Quote Originally Posted by Quor View Post
Where did you see that information on Eden?
The raid storyline identified Eden as the Original Sin Eater as well as the origin and propagator of the Flood itself. The Akadaemia Anyder Notes towards the end of the dungeon talk about how they began development of potent Guardians to stand up against the oncoming calamity. Considering how the calamity function as it was shown to us then Eden's design makes it perfect for combating the Calamity, its ability to slow Aether to the point of stasis allows it to eliminate out of control creation magic in a large zone as well as basically kill off any fear created creatures. Considering also that the last boss of the Dungeon is another Guardian Force from FF8 just like Eden is it lines up.

How it wound up on the First is unknown. However given that the First was heavily aspected towards light already it would be safe to presume that the First was aspected towards light so much mostly because Eden was slumbering on that shard.