"I'm sorry, Dean."
And the world falls apart.
Rushing in his ears, pain, pain, pain, but freedom— the souls leave him, and he can hear them screaming, howling, hissing, and the gate to Purgatory closes— but he's not empty.
Not yet.
His eyes slip closed and he falls and no one catches him.
And he can hear them singing praises inside of him, feels them boiling up, up, up, snapping his eyes back open, shoving him to the back of his own head, running his veins black, smiling.
Castiel had wanted to scream, before. Out of pure curiosity.
Castiel had wanted to be afraid, before. Just to see how it felt to be the one begging for mercy for a change.
Now: Castiel is screaming, Castiel is afraid, Castiel is begging for mercy, clawing at the walls of the prison inside his mind, reaching out for help, but the Leviathan laugh at him, laugh at his pain, and close the gate a little further.
Castiel calls out to Dean, begging for help, begging for forgiveness.
Castiel reaches out to be held.
But the Leviathan push him further back and laugh at the terror in Dean's eyes, at the pure revulsion with which Dean shrinks back, away, leave Dean breathless with fear on the ground—
And the last emotion Castiel sees in Dean Winchester's eyes before the Leviathan swarm Castiel, drown Castiel, tear Castiel to shreds—
the last expression Castiel sees on Dean Winchester's face—
that face he rebuilt—
that face that taught Castiel how to feel—
that face that Castiel sees every time he closes his eyes, even now—
that face that hurts and heals and spits and curses and smiles and laughs and cries and kisses and calls and drinks and completes and loves—
the last glimmer Castiel sees in his eyes—
is hatred.