What is an important theme in The Subtle Knife by Philip Pullman?

One major theme in the novel is that of authority, technically, the way the youngsters, Lyra and Will, react to different types of authority. Will is protective...... he seeks to mislead authority figures in order to take care of his mother..... to protect her and their relationship. Lyra, on the other hand, responds to authority by lying and misleading those who wish to control her. Together, Lyra and Will band together to protect each other from those who wish to hurt them.