The novel Fly Away Peter has central themes based around the concepts of change, transition and development. The book explores these ideas through its main character Jim Sadler.
Jim begins the story in a state of blissful innocence. He has a simple lifestyle and only one passion, that of the birds. Slowly Jim gains life experiences through his constant hawk-like awareness of what is happening around him. He picks up valuable details and learns crucial knowledge about his surroundings and the people within them due his heightened state of awareness.
This awareness allows Jim to develop himself faster, and in another way compared to the average human being. Most people let life pass them by, and don't take note of the small but often crucial details. These small details enabled Jim to mature and see the man that he wanted to be. He takes a severe interest in his own "dark side" when he is confronted with Wizzer on the battle lines. His sixth sense allowed him to see that this is not the person that he wants to be. As a result he shuts this violent side of himself out as much as possible. Unlike most people, Jim is capable of assessing a situation and making a well-educated and informative view on this. During his altercation with Wizzer, he takes note of the fact that the two men were ready to "kill" as opposed to when Clancy takes the fight away from Jim and ends up "wearing Jim Sadler's black eye.".
Initially, Jim did not wish to join the war, but his opinion swung. Jim realised that this was a momentous occasion in history, a moment that would define the world as it moved into the future; and he would not fully understand the world or what the war meant, unless he experienced it for himself. He was not convinced to join up by his father's constant heckling, or because of mateship and he did not bow to peer pressure. He made a decision for himself based on his own beliefs and ideals. The belief that he would miss out, that it was now or never.