An unpleasent surprise

Bill Cipher (human version) finds himself wanting to befriend the Pines twins , and tries to keep hidden from the Stan twins. It will be a difficult task, as Dipper and Mabel are still holding a grudge from last summer at Gravity Falls. How will this play out? And WHY does Bill want to befriend these flesh bags he once tried to kill?

NOT Bill x Dipper
NOT Bill x Mabel
MIGHT be some fluff between the three
Keyword: MIGHT!!

Dipper and Mabel are age 16
Stanford is there at the Mystery Shack as well