User blog comment:RunicVamp/Source of Magic?/@comment-3045936-20151029223007/@comment-9249716-20151030052103

or maybe their entities like the horsemen but their powers thrive off of different concepts. It's something I don't think the writers will ever fully explain. About the only other thing I could ever possibly suggest is the idea that they were originally humans who grew in magical power until that power took them beyond human limits.