I like him because his motivations are simple, but it leaves the door open for further depth in the character, especially with how Endwalker panned out and how even Zenos has to evaluate his goals and how to proceed with them.
I think his assessment of who the Warrior of Light is fits perfectly with how I perceive my own WoL, and his relationship with the WoL becomes intriguing because it's two very opposite people with completely different values and morals, but there is this sole unique reason that connects them deeply, even more so than many of WoL's own friends.

Plus he is a hottie and this relationship they share can easily be written into something romantic, albeit quite toxic perhaps. That's cool too.