brave it no more.
There's an empty body lying on the ground where Cas stood.
There's The Empty, as a curtain of blackness against the starlit sky, rising up to Heaven; a wrathful bird chasing its prey.
They were too late, oh God, they were too late. They held on too long, now it's the deaths ugly embrace that'll hold him tight. And Dean's gripped too, by the choking, suffocating feeling clenching his lungs in its fist.
But then the shadow clears and Dean can breathe again. Up, on the dark, northern sky, its fabric's cut through by a trail of white, of a new life plunging toward the Earth as a shooting star.
The shooting star.
Castiel.
He made it.
He'll get to live again.
Dean'll have to live on.
"The other one went south, Great Falls maybe."
Dean doesn't look at his brother.
He doesn't want to be seen. Or to move or to drive for miles just to scoop Cas's grace, the last piece of Cas he's allowed to hold, into a vial to stash it safely in a box, in a safe, in the depths of the bunker, just to keep it away from prying eyes, away from anyone's temptation.
Away from the light, in its own nothingness, Dean'll keep it protected, forever.