Talk:Princess Luna/@comment-32480615-20181017175609/@comment-7345250-20181017193950

It really depends on the material you're looking at.

Multiple comic sources have established that Princess Luna was corrupted by an extrinsic manipulator. However, the show has neglected to corroborate the existence of these "Nightmare forces" and retconned what connections Luna did have to such personae as the Pony of Shadows.

In summary, there is plenty of official material that says something took over, but the all-important show has not been consistent with that lore.