I'm pretty sure the Lucavi are actually political conspirators from the distant past who used the Zodiac Stones and the bodily forms of the demons/espers in order to attain a sort of pseudo immortality such that they might continue to work their desires in the world, making the whole demon thing an actual extension of the political intrigue the rest of the game is built on, and a natural result of of a world setting in which magic is a real thing?
Consider: the plot of Vagrant Story as being somewhat like this with all the fat trimmed away
Consider: the plot of Vagrant Story as being somewhat like this with all the fat trimmed away