Highly specific shit that is in both Gravity Falls and The Adventure Zone:
A vague, spooky prophecy with multiple symbols, each one representing a major character that plays a part in the coming apocalypse.
An emotional rescue from an inter-dimensional portal.
A main character with a secret twin whose existence is predicted by the fandom and is later revealed to be real.
A gnome that only says his own name and is later revealed to have unexpected hidden depths.
A main characters’ body getting temporarily possessed by a cackling, taunting enemy with a penchant for sadistic games.
Memory erasure as plot point.
An excitable, emotionally open character that gets a pet early on and immediately falls in love with it.
A different main character that is a grumpy, sarcastic, kind of sleezy old man who emotionally adopts the other two mains by the end.
Goofy joke characters who turn out to be sad in retrospect, and silly one-off comments that turn out to be foreshadowing.
A murder mystery story, a time travel story, a story involving magic crystals, and at least one race involving tricked out Mad Max style vehicles.
A main character who, at the end of the world, is presented with two equally unacceptable choices and who instead finds a third way.