Something from Kaworu's body language and expression says he's heard a lot of this before, but he's politely sits and listens anyway. Billy's a kind person, but he won't be convincing Kaworu that things wouldn't be different between them if he was a Lilim from his world who knew what he was.

As he listens with half his attention, he watches Billy's nervous fidgeting.

"Am I interesting?" he asks. Billy's a scientist, so it's not that surprising. And Kaworu's dodged a lot of his questions in the past. His eyes move down to the floor as he silently asks himself whether he should get into this topic with him.