After getting shoved into a biohazard-filled locker and triggering as a parahuman, Taylor Hebert spent four years in Equestria before she could find her way back. Now that she's in her home universe, she has to deal with being a superhero who is substantially less screwed up than all the other ones are.

This is a crossover with Worm. If you haven't read that, you should, and not just because this will make much less sense without it, but also because it's a good story, albeit pretty dark.