"I wouldn't defect but-- I can't serve the dark lord either." And if Barty hated him for it then he didn't know what else to do but he couldn't pretend that he could be something he wasn't. He tried and failed at eighteen, it wouldn't change now he was older. "I don't know what I'd do because I never had to -- to consider any of this."

His parents decided his fate. He did everything he could do to be perfect for them, followed everything they said, did all he could and yet he still couldn't convince himself to follow the Dark Lord. He didn't believe what he was told any more and that made it harder to play along.