The Rejoining (Spoilers for EVERYTHING up to 2.55, welcome to Lore)

[Nalien]

Ever since T5 I have had the opinion that Hydaelyn is, effectively, just a really really big Primal. The Mother Crystal we (used to) communicate with? Hydaelyn Prime. The planet? A Primal large enough to have ecosystems growing on it, all life on it technically a part of it. Primals? Effectively cancerous tumors.

Zodiark, then, I would imagine is much the same. Except dead. The Ascians are attempting to sacrifice our planet to have theirs reborn. Whatever insane scenario lead to the death of Zodiark gave birth to Hydaelyn (or perhaps something else which eventually gave birth to Hydaelyn), however a fraction of their world was saved, hence the Rejoining; The Aether which makes up Hydaelyn was originally Zodiark. To restore their world is to rejoin it with "his" Aether.

Ready for this to get crazy? I'm certainly tired enough for a little crazy; Zodiark is Final Fantasy XII, or close enough. All the Ivalice connections with the Ascians a result of that. The original Final Fantasy gave us a never ending cycle to break. When we defeated Chaos, that world was free of Garlands' cycle and free to advance into the future. That future lead to that worlds death, but the birth of Final Fantasy IIs world. The "aether" which made up Final Fantasy was recycled to create Final Fantasy II, and so on for every "main" game in the franchise. Each game has no direct link, but they're all part of the same canon. Final Fantasy XIIs world eventually died, it's "aether" then going on to create Final Fantasy XIII, but something of Final Fantasy XII left this cycle, surviving outside it. Final Fantasy XIII suffered as a result, as it received less "aether" than the previous titles. Final Fantasy XIV also suffered due to this, hence its initial release. What caused Final Fantasy XIV to pick itself back up and become a huge success? Oh right, the Ascians Rejoining attempt. Long lost "aether" attempting to be rejoined to the main franchise... Are the Ascians evil? Not at all. They're the key Final Fantasy element many had complained has been missing from the franchise in recent years. Ironic, given their Final Fantasy XII connections. Obviously we shouldn't let them recreate Final Fantasy XII (Oh hell no, we should totally be letting them make a Final Fantasy XII HD rerelease!), but we should certainly try to get that "aether" back! Currently Hydaelyn is losing the battle and weakening as the Ascians look set to succeed at using Hydaelyn to rebuild Zodiark, through the course of Final Fantasy XIV I imagine we'll be gradually turning the tables on them and instead having Hydaelyn absorb Zodiark to make the franchise whole again, so the next world can be a success when this one eventually dies.

<Looks at Final Fantasy XV>

Well, we tried... I kid of course, I hope...