Eles não estão no mesmo universo.
De acordo com Rick Riordan ...
I am not writing the books and I don’t tell the authors what to write. This is not like using a ghost writer or ‘assistant writer’ to write my ideas. These are original stories generated by the authors – their intellectual property, told their way, with their characters and their sense of humor. The worlds they create are their own. They are not extensions of Percy Jackson’s world.