The inhabitants of the city are written off from the relatives and friends of Alex. Perhaps that is why the characters turned out to be so sincere, and their behavior recognizable.
Dipper Pines
Dipper is similar to his creator, Hirsch wanted the hero to be as nervous and insecure as Alex himself at his age.
The author hoped that such a character would have a special connection with the viewer, but soon realized that it was not so interesting to watch an ordinary weakling.
Dipper was allowed to take risks and dream big, so the character shows real courage at the right time.
Mabel Pines
To create the image of Mabel, Alex constantly thought about how his sister would have acted in this or that situation, and based on her behavior in elementary school.
Alex took everything into account to the smallest detail: as a child, Ariel also adored colorful sweaters, fell in love with someone every week and dreamed of a tame pig.
Sous Ramirez
Sous, the good-natured and clumsy employee of the Mystery Shack, was based on an acquaintance of Alex from college.
He always sat in the computer lab and offered to help, although he was more likely to break something than fix it. Hirsch considered him a fairly sincere person and wanted to add the same character to his series.
Bill Cipher
One day, Alex asked his mother why there was a pyramid on the one dollar bill. She jokingly replied that it was an ancient symbol, and the founders of the United States were in secret societies. The boy immediately imagined them worshiping the triangular monster.
Later, Alex added arms and a top hat to the pyramid - this is how Bill, the main villain of Gravity Falls, appeared.
But Hirsch borrowed the voice and manner of speech for the character from his second grandfather.
Both grandfathers served as the basis for the image of Uncle Stan. Most of all, the hero resembles Alex's relative on his father's side: the animator describes him as a big, rude guy who wore a chain and saved every cent.
Alex and Ariel's real-life uncle was inspired by Stan's great-uncle, owner of the Mystery Shack.
Stan Pines