This happens after the events of the episode Amending Fences. In the same universe as pinkies guardian angel.

Trevor was a normal guy living a normal life until the day he woke up in Sugarcube corner to find out he must guard the pink party pony Pinkie. Nopony can see him but they all can hear him how will Pinkies friends let alone Equestria survive?

This is the story of Evan and his adventures through the parallel universes in the season five finale.