Spoilers for Gravity Falls.
Gravity Falls is a fantastic, magical place. Creatures like gnomes and unicorns are real, but there is also a darker, more sinister side to the magic of the city. The second season of Gravity Falls explores the darkness of magic and human relationships. Still, all shows and summers must end eventually.
Gravity Falls embodies summer and imagination. The lack of structure leaves plenty of time for play and exploration, both of which Mabel and Dipper enjoy plenty. Both of the children are at an odd age. When the show starts, they are 12. To themselves, they are clearly children. However, during the summer, they turn 13. This age is more grown up. They are finally teenagers. This is also around the time when the show starts to take a turn. They begin to see their Grunckle’s villainous actions and relationships and secrets that were not apparent before. Dipper sees darkness (in the form of Bill Cipher) amplify fears and destruction and take over the bodies of his friends, family, and even his own body. Their beloved Grunckle eventually defeats Bill, but it is largely implied that the defeat is not permanent.
As twins, Mabel and Dipper both face the same hardships of growing up, but Mabel generally handles them better than Dipper. In being unconcerned with being cool and her natural extroversion, Mabel turns into a cool and likeable teenager. She is unashamed of her childish obsession with unicorns and all things sparkly. This doesn’t win her points with her “cool” peers, but it does win her points with nearly everyone else. Conversely, where Mabel is outgoing and happy, Dipper is reclusive and anxious. As he gets older, his anxieties lead to rage and seclusion.
Dipper and Mabel end up relating to the uncle least like them at their age. Though Stanford feels that he relates more to Dipper’s bookish tendencies, he was actually the better liked of the two growing up, similar to Mabel. He also brought his childhood hobbies into adulthood in unabashed pursuit of weird fantasy and aesthetic fulfillment. Likewise, Stanley was anxious, angry, and didn’t fit in with others, similar to Dipper. Though their hobbies may be more appealing to one child over another, their personalities match the child to whom they are the least close.
The real magic of Gravity Falls is that it is a place for Dipper and Mabel to explore adulthood without long-lasting consequences. They can make social errors and explore new feelings away from their school peers. Even when everything is at its worse, Mabel simply has to pull out her scrapbook and remind everyone of all the good times of the summer and growing up. At the end of the summer, even after their biggest adventure, everything resets. Everyone and everything is weird in Gravity Falls, so Mabel and Dipper can explore how they are weird and how the world is weird in a safe environment. Then, at the end of the summer, when they’ve defeated their demons (literal and figurative), they can go home having learned about themselves and how the world works.