Sirius Black: Naughty - Matilda: the Musical.  Listen to it, you'll understand why I chose it.

James Potter: What is This Feeling - Wicked.  Describing his relationship with Snape.

Remus Lupin: Demons - Imagine Dragons.  I see this characterization I see a lot, so I hesitate to put this, but I feel like he really does see his werewolf side as a demon.

Peter Petegrew: Disappear - Dear Evan Hansen.  He tends to disappear into the background of the Marauders, and it turns out he was playing them the whole time, just not with as good of intentions as Evan.

Lily Evans: Schuyler Sisters - Hamilton.  This one was the hardest.  It was either this or My Grand Plan - The Lightning Thief Musical.

The Entire Marauders: Who Lives Who Dies Who Tells Your Story - Hamilton.  They have almost no canon school-age stuff, so it's mostly the fandom telling their story.