because I just love Megstiel a lot I'm sorry. (but basically this is set after s9. I don't know if Dean and Sam are dead but they're just not around, heh)
Cas can feel the stolen grace gushing out, flowing from his vessel as if it were a tangible torrent.
He collapses to the ground, keeling over as a sharp pain clings to his abdomen. He cries out, but he knows no one will come; there is no one left to cry, no one to mourn him.
This is a truth he has come to terms with. A being such as he deserves no fanfare, no bang to go out with. Not an entity such as he, one who has caused so much strife to his own kind, one who has abused his power and hurt those who believed in him.
Perhaps, Castiel decides, to allow him to perish in such a self-contained way is the Father’s show of mercy. A death which no one else will be hurt by.
Bright, white lights cloud his vision, the room around him disappears in the beams. This is his stolen grace giving out, this is the end of his existence. He leaves only two regrets. His demon and the two brothers, all victims to his carelessness, each a loved one he couldn’t save.
And then she steps into his view. She looks the same as he remembers her. The twisted, black soul painted with thin strands of light. A demon who had begun to cure herself. A demon who fought for him and gave her life to save his.
She smiles. “We’re going to heaven, Clarence.”
“Meg,” he replies, but his voice comes out weak and strangled.
The demon reaches her hand out to the angel; a promise of a forever.
Cas takes her hand. “We’re going to heaven.”