The Reason Zenos.

[Valic]

He's just a bad apple. His father wasn't exaggerating when he called him a spoiled princeling, that's exactly what he is.

To add on this and prolly going into spoiler territory...

Varis was shocked at the reason for why Zenos killed him. He thought it was to take over the country or something else that this "spoiled princeling" wanted and demanded to have. Thing is, Varis didn't truly understand what Zenos had desired and assumed he's just another garlean royalty after the throne. He isn't and I can easily see why he would want the leader of the Garlean empire dead so that there's no more interference between the WoL and Zenos.

Something else for people to consider.... Yes we liked Emet Selch, yes we liked Gaius... Yes they both have reasonable goals and motivation for why they are what they are and what they do. That's kinda the point of Zenos... He doesn't need a reason to slaughter, he's full of himself on that front already and has been for quite some time considering how bored he was running the empire as is. I my opinion, he's the only character who hasn't had this tragic backstory or some form of redemption arc that involves some fleeting dream of salvation. No, he's worse. He's a psychopath bent on ruining the world's champion and #1 go-to hero to the point of potentially destroying universes just to do it. He's not reasonable like any other villain, he's not negotiable or this character that's been built up with a ton of dialogue from NPC's expression empathy for them. Nidhogg was also a good villain but again, we empathized with all of these villains... Zenos isn't that. He's as Krile said, a ravenous insatiable monster. He will stop at nothing to reach the ultimatum of this story, which is to battle to the death on the brink of existence with the strongest warrior in all of time. To make legend, to feel true struggle, anguish, defeat or victory.

And again I repeat... LOT of FF final bosses are like this. They're not just some entity you negotiate with and all is well or you end up empathizing with them. They're usually the big bad guy that genuinely wants all end to come by their hands and lust for power. Zenos fits that to a T.

Some of you may be complaining "I don't like that" or never felt anything from Zenos upon introduction, but THAT'S THE POINT.... All the WoL from their perspective should know, is they're super effing strong and bordering on immortality. We're not supposed to "like" him or empathize or feel a reason why they're just in their course. They're a villain, they're deranged and fixated on a goal beyond base comprehension of control over empires/countries or simple controversies of man. I'm sure we'll see more backstory in the future but until then, we know enough to understand he's a monster longing for enough power to break the one person he couldn't break and he's willing to go to any length to do this. A far as not enjoying cliche's like the potential of him absorbing Zodiark and us Hydaelyn... Sorry but FF's are cliche. See all of heavensward. I'll admit though I would enjoy a reverse perspective and understanding from Zodiark that perhaps Hydaelyn didn't explain maybe.