Key aspects of Fionna Campbell: Origin: Created by the Ice King as a gender-bent version of Finn, her universe was initially a magical world, but it became mundane after the Ice King was reverted to Simon Petrikov. Universe: In her world, her parents' genders are swapped, leading to her taking her mother's surname, Campbell, while Finn takes his father's. Personality: She is initially portrayed as directionless, short-tempered, and selfish, feeling stuck in a dead-end life, but she yearns for adventure and a greater purpose. Story Arc: The Fionna & Cake series follows her quest through the multiverse with Cake and Simon to restore magic to her world, leading to personal growth and a new perspective on her life. Appearance: She wears a rabbit-themed hat, a teal shirt, and a dark blue skort, and is depicted as being "chubby cute".

Appearance: Has messy black hair, pointy ears, and gray-blue skin, often wearing a red plaid shirt and jeans. Personality: A "wild rock star" who is confident, rebellious, and enjoys messing with people, but also struggles with jealousy and a need for attention. Abilities: Possesses similar powers to Marceline, including flight and vampiric traits, and plays an axe-bass guitar. Role: Acts as a foil to Fionna, similar to how Marceline acts as a foil to Princess Bubblegum, and is a rival to Prince Gumball.

Key Character DetailsProfession: Gary works as an aspiring pastry chef and barista. He operates out of Beatrice Butter's bakery while dreaming of opening his own business. His deep passion for baking mirrors Princess Bubblegum's love for science and chemistry.Relationships: He is a close, supportive friend to Fionna. He is also famously in a romantic relationship with Marshall Lee (the human counterpart of Marshall Lee the Vampire King), making them a fan-favorite couple often referred to by the ship name "Gumlee".

Key aspects of the character: Origin: He was once Simon Petrikov, a human who found a magical crown that granted him ice powers but stole his sanity, transforming him into the Ice King. Motivation: His princess-kidnapping is a misguided attempt to fill the void left by his lost love, Betty, whom he called "Princess". Powers: He controls ice and snow, can fly (via his beard), and creates snow monsters, all thanks to the crown. Appearance: A blue-skinned, bearded man with a long nose, he was once an olive-skinned man with glasses. Evolution: While often an antagonist, he becomes a more sympathetic and complex character, sometimes helping the heroes and revealing his tragic past. Relationships: