Pinned Down (BillDip/Bipper AU)

Dipper Pines, a sixteen year old teenager with an energetic and optimistic twin sister, Mabel Pines. After their Summer Vacation at Gravity Falls, another highschool semester came in their way.

Unfortunately, their first day didn't go the way they expected and just as they thought the day wouldn't get any worse, an unexpected classy transferee introduced himself to the class. This student wasn't just any other students though, this one had something to do with the twins' past-especially Dipper's, and it wasn't a very good past.

Dipper, who apparently has no memory of this man unlike Mabel, slowly regains these memories with the help of this man, who actually caused this horrible past.
Will Dipper and this fashionable fellow ever go back to how they were before or will they develop feelings for each other? Or possibly....

A dark and sexual relationship?