When we first meet Percy, in Harry Potter and the Philosopher's Stone, he is a prefect, and in Harry Potter and the Prisoner of Azkaban he becomes Head Boy. He is relatively humourless, and thus the butt of many of Fred and George's jokes and pranks.
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In Harry Potter and the Chamber of Secrets, he is shown to be behaving in a secretive manner, perhaps as a red herring to lead the reader to believe he is responsible for the opening of the Chamber of Secrets. It later transpires that he secretly has a girlfriend, Penelope Clearwater, a Ravenclaw.
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