What metaphors are used in Sir Thursday by Garth Nix?

Paul Hasleman, age twelve and presumably in the sixth grade, lives in an American town, probably in New England. Prior to the onset of his madness, Paul was an ordinary boy, good at geometry, and excited about geography. At first he is considered introspective, but it is soon clear that he is detached from reality; this alienation is metaphorically represented in this story as the secret snow.