This one is half a little headcanon of mine and half a fact about this AU~

There is a "villain" that I had not talked about much before, the Tantabus. The Tantabus was created from the remains of Nightmare Moon influence in Luna's body and tormented the princess in her dreams, about the outcome she thought she deserved. Since this AU takes place in the finale of season 4, Luna never forgave herself, and the Tantabus remained in her body when Nightmare Moon took it again. (note, in this AU Nightmare Moon only has Luna's body, Luna's soul is not attached to it)

Nightmare Moon "passed on" the Tantabus to her daughters, Spectra and Astral. They have it since they were born (or created, since they were the results of magical pregnancy spells rather than the conventional method). They have a very watered down dream walking power.