Cio’s design here is a bit similar to the very first White Chain design, in that her helm covers/closes both her eyes. Given how symbolic that was for White Chain, and that White Chain’s eyes opened as her mind opened up, it’s also likely symbolic here
Cio’s design also, like White Chain’s, has a design on the forehead that could hold a stone. Granted, she had one before, an ordinary one–but I wonder if she might end up getting Gog’s. That would make both White Chain and Cio hold the keys that are possibly closest to their natures as angel and devil…or at least, opposites to one another
Cio’s design here is like a preying mantis, and as we know, they eat their mates
Cio’s teeth here are more purple than blue, as if they’re chips of ebon devil
Thoughts: