I would consider the FF4 storyline on this:
Long version short, an ancient evil (Zemus) on the moon appears in the last act and had been manipulating the big bad in the game up to that point. The original big bad (Golbez) actually joined the hero’s side at the end to fight the moon entity.
So, I suppose that kind of storyline is possible, and I’m not even sure if Zenos would be the “Golbez” or the “Zemus” in this line..but hey, could happen. The names Zemus and Zenos are awefully similar...
Also it would not surprise me if Fandaniel is being controlled by some entity (as in “a branded Ascian”)