Sirius greatly enjoyed life at Hogwarts, where he was inseparable from his best friends James Potter, Remus Lupin, and Peter Pettigrew. Remus, they later discovered, was a werewolf. To support him, Sirius, James and Peter secretly — and illegally — became Animagi, which allowed them to safely accompany Remus during his transformations and keep him under control. Sirius' form took the shape of a huge black dog (not unlike the Grim), from which his nickname "Padfoot" was derived, James would become a stag (Prongs), and Peter would become a rat (Wormtail). The four friends called themselves "the Marauders" and used the nicknames "Moony, Wormtail, Padfoot, and Prongs," Padfoot, Prongs, and Wormtail after their three Animagus forms and Moony after his lycanthropic condition. They would, during their time at Hogwarts, create the Marauders Map which allowed them to see where everyone in the castle was at a given time which made sneaking around and avoiding teachers much easier. They were very bright wizards, and in Harry's third year, he gained whole of this map by Fred and George, who took it from Filch. Although he later considered himself "an idiot" during this time, Sirius, along with James were immensely popular: teachers respected his intelligence, though not his behaviour and girls adored his dark handsome looks, but his especially rebellious attitude made him ignore them, therefore making the girls fawn over his bad boy attitude. Many teachers regarded him and James as troublemakers or practical jokers; Hagrid once compared them to the mischievous twins Fred and George Weasley, saying that the Weasleys could "give them a run for their money".