OK, time for some Pepe Silvia nonsense.

Regarding Fandaniel!
There are some hints that something is very, very wrong with him.

One, his actions are antithesis to the Ascians' plans. Their goal was to restore Zodiark to his position as "rightful" ruler of the planet; Fandaniel has no such desire, actually serving as Zenos' accomplice in his efforts to consume his power.

Two, his soul crystal, when picked up in phantom Amaurot, talks about him feeling his soul being twisted and being troubled by it but ultimately accepting it.

Three, while all of the Ascians' glyphs are inverted fragments of their corresponding Ivalician esper's, Fandaniel's... isn't. It's right side up, and appears to be a bit compressed - but more interestingly it's color inverted: the black parts are blank and the clear parts are the ones actually filled in, unlike the rest.

Four, if we assume Zenos has the same measure of control over his Resonance's noncombat functions as Fordola, it's rather plausible that his constant dreams of the Final Days are a result of Fandaniel's presence / influence. Zenos claims to have had the dream for as long as he can remember, but I believe he said it's become more frequent as of late.

Five, he wears the exact opposite colored robes as the other Ascians.

Rewatching the 5.3 scene, he's clearly trying to play to and entertain Zenos, as well as make Zenos believe he has control over him. The plans are all his; he's just using Zenos as a beatstick to get them accomplished, and deferring to him to give the illusion of control to Zenos.

What does this all mean, if anything? Who knows.