Why is Norton so curious about Mr. Pignati in the book The Pigman? How does John react to Norton's questions? Why?

Norton is
curious about Mr. Pignati because he wants to exploit the old man.  He wonders if the Pigman
"has...got anything worth stealing", and is excited when John tries to divert his
interest by telling him that all the old man's got "are some tools and stuff".  Norton
associates with "this lunatic man on Richmond Avenue who makes believe he's the leader of
organized crime on Staten Island", who will give Norton money for stolen goods.  Norton
wants to know more about what Mr. Pignati has because "there's a big market for
electronics".

John reacts to Norton's questions with annoyance.  At
first he tries to be evasive, hoping that Norton will get the idea that there would be nothing
to gain by harassing the old man.  When that doesn't work, and Norton insists on knowing why he
and Lorraine, whom he calls a "screech owl", go over to Mr. Pignati's place so much,
John changes the subject, getting angry and challenging his lowlife friend for calling Lorraine
by that derogatory name.  John and Norton exchange words, and the confrontation ends with Norton
threatening to "pay (the Pigman) as visit real soon".

John reacts
as he does because he doesn't want Norton to hurt the Pigman.  Norton has a long history of
getting in trouble, and John recognizes that "he's the type of guy who could grow up to be
a killer".  John really likes Mr. Pignati; the Pigman treats him with a love and respect
that he has never experienced before, "and always with a big smile so you (know) he mean(s)
it". has become a dear and important person in his life, and John is protective of him.  He
knows "(he'd) kill Norton if he tried to hurt the old man" (Chapter
9).