Arthur Weasley, Alastor Moody & Ted Tonks as old school friends, maybe brief post-grad flatmates? General bromances because they're <3. Dorcas Meadowes as his auror apprentice for proud mentor stuff and eventual feels (only the good die young. I have thoughts, come chat). Dolores Umbridge for epic Office Space crankiness. Barty Crouch Jr. for cat and mouse evil and stuff. Rufus Scrimgeour because yes. Aberforth as the quintessential sage bartender everyone doesn't know they need. A younger sister (Zoe Kravitz would be amazing). A on/off, super rocky lady love who's been falling in with the DEs to complicate his interest in joining the Order. Younger McGonagall for head-shaking (Streep? Mirren?) All the stuff and more. Lets work things out!