The time streams are in disarray after Twilight and Starlight's escapades. Continuity is threatened, and futures that shouldn't be are at risk of bleeding over into the consensus reality.

Princess Luna's on cleanup duty, leaving her with the task of travelling to all the likely outcomes and making sure they stay within their own continuities, so no villains turn out to have not been defeated in the present. A usual night of travelling outside of her body and fixing things.

Unlike usual, she gets some company in the form of a draconequus. One who apparently has some things he needs to get off his chest, regarding how he's been treated and all the other villains have.

Seems Luna's not the only one with a few chips on her shoulder...