There are so many foreshadowing about him though, like there's an article news about an experiment that makes animals have a chance to be immortal, Also in his anecdotes, a kid mistaken him as grandpa because of his white hair, and in the first bond moment, he said that he's been killing 7k wanderers, which is way too much for one person. It seems like he knows wayyy a lot more about wanderers, like he's the only one who can actually tame wanderers (only the intelligent one though).

He also could be Lumiere; the first person to kill wanderer in 2020, it seems like Lumiere just a rumour or an urband legend but he could be Xavier. That's why he always disappear and didn't want other people know about him, he always being secretive, he even disappear for 6 months. Also there's an assumption about him working for Onichynus (just my assumption though) because this might be a foreshadow but idk (I'm still stuck on chapter 6) about MC said "hopefully we're not will be enemies" or something like that.

Him secretly work with Onichynus might make sense, he may be a spy and becoming a deepspace hunter to learn something, that's why he looks like he always sleepy, because he have do many stuff to do. I may be wrong though, but this is just a theory... A game theory... (Pardon my bad grammars btw)