One area many hope the new show will finally get right is the full story of the Marauders—James Potter, Sirius Black, Remus Lupin, and Peter Pettigrew—whose layered history got heavily trimmed in the original eight films.
The books dedicate significant page time to revealing who these four friends really were, how they created the Marauder’s Map, and why their relationships fractured so tragically. The movies, constrained by runtime, reduced much of this to brief mentions or single scenes.