Argus Filch is the Hogwarts caretaker. He is a Squib, a fact he tries to keep secret from the students. He has a very loyal cat, Mrs Norris, which aids him in his duties of keeping up the rules in the school. Filch's knowledge of the school's secret passageways is second to only that of Fred and George Weasley. He is in a constant war with Peeves the Poltergeist and also Hogwarts Students. Filch is first discovered in Harry Potter and the Philosopher's Stone, Chapter 9, The Midnight Duel.