What are the motifs in King of Shadows by Susan Cooper?

The love of family is a recurring idea in the novel. The main character's definition of family has been disrupted from a very early age. When his mother dies of cancer, and his father kills himself shortly afterward out of grief, Nat is left abandoned and moves in with his aunt who continues to raise him. While his aunt is a caring guardian, Nat lacks a father figure on whom he can rely.