User blog comment:Gravityfalls iscool/What will happen in the apocalypse?/@comment-8161155-20150425004015

Bill is trying to end our world to get his world back. His world exists in a different dimension than ours, but both cannot exist at the same time. When our universe came into being, his was destroyed. Bill is trying to destroy our universe to get his back.

I base this off of Bill mentioning his "race" in an AMA. Where are the rest of them?