Finally, an in-game glimpse of my boy! Looks to me like what we’re
seeing is a mere concept outline of him, albeit with modifications to what was seen in the Amano art. If his “rebirth” (re-summoning?) is blocked by the chains Hydaelyn bound him with, and these act similarly to the seal in Silvertear Lake, it might not be inconsistent with Fandaniel’s testimony of him being dormant but with a rage – because Primals return to the Aetherial Sea (or in this case, maybe a cordoned off section of it in his case, within the moon) upon defeat, so it is perhaps that aether-form manifestation Fandaniel is referring to. The entreaty to him in the
French version has me thinking, he is being summoned anew, and his purpose re-oriented to fit Fandaniel’s designs. If he (possibly Hydaelyn too) are going to draw inspiration from Necron, an excellent way to replicate the idea in XIV is to have the summoner's intentions affect the primal summoning - a nihilistically minded summoner would thus imprint on the primal much as Kuja influenced Necron's views. I don't think he has any intention to serve or revive him, so much as use him (and Hydaelyn) as fuel for whatever scheme he is concocting, be it in service to some otherworldly being, or not. Particularly if Zodiark's (and Hydaelyn's) removal would somehow unravel the new laws he set in motion for the star - a line in the French trailer, possibly attributable to Thancred, indicates this might play into it:
"But if the laws of nature are lost, no one will survive."
It’s still my expectation that the trial won’t be a straight up Zodiark fight, and that any actual fight will be reserved for Pandaemonium, on a what-if basis, but we’ll see.