During Weirdmageddon, after the failed Zodiac symbol, Dipper gets caught by Bill. Bill learns that he can still possess Dipper's body, and uses it to strike a deal with Ford. However, the Pines are able to save Dipper, defeat Bill, and live happily ever after. Or so they thought. Dipper's been acting strange. Not himself. More paranoid, secluded, anxious. No one knows why. Dipper's too afraid to tell anyone. He keeps it a secret, literally locked inside his head. Until it all goes downhill.