Quote Originally Posted by LisSquid View Post
From what was implied slightly (and we probably could have understood more if a certain zone wasn't 90% devoted to fan service) is that the influence of Meteion was suggesting the populace sacrifice half of themselves - again and again - to sustain Zodiark. While we see that Zodiark was holding it back just fine without more sacrifices, I sort of assumed it was that it was the direct result of the Song's influence causing people to double down until no one was left.

SE didn't clarify or justify it, but that was my final interpretation of the cinematic. Why Venat wasn't influenced and why the Unsundered wanted to continue the cycle (sacrifice all those on the shards) I have no idea.
that doesn't shake considering Zodiark specifically shielded the star from meteion.
Hence the "at last" when Big Z bit it.
So all the sacrifice idea are all their own.