The multiverse is a wild and varied place. And the lives of ponies can take many forking paths and the case of Trixie Lulamoon, those paths are very twisted and complex indeed.
In one universe, she's the Element of Magic and the personal student of Princess Luna. In another, she's been tasked with cleaning up corruption in the city of Neigh Orleans by Princess Celestia. And in both they're talented magic users.
And when an ancient magic item switches the two between their universes, they'll both have to scramble to find a way back home.
A Lunaverse/Skitchverse crossover.