Once upon a time, there lived a human in Canterlot simply named "Sunset." She was the prized pupil of the Sun Witch Celestia (aside from Celestia's adoptive daughter, Cadance) –– her "little solar flare." But Sunset desired more than status; she wanted power –– she wanted to be a Witch. For when she looked in the mirror, she no longer saw a lowly human, but the Fire Witch she was meant to be.

The more Celestia denied her desires, the stronger her animosity grew. One night, Sunset performed a dark, forbidden ritual to commune with the spirit world and grant her a Witch's body. But the ritual backfired when Celestia stormed in. In the ensuing chaos, a piece of Celestia was transferred into Sunset and three wicked spirits were released into the physical world: the Siren Sisters –– Aria, Sonata, and the most powerful, Adagio.

Despite her best efforts to contain the sirens, Celestia could not stop them from escaping to Earth where she could not reach. Distraught, betrayed, and heartbroken, Celestia banished an inconsolable Sunset to Earth. Only once she vanquishes the three spirit blights she brought upon this world will she be allowed to return home.