The head of a school is a princi-PAL. A princi-PLE is an idea or a rule.
As I understand it, Henry is a physically small boy. I was all too familiar, in my teenage years, with the humiliations of being small. Even if you don't get bullied, you DO get treated as less valuable than tall people. Where is Henry going? If something doesn't happen to prevent it, I see him becoming a VERY bitter man, trying to get revenge on the unfair world.