Where the “Seiros fought against the Agarthians” came from?
I was re-reading VW’s script and Rhea goes, during her final infodump :
The progenitor god and her children shared knowledge and skills with the people of the land. Together, they built a prosperous civilization. But the humans turned their backs on the teachings of the progenitor god and engaged in senseless wars. Eventually people began to think of themselves as gods and challenged the progenitor god herself to battle. The land was scorched in the war that ensured and the majority of humans were annihilated. I believe that those who slither in the dark are the descendants of those who retreated beneath the ground during that time
Deconstructing it we’ve got :
Sothis and her lizards share “knowledge” with the Fodlan natives
Humans started a crapton of wars
Eventually, they turned against Sothis, challenging “the progenitor god herself to battle”
Scorched Fodan ensued, and a majority of humans died
Descendants of humans became mole people
(which raises the WTF is Raphael, he is one of the mole people who migrated on the surface, or every survivor went underground but after some generations some wanted to live on the surface?)
Thales’n’co engaged against Sothis personaly, thinking they could take her on. But he also has a grudge against all Nabateans, identifying them based on their pointy ears, green eyes and hair.
So I doubt Sothis was the only one who fought, maybe some of her children helped in the fight (Rhea and Seteth?) ; I doubt Flayn took any part in it, since the only great war she can remembers is the War of Heroes, iirc.
Ultimately, per Rhea’s words :
It took the progenitor god an astonishing amount of time to revive the ravaged world. But eventually, the continent found peace again, and the progenitor god, having fulfilled her duty, fell into a long slumber in the Holy Tomb. The children who stayed behind built a settlement in Zanado to protect the Holy Tomb as they quietly lived out their lives
Rhea, a being who could live for more than 1000 years says that it took, in her eyes an “astonishing amount of time” to Sothis to revive the world, and then, the “continent found peace again” or whatever that means (Agarthians were playing wack-a-mole with Sothis and sometimes launching missiles from their underground city while she’d be busy reconstructing the world?).
After the world was back, and the agarthians stopped playing whack-a-mole, Sothis fell asleep.
But the children built Zanado after their mom went to sleep, which would somehow clash with Sothis’ own memories, saying she remembered Zanado - unless she woke up for short periods of time to see if everything was alright, before falling asleep again.
The game gives us clues about Rhea (and Seteth) not having been a part of the mole people suppression squad. In the Shambala Chapter, SS version, they’re both curious and don’t know what the Titanus are:
Thales: Now is the time. Remove the binding spell of Titanus. Let their metal bodies be drenched in blood!
Seteth: What is that?!
Rhea: Demonic Beasts… No, I think not. They appear to have no will of their own. Someone must be controlling them.
In the Shambala Chapter, VW edition, she reveals some interesting stuff about the missiles :
Rhea: Once, a very long time ago, a massive ball of light fell upon this monastery. However, that light mysteriously changed course in mid-air and landed in Ailell instead.
Leonie: Ailell, the Valley of Torment... So that's what the wreckage of those javelins of light looks like.
Rhea: The Holy Tomb is not only the location of the progenitor god's eternal slumber, but also a sacred vessel for a power that repels evil. Supposedly, the progenitor god built the Holy Tomb herself to protect her children from the evil light.
(meaning that Ailell’s bombing happened after the birth of Garreg Mach?)
Rhea can only recall the Ailell incident, talking about those javelins of light. Also, she supposes Sothis built the Holy Tomb as a nuclear shelter, she doesn’t affirm it. Granted, this is pre-dubstep Rhea, so she isn’t on death’s door and she might be hiding/twisting some intel...
Meaning, if we believe her, that there have been many instances where the Agarthians launched their missiles, the first time, Sothis would have built/put a ward on the Holy Tomb to protect the Nabateans, the second time, it happened in Ailell. The first time, Rhea wasn’t here or might have been too young to understand and know the true reason why Sothis built the Holy Tomb.
Adding to the previous list :
3.5 : While humans were challenging Sothis, she built the Holy Tomb as a shelter against the new missiles humans developped
So - assuming Agartha used Titanus and Javelins of Light during their war against Sothis - it is suggested that Rhea and Seteth didn’t take part in this war, because both don’t know what Titanus are and Rhea, who only remembers Ailell, isn’t sure about the Holy Tomb’s function as an atomic shelter.
I may be wrong, but we have more clues supporting the “Rhea’n’Cichol = babies do not send them to war against arrogant humans” than the “Rhea was part of the Agarthian suppression squad with her bros”.