When readers first meet Percy in Harry Potter and the Philosopher's Stone, he is a prefect; 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.
In Harry Potter and the Chamber of Secrets, he is shown to be behaving furtively (perhaps a red herring with which to lead the reader to suspect he is responsible for the opening of the Chamber). It is later revealed that he secretly has a girlfriend--Penelope Clearwater (a Ravenclaw).
In Harry Potter and the Prisoner of Azkaban, he reached his final year at Hogwarts. He graduated in June of 1994 at the age of seventeen, and soon started working for the Ministry of Magic under Mr. Crouch (whom he looked at like something of an idol in Harry Potter and the Goblet of Fire). In Harry Potter and the Order of the Phoenix, he was promoted to the status of Junior Assistant to the Minister of Magic by the Minister himself (Cornelius Fudge); this prompted a personal and political dispute with his father (Arthur Weasley), which resulted in Percy’s subsequent alienation from his family.
In the films, he is played by Chris Rankin.
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