Quote Originally Posted by Theodric View Post
Yep. If nothing else, when with the Scions willingly sacrificing themselves only to come back a few minutes later I can't say I care much for the idea that the Ancients should have been content to just sit around inside of Zodiark.
The difficulty there is that the Scions were able to be revived because the purpose of their sacrifice – supplying the aether to make Ultima Thule aetherially tangible enough for us to traverse it – was complete. Their aether was supplanted by Emet and Hyth's creation magic, and so they could safely be returned.

The ancients sacrificed into Zodiark (or equivalent aether, apparently) needed to remain in place until Zodiark's purpose was complete, and aside of any debate into whether they could have or not, the ancients did not achieve that. They may have just intended to leave Zodiark in place permanently if they couldn't figure out the base cause of the Final Days.

I also have to wonder if – given that we know Hydaelyn was powered by the souls as well as corporeal aether of her summoners – this logically must have been happening with Zodiark as well. Are prayers enough to sustain him or is he (by design or necessity) also slowly consuming the souls of the sacrifices to power that planet-wide shield? Would he eventually need more sacrifices to "keep the shield battery charged"?