[Spoilers] Death and reincarnation

[Absimiliard]

For the record, I think Zodiark's evil, mainly for the 3rd sacrifice plan. I think we've seen enough to know that sacrificing others' aether to bring back a dead person never works out how the summoner intends. And yet that's the ultimate goal and motivation behind the rejoining and its associated atrocities: to get Zodiark whole again so he can be fed that aether and bring back the dead Amaurotines. But, as I said, even if he was whole, everything we have ever seen tells us that the plan won't work. Zodiark would know his own capabilities, but he's not dissuaded the Ascians in the least. Why? B/c the plan feeds him aether and that's what he's interested in.

Zodiark is not Ramuh or Titan, simply interested in protecting his charges and being otherwise passive in nature. He covets power, exactly how the Word of the Mother described him. And the Ascians would see it, too, if they weren't tempered.

The failed instances of resurrection we've been shown have occurred after the soul had returned to the lifestream. We can't even be sure bringing back the dead won't work in this case since their souls are, at least according to Emet-Selch (and his ability to draw power from them during the fight against him), still completely intact within Zodiark. Zodiark proved capable of creating life seemingly from nothing (but presumably by converting aether into matter the way Ancient creation magics did) to restore a dying world. If he could do all that - even creating new souls in the process, it would seem - then what's to stop him from being able to give fully intact souls new physical bodies to inhabit?

Also, who says Zodiark is the one calling the shots? All we know of him so far is that he does what he is summoned to do. The Ascians imply that he's been completely dormant ever since the sundering, meaning he likely has zero ability to influence their actions. We don't even know for a fact that he stuck around after his second summoning. What we do know is that tempering is not necessarily a voluntary action on the part of primals. Even Ramuh, who opposes the practice, found that he could not prevent it from happening. Zodiark could well have tempered them without actually meaning to.

The Word of the Mother is essentially just Hydaelyn using someone as a mouthpiece. They speak from Hydaelyn's perspective even when she isn't directly controlling them. Anything Hydaelyn or her Word say about Zodiark must be considered suspect due to the obvious bias at play. It doesn't help that Hydaelyn has lied to us several times now, either. Mind you I'm not saying she's evil, but I definitely don't just blindly subscribe to the whole "big good" vibe she tries to present herself as having.