A thousand years ago, Princess Celestia banished her sister to the moon, that much we know. What wasn’t known, and what Celestia kept secret was that before her banishment, Luna had given birth to a foal. Now a thousand years later, as Nightmare returns to Equestria to bring about Eternal Night.

Twilight Sparkle, protege of Princess Celestia, struggles against the tyranny of this ancient foe. But how will she be able to save herself and her friends when the truth of this ancient legend crashes down upon her? Twilight will have to confront herself...and her heritage.

Polaris501

The foggy feeling like you're wandering through a dream, disconnected from the world around you. Sunset Shimmer experiences that every day. Ponies struggle to remember her, she suffers from random bouts of exhaustion, and at eighteen, she still has no cutie mark.

Despite the claims her mother makes, Sunset knows she is broken in some way. It isn't until her nineteenth birthday that she discovers why.

When her perception of herself and the world around her shatters, Equestria will face the consequences of the villain... or the hero, it was never supposed to have.