Flash Sentry is not the most attentive student in Canterlot High. He is not the smartest or the fastest or the most assertive. He is not a lot of things, but he does try to be a good boyfriend, and an even more normal teenager.
But one fateful day he becomes the only person on Earth to have a talking pony in his closet. A pony only he can see. A pony that is incredibly, stupendously annoying.
The incredibly dangerous, stupendously powerful things that followed him to Flash's world, though... those are another matter entirely.