So far I have only one theory for FFX.
Let me introduce it.
I always wondered how Bevele´s machines can stand a chance against Zanarkand´s aeons.
During the game Yuna´s aeons seems to easily wipe out even the strongest machines.
So it´s difficult to believe what happened on the Bevelle/Zanarkand war.
Unless of course it wasn´t machines which attacked Zanarkand but "machines".
In fact Bevelle was destroyed by "machines".It was originally the city over the moonflow.
Afterwards "Bevelle" appears as the current game Bevelle.
The various machines around the world were destroyed by "machines" even though Zanarkanders and recent Bevelle religious people would erroneously think they were destroyed by Sin.
Now,some of the "Bevelle" "maesters" deceive people in various matters including making them think that the "Bevelle" they live is the true Bevelle city.
I think only Mica and maybe Kinoc are "maesters".The other ones are maesters.
There is a strong possibility that Seymour is also a "maester".
But never Kelk.
I will give you time to think about this theory and the game.Maybe you will get what I mean by the words in commas.