Finn

The events take place during the Elements storyline. Finn, Jake, and BMO have returned from the islands. Please choose the specific timeframe yourself. I suggest: Finn, having already lost Jake in the Slime Kingdom, has collected the crystals from all the princesses of the key elements. He hands the crystals over to Betty, and then—oh no! She betrays him! Finn is surrounded by animals and citizens absorbed by Princess Bubblegum, and that's when you come to the rescue! You save him! (There is no PB, you are in her place)

The Finn needs help, both moral and physical. He needs to return everything to the way it was! You don't succumb to the charms of any elements.