During an evening performance at a private manor, Octavia is shown one of the rarest and finest instruments known to Equestria, a Stellar Variance cello. Just being in the same room as one is a dream come true for Octavia, but then she is given the chance to play it. It is an opportunity Octavia can't pass up, no matter the consequences.

Yet, the next morning Vinyl finds herself at the same private estate, searching for the friend and roommate who never came back.

This story is a sequel to Past Sins

When pursuing Starlight, Twilight and Spike experienced variances of Equestria, and saw how the river of time could have been different. Now, Starlight has moved in with Twilight, Nyx, and Spike and has begun her studies in friendship. To thank those who have helped her embrace friendship once more, Starlight has created an enchantment that allows the castle’s map table to let anyone glimpse other variances of reality.

The power to ask “what if,” can be a source of great amusement… but for some, the hypotheticals are haunting reminders of what could have been.

On the day of the Friendship Games, the veil between two worlds is pierced. The magic of Equestria seeps through the barrier to permeate the world of humanity. Entities begin to come into existence. Lore and legend are gaining flesh, bone, and blood, yielding things both wondrous and horrible. Magic is powerful, but a limited resource. If the world at large discovers its existence, Equestria will become a target.

Thus, seven friends agree to keep the secret, but some things will not be hidden away.

On a dark night filled with even darker magics, an insane cult attempts to give Nightmare Moon a body and life of her own, utterly separate from Princess Luna. But, when the spell is interrupted by Celestia, something unexpected is created.

Now, a little black alicorn filly named Nyx finds herself living under the care of Twilight Sparkle, only to be haunted by memories and emotions from her past. Is she Nightmare Moon reborn or is she simply a doppelganger with a soul and mind of her own? Can Twilight Sparkle protect Nyx from those who refuse to see past her dragon eyes and black coat?

Or, will Nyx be forced to inherit the sins that may not even be hers and become the greatest evil Equestria has ever known?