The major theme in this book is guilt and it is played out between the main characters who are Lorraine (a high school sophomore, a friend of John), John (a high school sophomore assigned to a project with Lorraine) and Mr. Pignati (an old lonely man who lives in Lorraine's neighborhood).
The first time the characters of the book experience guilt is when John and Lorraine were upset for lying and taking the money from Mr. Pignati. To compensate for this feeling, they agree to go to the zoo with him. This is a very important part of the book because if they had not gone to the zoo with Mr. Pignati, they wouldn't have gotten to know him and would not have written their story.
Another time when John feels guilt is when his father says, "The business can be half yours, and you know it. I can't take the strain much longer." John stated that "Every time he says that I feel a little sick to my stomach because I know it is true. He's almost 60 years old and not going to be around much longer." In this part of the story John feels guilty because he thinks his dad is going to die soon and he has been mean to him for a long time.
Lorraine also feels guilty for letting Mr. Pignati buy her and John all the gifts because she had been lying to him about her identity. Here is an example from the book to show this.. When I came out, John was yelling "Hurry up!" I asked what for and he replied, "Mr. Pignati is going to buy us roller skates." Lorraine answered, "Oh no he isn't! He's spent enough money on us!" This showed guilt and some compassion because Lorraine didn't want Mr. Pignati to spend all the money on them.
Another incident that happened which caused Lorraine and John to feel guilt was when they encouraged Mr. Pignati to put on roller-skates. They felt that it was because of them that he fell down the stairs and had a heart attack. This was an important part because Mr. Pignati almost died from the heart attack and Lorraine felt as if it were her and John's fault.
Throughout the story, events that created feelings of guilt within the characters happened frequently. John and Lorraine felt guilty for a lot of things they did to the " Pigman" as well as to other people, as they were always doing something wrong or causing trouble. Guilt is something everyone feels and this book had some very good examples of it.