[his face lights up as though Peter had just called him 'Dad' or something. but then Peter adds something that confuses him, and two more things which just plain make him upset]

Teenagers are always going to come up with terrible nicknames. Sometimes I wonder if it's a rite of passage. ... I'm sorry about your uncle. The Peter I know lost his, too. I don't know much about it, only what Harry was able to tell me.

[he reaches out and puts a broad, warm, reassuring hand on Peter's shoulder] Y'must miss him every day. It was like that when I lost my mother.