What is the theme in King of Shadows by Susan Cooper?

Grief is a central theme to the novel, as seen through the main character, Nat. Nat is an orphan who is being raised by his aunt. Nat's mother died of cancer, and shortly after, his father commits suicide out of grief. Nat finds his father's body lying in a pool of blood, and has the image permanently ingrained in his memory. Left parentless, he moves in with his aunt. Nat and his aunt do not discuss the death of his parents, denying Nat the ability to grieve and move forward. At the recommendation of his aunt, Nat begins to act in community plays as a distraction from his sadness. Nat quickly takes to acting, and excels in the theatre. With acting as a distraction, Nat further distances himself from the grieving process.