Remus Lupin, a beloved professor at Hogwarts, is a werewolf in the magical world of Harry Potter. Werewolves are individuals who can transform into wolves under the full moon. Fenrir Greyback, another werewolf, tries to turn as many people as possible into werewolves to create an army. 

Bill Weasley, a member of the Order of the Phoenix, suffers a cursed wound from Greyback but does not become a werewolf. Lupin, however, was bitten by Greyback as a child and became a werewolf. He attends Hogwarts with the support of Albus Dumbledore and his friends, who become Animagi to accompany him during his transformations.

Lupin tries to control his condition by taking Wolfsbane potion but faces employment challenges due to the stigma surrounding werewolves. 

He eventually marries Nymphadora Tonks and has a child with her before they tragically die during the Battle of Hogwarts. Despite this, their child does not inherit lycanthropy, as it cannot be passed down genetically. The Harry Potter franchise follows a young boy's journey as he faces challenges, battles Voldemort, and becomes a hero.