Peter Pettigrew is a Gryffindor at Hogwarts school and a canon character in the Harry Potter books. He is an animagi, having the ability to turn into a rat at will, and thus earning him the nickname "Wormtaill" from his close friends James Potter , Remus Lupin and Sirius Black .
In chapter 35, "All Soul's Day" we start seeing how Peter starts losing his faith in that the good side will win the war.
After "the Life and Times" Edit
Peter Pettirgrew is made Lily and James Potter's Secret Keeper when they go into hiding. This was by request of Sirius Black, who was afraid he wouldn't be able to keep the secret under pressure from Death Eaters and Voldemort, also Sirius thought no one would suspect Peter of being the Secret Keeper. But Peter had already turned on them and become a spy for Voldemort. He reveals Lily and James hiding place to Voldemort, and in the end, it is Peter's fault that Lily and James dies. On the night of Lily and James' murder, Sirius hunts Peter down, but Peter escapes, making it look like Sirius killed him. Peter spends 12 years in hiding in his animagus form at the Weasleys, as Ron's pet rat Scabbers.