Why does the author use flashback in the story ?

The author uses flashback in a few different ways. First, the flashbacks allow the reader to see how Cole got to where he is.... the story, the punishment, the refusal to take responsibility. He isn't just on an island.... he is banished. It isn't supposed to be all fun and adventure.... it's supposed to be an eye-opening, life changing experience. The use of flashback also enables the story's narrator to fill in the blanks, look at the situation from the outside, all while knowing what's going on inside of Cole's mind.