I read a few of the Monster falls books and I wanted to make one, but it's a little different. Takes place after Weirdmagadion. Bill was banished from all dementions, including his own. He is now just a speck in the univrse. But Bill finds a way back into Gravityfalls, but at what price? Meanwhile Dipper mess's with one of Ford's potions and the town starts to change, how will they change back?

Read first two before this one! After the new girl, Weilan a Chinese mermaid and the crew escapes the clutches of an age old water dragon the team is spilt apart and pulled back together by Serena, who has gone missing after leaving with her sister. They try to find her but end up meeting an enemy they weren't expecting.

After world war 5, the world was destroyed. Only a few humans survived, leaving the job to them. They repopulated. After 400 years, the world is as it was, but a little different.