I have a theory!!!

its about the season 7 finale so if you havent watched it, then dont open this post.

first, i want to say how much i loved the more subtle build-up as a posed to the rainbow connections arc. the stories werent the main focus of the episodes, more side-plots that moved the main plot along. i also enjoyed recognizing the ponies and artifacts from previous episodes, and the possibility that we could have new main characters and worldbuilding!!!!!!!! anyway, not the point, my theory is that the shadow power that transformed Stygian into the shadow pony is the same power that transformed luna into nightmare moon.
Here are my reasons:
1. they both felt abandoned pre-tranformation
2. they both tranformed into darkness themed villians
3. they both got reformed using the elements of harmony, albeit in different ways
4. both were banished for 1000 years
thats all i have to say, your thoughts? id love to hear from peoples.