Work Text:
I've never read the Hogfather before, but basically in the story the tooth fairy used to be a boogeyman sort of figure before deciding to go good or something like that. Interesting story in and of itself, and the idea of Tooth being evil before is fascinating.
But, me being me, I had a better idea.
All of the guardians used to be evil.
North used to be Krampus, punishing kids for being naughty before realizing that positive reinforcement worked better.
Bunny was more of a mythologically accurate pooka, the man-eating fae ones who trick people and look really creepy. But then Bunny started doing Easter and used his shapeshifting powers to look more child-friendly. No idea why he decided to change, but he did. And he's not actually Australian, he just thought Australian stuff was really cool so he practiced the accent and adopted the boomerangs and all that.
Tooth used to be an evil fairy witch who used teeth to cast spells which was why in Europe teeth were buried or burned to prevent witches from using them in curses. But then Tooth made her mini fairies and she turned over a new leaf after becoming a mother and decided to take care of other children too.
Sandy used to be the sandman that ETA Hoffmann wrote about, the one who steals kids' eyes if they didn't sleep, but then the man in the moon told Sandy to take a page out of North's book and Sandy found out that positive reinforcement actually did work better and Sandy used his sand to make dreams instead of making kids' eye sockets bleed out.
The plot really kicks in when Pitch arrives and instead of thinking about defeating him, the guardians are thinking about how to reform him like they did since fear is an important part of people's lives.
Cue a very confused Pitch when the guardians he thought were just about innocent childhood stuff revealing their dark pasts and explaining the benefits of a redemption arc.
Jack probably doesn't show up in this fic until about three hundred years later, but if he does, then maybe he can be like a younger incarnation of Old Man Winter who decided to stop making blizzards that killed people and wanted to be the kind of person who instead made snow days for kids to skip school and just have fun.
For added humor, not all of the guardians knew that they weren't the only reformed boogeyman-ish spirit so when they start talking to Pitch there's a short 'wait, I thought I was the only one' thing as they realize that literally all of them were reformed dark spirits.
Some of them probably worried that the others would stop being friends with them if they divulged their dark pasts but I suppose that's not an issue now.