He doesn't know how to fix this. The flayed soul retches and screams, soundless and deafening at once. Cowers from the touch of renewed grace meant to heal, never hurt. There is nothing for it. But that is what so many had believed of the Apocalypse as well. The Winchesters have a knack for overcoming impossible tasks, and Castiel is no stranger to doing his part. Sam's soul was once bright, even when weakened by Ruby's tainted influence. Castiel plans to make it so once more. He will mend it; every tear, every gash. Stitch by stitch if he must.