Quote Originally Posted by JonLuso View Post
The Phoenix that materializes in Eorzea is one of aetheric origins that appeared due to a certain person's efforts; it's not the one that appears in Vana'diel or the otherworld of Dissidia which is of a higher plane.

It's, more or less, Eorzea's version of the deity since each of the worlds is in their own dimension. You can only assume, then, that the definitive versions of any such creature is that of Dissidia's.
Honestly are we still dancing around the fact that it's Louisoix? The Flames of Truth CS is even on SE's Youtube channel.

Anyway, he said himself that the Phoenix was an old legend about a bird that was reborn from its own ashes, thus why he picked to become it.

Maybe the diety from Vana'diel once appeared in Eorzea in a time before time and sparked the very legen Louisoix became.