Who is Tommy. from Last Exit to Brooklyn and what is their importance?

Tommy is a decent, popular and attractive young man who ends up having to marry his pregnant girlfriend Suzy. He represents the problems caused with young people having to jump into marriages with people they may have little in common with. At the end of the book, the author suggests there will be future problems when Suzy goes home early from the wedding banquet. Though Tommy thinks about going home to look after the child, he eventually leaves with a girl called Roberta.