Remus Lupin remained an intriguing character throughout the Harry Potter franchise since his introduction in the Prisoner of Azkaban. Teaching Defence Against the Dark Arts during Harry's third year, Lupin became quite the mentor for the young hero. The student-favorite professor's mysterious attributes came to light throughout the series. Perhaps the strangest revelation is that not only is Lupin revealed to be a childhood friend of Harry's father, but he is also a werewolf.
Lupin's beginnings as a werewolf occurred when he was only four years old. His father, Lyall, worked at the Ministry of Magic during the trial of Fenrir Greyback. Greyback's true identity as a werewolf became known to Lyall, who had a clear prejudice against werewolves. After tension and anger between the two men, Greyback decided to go after Lyall's son. A young Lupin slept peacefully in his bed before being bitten and cursed with lycanthropy.
Remus Lupin faced the possibility of being shunned by the wizarding community, given their negative perception of werewolves. Fortunately for him, Albus Dumbledore believed in Lupin's ability to impact the lives of Hogwarts students as a teacher. Dumbledore even convinced Snape to brew Wolfsbane Potion in order to keep him and everyone around him safe. Having more control over his animalistic actions thanks to the potion, Lupin was able to make strong relationships with his students and, most importantly, Harry.
Lupin's werewolf curse could have also been seen as a blessing at one point in the lycanthrope's life. After his time as a teacher, Remus Lupin became a spy, living among suspected Death Eaters to gain some insider information on Voldemort's plans. To do so, Lupin spent a majority of his time in his werewolf form, mingling with other werewolves who sided with Voldemort. Gaining this intel wasn't something he needed to do, but Lupin's desire to seek out danger in support of the greater good was a factor of his character.
Although his presence at Hogwarts was crucial for the main character's development, Lupin's curse also had its downfalls that impacted the Harry Potter series. Prisoner of Azkaban is the first time audiences and the film's protagonists see Lupin transform into a werewolf. During the mission to send Pettigrew to the Ministry of Magic, which would help prove Sirius' innocence, Lupin had clearly forgotten to take his Wolfbane Potion that full-moon night. This forced Sirius to turn into his Animagus form to fend off Werewolf Lupin from Harry and the crew. Lupin's transformation ultimately sends the film's ending into chaos. Pettigrew escapes from their grasp, and Sirius is captured. Remus Lupin also didn't stick around to face the consequences of his mess-up, choosing the easy way out. He decided to resign from his Hogwarts position after being outed as a werewolf. While Dumbledore had gone above and beyond to ensure Lupin's curse didn't affect him, the now ex-professor decided to quit instead of putting up a fight to keep the job Dumbledore thought he deserved.
Remus Lupin was a lovable character throughout the Harry Potter franchise, even given his ability to become a ravenous werewolf. There were many ups and downs that came along with his curse throughout the series. At some points, his werewolf curse benefited and propelled Harry Potter's storyline, while other times, it seemed to set the protagonist back further. Aside from the stigma that surrounded werewolves in the Wizarding World, the strange attribute that plagued Remus Lupin was pivotal in the series.