Spoken from Heidi:
Once, there was an Arceus that was full of love. As her world developed, she’s grown to care for all things. She loved the Legendary Pokémon that were her children. She cared for the various other Pokémon that called her land their home. She adored the humans that roamed the fields and learned of the environment around her. She wished nothing but to continue to watch on as her world grew into a utopia… a place where people and Pokémon could live together in harmony.
Over time, she would work to make that a reality. She would teach her Legendary Pokémon love and kindness… to work together for the benefit of the world and the constituents under them. She would adopt a Pokémon or two to learn more about them. She would even occasionally descend into the mortal realm to make friends of the humans, so that she may love and be loved in return.
It was then her final act of love that would change everything.
The Arceus could not contain her love for any longer. She loved her children, the Pokémon, and the humans too much to stay isolated. So, one day, she used her Hall of Origin to erect a great city complete with parks, shops, services, and even a gym, all centered around a giant watchtower that was her living quarters. She then actively invited humanity to come live with her… to live in the new city and learn of and live alongside her and her children. Many people moved in the new land, taking their cultures, their friends, their family, and their beliefs with them. The City had its growing pains in the beginning; however, it would quickly become the grandest place that the world has ever seen… and would become her magnum opus.
However, this came with a price.
As humans came to know her, they would grow discontent with her. The humans did not care for her as she did for them. They rose against her, demanding more and more of her live while giving less and less in return. She would do everything that she could to satisfy them, but it was not enough. Over time, her heart hardened as her greatest act of love became the vector of humanity’s biggest source of greed.
In 50 years, the great city would fall into disarray.
In 100, the world would follow.
The once-loving Arceus had enough of her internal torment and waged war against humanity. She casted Judgment against the land and throughout the world. Humans and Pokémon were powerless to stop her as they were slaughtered in the billions. Legendary Pokémon who did not align with her cause would find themselves on the other end of a blade.
Soon, all of humanity was wiped out, and only a few Legendary Pokémon remained.
The Arceus’s job was done, but she wasn’t satisfied. So, she left her original world and ventured into others. She vowed to purge the multiverse of humanity, so that she and her fellow Arceus may live in peace… and so no one may make the mistake that she had made once before. They say that whenever she enters a world that the destruction of the world is all but assured.