Garland, that is.

Apparently he's from another world, he's Kuja's boss, and he has ties to Zidane. (Guessing Zidane was sent to this world for the same reason as Kuja but he lost his memory, though I can't recall how much the game has gone into Zidane's backstory)

I just defeated a book in order to get running shoes.

Garland just nuked Alexandria - that escalated quickly.