Peter Pettigrew

Also known as Wormtail, Pettigrew became one of the Marauders along with best friends James Potter, Sirius Black and Remus Lupin. Together, they created the Marauder’s Map. During the First Wizarding War, Pettigrew was part of the Order of the Phoenix, but became a double agent and defected to the Death Eaters. He became a Secret-Keeper for the Potter family when they went into hiding with the use of the Fidelius Charm, but betrayed them to Lord Voldemort. After Voldemort’s fall, he faked his own death and framed Sirius for betraying James and Lily Potter. He spent 12 years in his animagus form as the Weasley family’s pet rat, Scabbers. His identity was exposed by Sirius and Remus and with nowhere else to turn, he sought protection in returning to the services of Voldemort. When his loyalties affect his services, he indeed gets his comeuppance.