I feel that one of the themes is that racism and hatred can ultimately destroy the person who is guilty of it. Bruno's father is happy to kill children of Jewish families and it is the ultimate irony that he indirectly kills his own son. It is also clear that it is adults that are the ones who are guilty of racism as children play happily with each other and do not see race/colour etc.
The role of women is explored too as Bruno's mother is not really at ease living near a concentration camp but does not speak out; speaking out may have saved her child's life.
The Nazis' hatred of other people and their casual mistreatment of them is characterised in the form of Pavel who helps around the house although he is really a doctor.
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Not once! this question is asked many times! el o el