This idea of a fallen-from-grace character is a common motif when it comes to Miyazaki, but it's so effective every time and always adds a dimension to the games' lore. To this day, I think Gehrman in Bloodborne is my favourite boss fight because it's simultaneously a test of everything you've grown into over the course of the game yourself, and also the conclusion of this man's painful, long and tragic existence
There are definitely a few exceptions. Pontiff Sulyvahn (DS3) comes to mind as one, it's possible that Godrick in ER is also although we'll need to uncover more lore still. Byrgenwerth (Bloodborne) as an institution definitely. The motif of evil with Miyazaki often seems to be the institutional evil that affects the world, and very occasionally specific individuals in those institutions
