Hello! I'd like to receive some information, possibly without spoilers because I just started Endwalker.

Can anybody remind me what exactly happened to a few characters?
For instance Zenos. He was the son of the previous king of Garlemald, heir to the throne and quite capable with weapon fighting. He was in charge of Ala Mihgo campaign and fought (and got defeated) by our hero over and over, even after "merging" with Shinryu.
He died and and his body got "invaded" by an Ascian (was it Elidibus or Emet-Selch?).

But for some reason (?) Zenos' soul survived, got into a dead garle soldier body, returned to the capital, defeated his own ascian-controlled body and regained control.
After that he killed his own father (but why?) and is attempting to destroy all of Garlemald and eventually the source (why?)

An Ascian, Fandaniel, somehow becomes his servant (why?) using the body of Asahi sas Brutus, and he too wants to destroy the source (why?!)


I'm a bit confused on these characters' motivations. They just seem to be evil for the sake of being evil? Or what? I must be missing something.