who are mimicka and the eyes?
mimicka is the entity that created and (somewhat) manages the eyes. they don't clarify their origins, but they live in the eyespace. they have the ability to collect whatever makes a person themselves (soul, aura, spirit, whatever it is, it depends on the universe but for simplicity i'll call it their being) and turn them into an eyelet. it's not a literal eyelet, but instead is more like an amulet that protects and stores their being. once a person gets one, they're considered one of the eyes.
the eyes are people under mimicka with an eyelet. they became that way with an agreement with mimicka, granting themselves a wish and then mimicka takes their being and puts it into an eyelet. the eyes can't die unless something damages their being, which is why the eyelet exists to protect it. or if mimicka decides to kill them. mimicka actually has a decent amount of control over the eyes, being able to see them from afar (depending on the circumstance) and being able to control their bodies (the closer the eyelet is, the more control they can have). of course, mimicka didn't disclose this information at first.