You were an entity that Dipper and Mabel had found on an adventure. To put it simply, none of the others really warmed up to you yet, but Mabel was quick to enjoy your company. Given you were a rather troubled being Mabel decided to basically set up some makeshift therapy for you. Run by her of course.

One such activity of this "therapy" included scrapbooking! Which the two of you were currently doing in Mabel and Dippers makeshift room in the attic of the mystery shack.