Flame Prince is the gender-swapped version of Flame Princess. He was created by Natasha Allegri in her artwork, and was featured in the episode, The Prince Who Wanted Everything.
He has hair made of flames styled into a mohawk and a big red jewel on his forehead. He also has yellow skin and pointed ears. He wears an orange and red suit and similarly colored boots, which each have a red jewel on them.
In The Prince Who Wanted Everything, Flame Prince was captured by Lumpy Space Prince. How ever Fionna Rescued Him as well a Marshall Lee, Prince Gumball, and Turtle Prince.
In the Fiona and Cake comics Flame Prince Fights Ice Queen to Protect Baby Fire Lions. While they are fighting Ice Queen places a Heated Salt Crystal in his chest turning him cold and knocking him out. When they get to the treehouse he is shrunk to a Fire Booger or Fire Boog as Cake calls him. He speaks Cat and cake says he needs to find his lion pride and save them From Ice Queen. Fionna feeds Flame Prince a match and then leaves to change out of her wet clothes. Suddenly Marshall Lee comes crashing through the ceiling. He is hurt and asks for Fionna. Fionna Comes in and Marshall Lee tells them Prince Gumball is in trouble. On their way to the Candy Kingdom Flame Prince is in Fionna's backpack. After Fionna Rescues Prince Gumball, he is about to make her something in his Anceint Magical Oven but he realizes the pilot light is out. Flame Prince Willingly Volunteers and Gumball makes her a sword with 3 Wish Candy Stars. Prince Gumball questions where Fionna got a Fire Elemental and she tells him. Gumball tells Fionna about how a Heated Salt Crystal Drains all of the victims body heat until they die. Fionna gives him Flame Prince so Prince can temporarily raise his body heat. Prince Gumball Heats him up enough that he returns to his boy form. Cake makes him a suit and Teaches him English. When Fionna sees the restored Flame Prince she compliments him. He tries to touch her but accidentally sets her hat on fire. When Cake puts the fire out it hurts him. Gumball explains that the change is temporary and he will become a fire booger again at midnight. Flame Prince has to go on a fancy dinner date with Ice Queen in exchange for his Lion Pride back. Fionna and Cake go along disguised as one big Fire Lion. They go in past the door Gertrude is gaurding and sit down with Ice Queen Ice Queen tries to attack Flame Prince. Fionna Rips off her disguise. She starts to fight Ice Queen and her hat falls off. Ice Queen is beating Fionna. Flame Prince Tries to help by throwing Fireballs. However, the fire balls land around Fionna and set her hair on fire. Fionna gets hurt by the fire and Flame Prince realizes Fire Hurts People. Fionna Cuts her hair off to shoulder length so she won't hurt Flame Prince by putting out the fire. Ice Queen Traps Fionna and Flame Prince. She Takes the Heated Salt Crystal out of Flame Prince and Puts it in her. Ice Queen Melts and all of Ice Kingdom with her. Lumpy Space Prince and Gummball show up. Flame Prince and the Fire Lions go inside of Lumpy Space Prince. When they get to the Candy Kingdom, Cake and Prince Gumball make Flame Prince a tiny kimgdom. Before Flame Prince leaves he tells Fionna "You Look Pretty" and Kisses her.
The Fire Lions are like Family to Flame Prince and he raised them. He will protect them at any cost.
Cake was Flame Prince's First friend not made out of fire. When He was shrank Dow to a Fire Booger Cake treated it like a pet. However, Cake teaches him some English and convinces Prince Gumball to help make him a kingdom.