So... there's a fabled T12 cutscene floating around on the interwebs that explains pretty much everything regarding the events of 1.0 but SE keeps taking it down whenever anyone posts it so I'm not gonna give any links.
I don't see any reason why we wouldn't be able to discuss it, however, so I'll outline the events below and what I feel are the main revelations from the scene.
Needless to say there are huge spoilers here so stop reading now if you don't want this spoiled.
The scene starts within the flash of white light that everyone across Eorzea claims the Warriors of Light and Bahamut vanished into. The truth of the scenario is that The Twelve had appeared before Louisoix, calling him into another dimension. Recall that the swords the Archons summoned to imprison Bahamut had shattered. These were different; not only that, they were made of solid crystal identical in appearance to Hydaelyn.
So first point: The Twelve are real.
Louisoix looks up at the crystals and opens his palm as though the Twelve are giving him something. He then closes his palm and starts to grow in power. The white light vanishes and he is back at Cartenau standing beneath Bahamut's megaflare exactly as it was in the final seconds of the End of an Era video. He glances down sadly at Bravura impaled in the ground before him then erupts in white light and flies into the megaflare, stopping its expansion with a great seal identical in appearance to the one above the arch at the Sanctum of the Twelve.
Second point: I think it's fairly safe to assume that The Twelve gave Louisoix their aether and essentially turned him into a demi-god.
A battle ensues between him and Bahamut with Louisoix's body beginning to crack and burn with aether the harder he fights. Louisoix eventually overpowers Bahamut and flies right through his chest, leaving a gaping hole. Louisoix's body then burns up entirely and dissipates into pure aether. Bahamut, meanwhile, turns to crystal and shatters with an explosion that entirely decimates Cartenau.
In the aftermath pure blue aether rains down on Eorzea (presumably from the Twelve and Louisoix) which explains how the land was able to recover so quickly from the devastation.
Third point (sort of): Considering that the boss of T12 is Louisoix having turned into Phoenix (and I mean turned into, not summoned, Alphinaud is quite clear about this and it's not the same as what Iceheart did) we may have more of an understanding of what a primal actually is. Louisoix was not tempered by bahamut, he took on no draconic features like Nael did and says quite clearly in the scenes that he defends Bahamut of his own will. He instead channeled so much aether his physical form was entirely consumed and 'transcended the limits of Man's existence' (again, Alphinaud's words). Is a primal the husk of a person that essentially became pure aether?
Fourth point: Bahamut's shattered remains frozen in crystal around the coil areas were clearly the remnants of the Bahamut that Louisoix killed. The Bahamut being summoned by the fragments of Dalamud (using the extracted prayers of all the Meracydian dragons in stasis pods around the Final Coil) was a new Bahamut.
Fifth Point: We have confirmation that Bahamut is the primal of the dragons. The Meracydians summoned him to defend against the Allagan invasion as per Louisoix's very own words.
There are further revelations from T13 but I won't go into them here. Hopefully since this is just a discussion thread and not a link to any of the actual videos the mods won't take this down. That is what this lore forum is for after all...
So, has anyone interpreted any of this differently to me? Curious to hear other people's thoughts.