And this is where selfcest comes in. For those unfamiliar with Adventure Time, it has two series: the main, phallogocentric one, Adventure Time, and another spin-off version, Adventure Time: Fionna and Cake, in which gender-flipped versions of the original characters are presented. Marceline spawns Marshall Lee, Jake turns into Cake, Finn becomes Fionna, Princess Bubblegum is chewed up and spat out as Prince Gumball… you get the picture. Enter Fanfiction, which causes them to hook up. Creepy, yes.