On the Illborn, I was thinking, the people who show up in the Astral Influx are these:
Ciro, Riltia, Al, Cherish, Proxxy.
Ciro is main character.
Riltia was not available while in her Yandere form.
Al is neither Illborn nor Sibling.
Cherish is same.
Proxxy is a confirmed Sibling.
Characters not available that (maybe) should have been:
Wilford, Chief, Mili, Cool Crab, Slog.
Clearly, the first three were never part of the party, but Chief is a confirmed Illborn, and Wilford and Mili are unknown.(And we'll never find out, since Wilford's taking an acid bath and Mili's... you know)
Cool Crab is a confirmed Illborn.
Slog is a confirmed Illborn.
What this seems to suggest is that Illborn cannot be selected by the Astral Influx, even if they can speak(Cool Crab) or have a place in the shipping chart (Slog)
Also, Cool Crab placed himself into the Illborn Exchange, which means that while the Astral Influx can't take Illborn, the exchange picks them up, but can't take a non-Illborn, but we still need to figure out how that works.
It's called an Illborn Exchange, but what is it exchanging? It can't be the Illborn themselves, because Cool Crab went into the larger box, and there's only one of those.
So we have the Astral Influx, which controls the selected character, and the Illborn Exchange, which affects Illborn in some way....
So.... what does Proxxy's do?
I think that once we figure that out we'll have a better understanding of thier importance.
Now, back to Riltia not being able to be selected while in Yandere form, since the Astral Influx doesn't seem to process Illborn, it seems to me that Riltia actually became an Illborn herself during her transformation, which would indicate that being "Illborn" is not what something nesasarely is, but rather, that being "Illborn" is more of a state of being, that can change. Maybe Chief wasn't always an Illborn? Maybe he was originally a free soul like Al, which begs the question of what happened to Chief?
As for Proxxy's odd color on the Astral Influx, if the Astral Influx and Illborn Exchange are both soul stones or whatever, then how can it choose someone who already has their own soulstone? In fact, FFS stated during the interlude of Cain that he didn't want to shift characters, "without the Astral Influx", but how would we shift to Cain if we never met him? He doesn't show up as an option, and in that case, how would we switch back? And would his portrait have a green color over it? If that's the case, then why doesn't Riltia have a grey color over her? Why doesn't Ciro have one?
Why does Cain's Soulstone have power of the Illborn? Maybe he was a force in creating them? Maybe he's an Illborn himself, along with being a sibling, which would explain why he never showed up in the Astral Influx, but, if he never showed up in the astral influx, because of him having an Illborn quality, then how did the Narritive Control select him? If Cain really is an Illborn, than we can probably safely assume that he became one through the murder of his siblings, in which case, how long does Al have before he become one through his acts?