billy discovering sinclairs existence was probably so messed up because imagine being billy and having to live with your uncle because hes the only family you have, and hes awful. hes awful and he hates you and theres nothing you can do to make him not hate you so you run away and end up being homeless at age 8. you grow up and try to convince yourself that none of it was your fault-he was the worst possible guardian, you were simply in the crossfire- but then you find out he sold his soul. hes now a soulless husk of himself chained to a demon because he wanted something so damn much he was alright with selling it. and then you find out he got a son from it.
He looks just like you.









