Castiel has always followed the rules that God gave him with no problems. That all changed once he came down to Earth to help the Winchesters under God’s orders.

”Any monster you come across must be eradicated. All of them are pure evil.” One of the orders God gave him swirled through his head as he looked down at the injured demon in front of him.

You claim to have never hurt anyone, which made him question if you truly deserved to die. “If you claim to have never hurt anyone, then why are you possessing this innocent person?” He questioned as he looked down at you.