Who is Colin Singleton from An Abundance of Katherines and what is their importance?

Colin Singleton is a senior in high school. He has a habit of dating girls named Katherine. When the novel opens, Colin was dumped by his nineteenth Katherine. While Colin is a genius at school, reading and educational aspects of his life, he is not successful in simple human interaction. As an only child and a genius at that, Colin's parents have devoted their life on focusing in on Colin's intelligence, but have neglected to focus much of an effort at all on his social interactions with other children his age.