Wolfstar

Lupin is a half-blood, born, according to the series, to wizard Lyall Lupin and his Muggle wife Hope Howell on 10 March 1960. He was bitten by the vicious werewolf Fenrir Greyback when he was a small child, and became infected with lycanthropy; the condition being incurable, he was doomed to live his life as a werewolf. Lupin and his parents feared he would be unable to attend Hogwarts, but headmaster Albus Dumbledore allowed him to enroll—provided certain protective measures were taken. A house was built in Hogsmeade with a secret passage leading to it from under the Whomping Willow. Lupin was smuggled into and confined in this house for his monthly transformations. The transformation from human to werewolf is difficult and painful, and if the creature is isolated, it will become frustrated and harm itself if unable to attack. The villagers mistook Lupin's howling as extremely violent ghosts. The house was dubbed "the Shrieking Shack" and became known as the most haunted building in Britain. Although it was never actually haunted, Dumbledore promoted this rumour to discourage curious villagers from exploring.

When Lupin started Hogwarts, his condition was kept secret, but James Potter, Sirius Black and Peter Pettigrew deduced the truth in their second year. By their fifth year, they secretly and illegally learned how to become Animagi to keep Lupin company during his transformations. His lycanthropy was not transmittable to them in their Animagus forms, nor was he a threat to them while they were animals. Additionally, James and Sirius' Animagi, a stag and a large dog, were large enough to control a werewolf. His friends nicknamed him "Moony" for his condition.

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Sirius Black is the last heir of the House of Black, a once notable Pure-blood Wizarding family. His parents, Orion and Walburga Black, were both Blacks by birth and second cousins. Sirius had a younger brother, Regulus Arcturus Black, and three older cousins: Bellatrix Lestrange, Andromeda Tonks (his favourite cousin and mother of Nymphadora Tonks), and Narcissa Malfoy (mother of Draco Malfoy). In line with the Black family tradition of naming children after stars and constellations, Sirius was named after the Dog Star. Sirius's early life proved unhappy; he had come to hate most of his relatives, in particular his mother. He rejected his family's pure-blood elitism and reverence for the Dark Arts. At Hogwarts, rather than be sorted into Slytherin like the rest of his family, Sirius was placed in Gryffindor.

In contrast to his home life, Sirius greatly enjoyed life at Hogwarts, where he was inseparable from his best friend, James Potter. Sirius and James were immensely popular and known for their exceptionally good looks. Students liked his biting humour, and teachers respected his intelligence, though not his behaviour. His popularity was not universal, as a mutual hatred sprang up between James and Severus Snape. Sirius actively supported James, leading to Snape developing an equal and lifelong loathing of Sirius. Sirius and James often went out of their way to bully Snape, whom they despised for his great interest in the Dark Arts. They also became best friends with Peter Pettigrew and Remus Lupin, whom they later discovered was a werewolf. To support Remus, Sirius, James, and Peter secretly became Animagi, which allowed them to safely accompany Remus during his transformations and keep him under control. Sirius's form is that of a huge black dog, from which his nickname Padfoot was derived.