At one point I speculated that Fandaniel's throwaway comment about Zenos being a case where Emet-Selch "finally succeeded" was about Zenos' corporeal aether being as dense as an Ancients'. Not his soul, but his body at least being 2x as dense as the average Source inhabitant (and 14x as anyone from a Shard).
One of the big reasons for the Sundering was that extremely aether-dense people can't interact directly with Dynamis. You can hear Meteion bc your aether is so thin. People turn into monsters bc Dynamis overwhelms and consumes their Aether.
What if Zenos cannot directly interact with Dynamis. At all.
What if THAT'S why everything seems dull and boring to him? There's a whole spectrum of emotion & feeling that he straight up can't feel because his booty too fat his corporeal aether is too thick. But he's still a sundered soul, so part of him still needs Dynamis to feel connected to other people (unlike the Ancients who seem fine?). But his corporeal aether blocks it. The same way that Zodiark's shield kept us from hearing the Endsinger for all those centuries (& by extension the whole universe really), Zenos' thicc aether literally prevents him from feeling connection to others.
This explains why he so easily no-sold the WoL. In addition to supernaturally thick aether, he's also mostly immune to our Power of Friendship crap.
Because obviously the Ancients still weren't immune to the Endsinger, her effect was just different. They didn't turn into monsters, but their imaginations turned on them, causing their creation magic to manifest ravenous nightmares. In the same way, some part of the WoL's Dynamis was so potent that it broke through. And that's why he became so completely addicted to us. We're literally the only person with powerful enough Dynamis that he can feel any connection at all.
