Why did John get interested in Mr. Pignati in The Pigman?
They were making crank phone calls and called Mr. Pignati. They said they were collecting money for a charity. They go to Mr. Pignati's house to collect the money. This is the start of how they get to know him. Eventually they become close friends, sort of, but really it is Mr. Pignati that is willing to become like a father figure for the two. Their parents are unavailable and so they don't really have any guidance in their lives. They really like him because he gives them his time, unlike their parents who either do not have time, in the case of Lorraine's mother who has no husband, or who are mostly interested in making money like in John's case. His father is a stockbroker.