Talk:Stygian/@comment-14703963-20171015045039/@comment-14703963-20171017182446

Well based on what was shown near the end of the Season 7 Finale, it seemed that the Pony of Shadows was actually a seperate entity from Stygian, like a Shadowy Dark Force that played on Stygian's resentment & jealousy towards the Pillars of Ancient Equestria, and convinced Stygian to turn against them, then the Dark Force possessed Stygian thus turning him into the PoS,

And after the Pillars banished the PoS to Limbo, perhaps a small piece of the Shadowy Dark Force managed to get left behind, then later that Dark Force made it's way to Princess Luna, where it played with Luna's resentment & jealousy towards Celestia like it did with Stygian, and once Luna finally gave in & betrayed Celestia, that Dark Force then possessed Luna thus changing her into Nightmare Moon,

So it may be possible that the Pony of Shadows was the Predecessor of Nightmare Moon.