What formed Eidolon City?
Eidolon City was formed by people in the real world, our world. Only one of these people was aware that Eidolon City would be created. This person is known as The Betrayer, though nobody in Eidolon City has ever heard that name.
It was the Betrayer who took the decision to sacrifice people to create Eidolon City and it was the Betrayer who brought about that sacrifice. Everyone else was an unwilling participant who didn't even know what was happening.
But why did the Betrayer do this? What was the motivation? The motivation was created by the Prophet. You see, sometime in the not too distant future, in the real world, there arose the Prophet, a woman of great strength and vision who preached a message of peace for the world. And, amazingly, her message began to come true. She brought peace to areas of the world where most had almost given up hope of anything but an endless war, she brought harmony to those who before had only known discord and it seemed that, maybe, finally, world peace could be a reality.
There were those who hailed her as a god, and she had plenty of followers all across the globe. One such follower, one of her closest, was the one who would become known as the Betrayer. It was the Betrayer who saw the danger - saw that the world needed balance and that the Prophet was destroying that balance. Peace may be what every same people hoped and prayed for, but actually achieving that would bring about the end of the world.
But the world did not want to heed the warning and the Betrayer found few followers. Far too few to stop the progress towards peace.
The Betrayer found a way to harness a dormant psychic ability which existed in a small percentage of earth's population. It is this dormant ability which meant that the abilities of these people could be harnessed to form a shared illusion - the illusion which is Eidolon City.
Until that connection, these people lived and worked in the world just as you and I do. They had homes and families, hopes and dreams, just like you and me. They knew nothing of the Betrayer's plans - very few, if any, of them would even have heard of the Betrayer.
However, when the Betrayer activated the connection, the result in the real world was that each and every person around the globe who had a psychic ability they didn't even know they had fell into a coma, a persistent vegetative state. But they all remain in a coma, scattered around the world, not in numbers enough to raise an outcry. There was no fuss about it, the world hardly noticed. These people were spread all over, and what was a few thousand people in the grand scheme of things? Anyway, nobody wanted to hear bad news anymore. The coma victims were left, most in hospitals across the globe, some being cared for as best possible by their local communities, or their families. The world went on.
But what of the people? The Betrayer's solution? The balance? What was the Betrayer's plan?
The Betrayer's plan was to use these people, to use their latent abilities to lock them away in a group dream, a city, a place so real that they would 'live' there for the rest of their lives, never knowing that they were only dreaming, never remembering the lives they knew before. And into this dream would be poured all the things that were being stripped from the real world - the pain, the suffering, the evil and corruption. It would all be found here, in one way or another: in Eidolon City.