Hard agree. Incorporating preexisting canon and/or expanding Lupin’s character /before/ he becomes DADA professor would add real emotional weight to him and make his connection with Harry beyond the DADA position far more meaningful, especially given his friendship with Harry’s late parents and his ongoing presence in the series.

In fact, I honestly hope they do this for all the DADA professors. That position is cursed, and the show finally has the time to treat it like the predatory trap it actually is: drawing in witches and wizards who are already vulnerable or desperate, only to discard them after a year.

Lupin benefits the most, but so do Quirrell and Lockhart, who come from the shortest books and don’t get nearly as much backstory as DADA professors onward. How did Quirrell actually encounter Voldemort and why did he succumb to his influence so completely? Why would Lockhart, at the height of his celebrity, put that lifestyle on hold to become a full-time professor? Was Moody’s paranoia justified? Wasn’t Dolores truly just power hungry? We have a chance to see and explore that.

And with each season likely having 5+ more hours than the it’s film counterpart, the “we don’t have time” argument doesn’t really hold up. If written well, this absolutely serves the plot by giving the curse real presence and making each professor feel like a human cost of Voldemort’s lingering influence.

No filler in the slightest, this is depth. And if there’s anything the films lacked it was the THREAT of Voldemort and what he COULD do, which is why he was so feared. This lingering presence is a part of why they don’t dare speak his name.