Originally Posted by
Jandor
Zodiark doesn't seem to have much, if any, will of His own. Without a 'heart' He seems content to just chill out in the primal equivalent of sleep mode. Also, if I recall correctly, the sacrifice plan was being formulated while Elidibus was still in Zodiark, the arguments about going ahead with it are what caused him to withdraw himself from Zodiark.
Now I am kind of suspicious that Elidibus reappearance suddenly quells the majority of the dissent, but I don't really doubt that Zodiark would have held up His end of the bargain to the best of His ability. I would probably be more suspicous that it's just a ploy for more aether if Zodiark was the only Ancient primal, but Hydaelyn never seems particularly aether hungry either, and they're almost certainly more similar to each other than they are to modern primals.