I wouldn't completely count out ascian involvement. At the moment it seems like Zero is a pretty heavy-handed reference to Cecil, Golbez is just Golbez, but there is no sign of Zemus/Zeromus quite yet. Golbez mentions to the four elemental archfiends that ascians shared information with him about the Source iirc, so an ascian controlling Golbez could be a reference to Zemus, similarly to how in FF4 Zemus controlled Golbez. But overall Golbez' plan makes... '' sense '' in that he wants to free all the voidsent of the Thirteenth from purgatory, which is not a terrible motive, so it does feel like he has more agency this time around and wouldn't need a Zemus equivalent to control him and feed him potential lies. Yet even if Golbez' motives aren't terrible, his plans are going to mess with the Source and that's most likely in line with what ascians would want. Or is it? I don't think Golbez has any interest in rejoining the shards, and the Thirteenth is still a void that ascians would want to fix before rejoining. So an ascian orchestrating all this doesn't sound too convincing just yet.

Then there's the fact that Zero's name is so close to Zeromus that it doesn't feel like a coincidence, but it might just be a red herring, especially with Zero being a reference to Cecil in specfic. And with that said, I am expecting Zero and Golbez to be brother and sister, just like Cecil and Golbez were brothers in FF4. But how that is going to influence the story going forward, I don't know. Rubicante mentioned that he wonders whether we can essentially '' reach out '' to Golbez, as he hasn't completely gone feral and there might still be some humanity left in him, and perhaps Zero will have much to do with that.