In the novel there are a few quite significant charcters that aid the progression of the story, but most of them are just second fiddle for the most important charcters, Carl, Harley and the Duncans.
Carl Matt is the protagonist of the story and has 2 siblings, an elder sister and a younger brother. Along with his brother he moves to Wattlebeach after being deserted by the rest of the family. He is 15 years of age and doesn't stand out much, he usually stands on the sidelines watching others live their lives and has a very low self esteem.
Harley Matt is Carl's younger brother, he moves to Wattebeach with Carl where they live with their aunt. Harley is a troublemaker and quite stereotypical of the Matt family. In his first few weeks at their new home Harley manages to upset the locals and cause embarassment for his aunt and brother. He is a naive little kid and acts out since his mother hadn't cared for him when they were in her care.
The Duncan family consist of three people, Joy,Skip and Maddie, the Duncans have a past with the Matt family which have caused them much grief and shamed the Matt family. Skip the man of the family works on a barge where he earns little income for his low passenger trips and his quite bossy and stubborn. Joy is Skip's wife and Maddies daughter, she doesn't work and stays at home most of the time. She is kind hearted and help guide the Matt brothers. Maddie is a 15 year old girl like Carl and is in love with a boy named Nathan Trelfo who doesn't care much for her. She is kind hearted but naive.