What if Pitch had won. Using the fear he had gained he would unleash it on the guardians(except for Jack since he wasn’t officially a guardian until the end of the movie) transforming them into evil versions of their original selves. Pitch would use their new forms as ways to insure that fear and darkness would forever be in the hearts of children.
With this AU playing out in my head, I imagined evil tooth and her little helpers would being based off a crow or raven instead of a hummingbird. Since she was the guardian of memory, her power over that aspect of childhood would still be there, only there would be a twist too it. Her job now would to keep the teeth and withdraw the bad memories within it. since the bad memory is so deep with in the tooth once the process is done the tooth decays a bit, leaving it looking like a cavity.And every so often the fairies would remind the child of its bad memories when needed, so that the kid never forgets their bad experience and letting the fear back in.
Hope you enjoy