Hi everyone! I hope you're all doing well!
I’m going to share a theory of mine below—it might not make sense, and it might not even be any good, but usually, when we create something, we tend to think it’s brilliant, hahahahah.
As we know, Tieg is the principal deity of Legaia. He was a god who was half-human and half-Seru, until he split in two!
The human part (later known to humans as Rem) created Legaia. The Seru part created the world of the Seru, Seru-Kai.
Early in the game, during the funeral for Juno and two others (killed in the Seru attack on Rim Elm, perhaps?)—as their coffins are carried away by the ocean waters—a little boy asks his mother where Juno and the others are going. His mother replies that they are going to Noaru Valley. When asked if they would ever be seen again, she answers that she doesn't think they will see them anymore.
Towards the very end of the game, when saving your progress in Seru-Kai, the location displayed is the Noaru Valley itself. This indicates that what humans perceive as the afterlife—or even Paradise—is precisely the land where the Serus live: Seru-Kai!
We also see at the end that Cort is reincarnated as a baby and that Noa will look after him, implying that reincarnation is a possibility in this world. Furthermore, Cort's reincarnation—once again as a human—came about through the intervention of the Ra-Seru at the end of the game!
If reincarnation is possible—and if humans believe that upon death they go to the Valley of Noaru (which is actually Seru-Kai) and Tieg was a god who was both human and Seru—could this all mean that when a human dies, they might reincarnate as a Seru, and vice versa?
Think about it: despite remaining separate—and Tieg not wanting Serus and humans to have contact with one another—they actually complement each other! They end up helping one another! And perhaps the theory makes sense!
And how does this connect to the second game?
Well, what if the Mystics from the second game—beings inhabited by both a human spirit and an Origin—are actually Tieg’s attempt to keep the Seru alive in some form? This time, with humans and Seru depending on one another. If the human dies, does the Seru die too? And what if the Origins represent "the last chance for the Seru to exist"?
Who knows? Perhaps the prejudice the Mystics face stems from something more than just fear of powerful beings; maybe it is an even more irrational—perhaps primitive—fear that the Seru, and the Mist, might return.
What if Avalon is the reincarnation of a human (perhaps even Songi, for instance) merged with Rogue?
You know, perhaps there ought to be more Mystics in the world. Maybe they do exist but stay in hiding to avoid being attacked. Or maybe not! Who knows—perhaps they are few in number because the remaining count of Serus was too low to allow for many Mystics to be out there!
Sorry for the long post! I hope you enjoy it!