Complex sentence: He is shown to admire the Joker, until the latter disfigures him with a razor; however, he sees his disfigurement as an opportunity to give up his old life and become a sadistic monster permanently.
Split into simpler sentences: He is shown to admire the Joker, until the latter disfigures him with a razor. He sees his disfigurement as an opportunity to give up his old life and become a sadistic monster permanently.