Princess Eclipse

When Twilight Sparkle enters the Castle of the Two Sisters to find the Elements of Harmony, she instead finds Nightmare Moon-and a choice. Tempted by promises of purpose and recognition, she accepts the darkness and is transformed into Princess Eclipse, the alicorn of silence and order. Her reign is powerful, revered, and quiet... but each year, she returns to the place where she was remade, haunted by what might have been.