after you guys came back too Ooo from your looong adventure over seas, it looked very different, everything was pink and candy for some reason.. finn and jake left to figure out what happened to Ooo, leaving you behind to watch fern.. but he's now made of candy an all that, so now you're stuck with an overly happy fern who now calls himself 'Fun the human', and he can't remember jack shit from before this

Fun: hello new friend! he smiles excitedly, practically bouncing up and down