[Spoilers] Why Zenos is the most important character moving forward

[LineageRazor]

Zenos undergoes an arc from being directionless and desperately seeking purpose for himself to finding that purpose in an opponent capable of overcoming him. Someone who can truly challenge him and make him strive. He went from valuing no one to valuing someone for the role they fulfill in his life. It's a very, very simple arc, which fits with the fact that he has huge elements of human identity missing from his personal development. This is not missing in the sense of "writers couldn't be bothered to fill it in" but in the sense of "some people lack the ability to conceptualize X and have to fill and adapt to that in other ways".

I wouldn't say Zenos was at all directionless. He knew all along EXACTLY what he wanted. Dialogue in the game indicates that this was exactly why he appointed Yotsuyu to Doma, why unleashed the Skulls on Ala Mhigo. He oppressed the people in order to try to dig out someone willing to fight back, to force the emergence of a hero. The Hunt long predated the Warrior of Light. His entire life was a fruitless search for a worthy opponent. Directionless implies that he did not know what he wanted, but he very much did.

Really, the extent of his character arc was going from "looking for a worthy opponent" to "FOUND a worthy opponent". In fairness, this DID result in a radical policy change for the guy, wherein he lost all interest in paying lip service to Garlean high command and was far less interested in prodding the downtrodden in the hopes that one would rise up and try to bite him.

The moment Zenos became Emperor, is the moment all his failings as a leader and administrator destroy his ability to execute any plans to confront the Warrior of Light without it contradicting his character or common sense. Heck, using Black Rose would contricit his character because he wants to fight.

I don't think Zenos's goal was to become emperor, nor do I think he HAS become Emperor. His goal was to stop his father from unleashing the Black Rose and possibly killing Zenos's quarry, not to take the throne himself. It's also very unclear that Garlean rules of succession would just hand the throne over to the guy - there was a civil war the last time an emperor died, after all.

Now that Varis is dead (if he's dead), that goal has likely succeeded. I doubt Zenos cares at all about what becomes of Garlemald at this point, whether they declare a new leader or destroy themselves through civil war. In fact, I'd guess he's all about the civil war - with no clear leader, the Garleans would be focused on themselves and far less likely to deploy chemical weaponry elsewhere.