What is an Eidolon?

Having seen Lord Ehses' demons, when my mother passed, I never once doubted the other's existence after that. All I needed was that faceless mass staring into my eyes like it was judging my soul to tell me it belonged to an Eidolon. I still wonder if it found me wanting or not.
— Human Farmer

Created by the Unknown Being, Eidolons, is what he would call his true children. While none of them looked alike he was infatuated with each one as he gave them life and purpose. Trying to give them equal standing and equal holding but finding it difficult to manage like any parent. Giving life to seven girls and five males though the people of Eiria often assume the gender of some Eidolons. Giving them powers over his world to see what would unfold for his own entertainment. Making it where they could live for eons and only die by murder even if they had no knowledge of this part. Each Eidolon is given a domain over the realm of Eiria. Their magical talents in relation to their given realms, along with what they do and influence within the mortal realm. Often either making copies or the more favored way of sending proxies to deal with things on the mortal plane. Though there are times in which a mortal may catch the fancy of an Eidolon or in some cases worst, two Eidolons.

Fiends & Archfiends

Fiends

Creations of their Eidolon masters, they are often on the mortal plane of Eiria. Often used as the messagers, eyes, and ears of their master. Often created to their master's liking or image they associate with. While there could be hundreds of them they are mostly benign and only follow the orders of their master.

Archfiends

While not any more powerful or different from fiends, Archfiends tend to be like a favored fiend, often older than most fiends but not always. It's like picking a favorite child. Often these are known by the common person of Eiria or at least rumors of what they look like and who they answer to.