Eiji started out a looong time ago. His original creation was a human pokemon trainer for some freeform gaming I was into on those early chatrooms. His name was stolen from Battle Arena Toshinden, an old 1st gen PS1 game whose character happened to resemble the design I chose. That came and passed and all was good. Shortly thereafter while shooting the breeze out of character in those same roleplaying chats a running joke started concerning living psychotic dolls. Since it was my current character I proposed "Eiji Plushie" and proceeded to joke it up. The joke quickly stuck and I found myself enamoured with this interation, so I kept it, and it quickly became my defacto avatar long after I had stopped running with the joke.
While always a comedic figure, a psychotic one with a perchase for arson and explosions, he was eventually incorporated into a semi-serious array of deities for what I suppose I could call my first campaign setting. While I could wax on and on in detail about that setting, in this place Eiji Plushie was now the progenitor of a whole race of Eiji Plushies, and he was their god-king. Given their association with fire, he was placed as a sun god and took up the title of Solaris Eiji. His background was fleshed and his "Eijilund Plushie" spawn was too. It was proving to be rather popular in that old RP chat I haunted, and I enjoyed many years of quiet internet fame with this.
When I eventually drifted from that chat elsewhere, the name and lore stuck and grew. I am now permenantly in the character of Sol Eiji. The human meat puppet has been abolished, allowing me to escape the confines of his brain and fantasy. Soon I will awaken in your world, my body will be the sun, and I shall swallow all you delicious earth meats. In about 5 billion years. I'm a busy sun god after all.