He's quiet, listening thoughtfully - and putting that with what Billy had said when they first met, he thinks he has a better understanding of why that would be such a deep fear.

"That's why ye said ye were so worried about being mind controlled. I thought it was bad just from what ye said then, but..." he trails off, looking at the other man sympathetically. "I had no idea."

There has to be something that Billy can do about that, though. Isn't there? "What if ye talked to someone who knows how to fight against that sort of thing? See if they can help figure out a way to do...well, I don't know what. Something, anyway."