This is late re: nabatean blood color discussion but figured it might be a nice change of pace + an excuse for happy Cyril content.
First off the Blue Sea Star is 青海の星 in Japanese (Aoi Umi no Hoshi) so that isn't surprising, excpt ive seen JP fans describe Rhea's blood at the end of CF with 青 too as it can mean both green and blue in Japanese.
Then there's Cyril's prayer in the explore chapter after Jeralt dies. He says it's a prayer of mourning from the Church of Seiros Rhea taught him and it ends with: "Receive them into your blue blood. Receive them into a twinkling star."
Checked the script and it is indeed 青き血 so blue OR green blood. I'm definitely thinking too hard about this compared to what the writers intended but the idea the Goddess herself and her blood is blue/green and that has holy connotations... idk I think it's interesting.
This is very interesting!
I thought Cyril's prayer about the "blue blood" meant the sea being the "blue blood" of the star Sothis came from, but it would also make sense that "blue blood" could be literal blood, so Sothis's blood is blue, just like her children in their "true/truest" forms (even if I hate the notion of a "true form", because I always thought Nabateans were more like Laguz and both forms are "true forms", unlike Manaketes!).
But prayer-wise it works!
Maybe Rhea thus had to lie about the "Red Canyon", since saying "Blue/Green Canyon" wouldn't be as impactful, for humans who wouldn't understand Nabatean blood is Blue/Green, to still convey the Tragedy somehow to humans, without revealing the beings there weren't humans (thus didn't have red blood).
Still, their blood is "red" in their humanoid form - we see an injured Rhea having red blood on her iirc, and Balthus mentions drinking a red beverage to get a crest.
Or, Nemesis fought some Nabateans who transformed, but slaughtered a majority of non transformed Nabateans in Zanado (thus the canyon was a giant patchwork with more red than blue/green?) and by transforming, Nabateans get "closer" to Sothis, aka the divine, who herself had to take a humanoid shape to get closer and interact with the humans who lived in Fodlan when she appeared?
It really pisses me how the devs took time to write some stuff here'n'there like this, but never bothered connecting the dots, because we could have had a fascinating background !
At least it makes for fun hc/theories!