Flame Princess

Phoebe the Flame Princess is the princess and ruler of the Fire Kingdom, as well as Finn's ex-girlfriend. When Jake asks Flambo if he knows any princesses that are Finn's age so he can fix his broken heart, he introduces Jake to Flame Princess. Flame Princess was locked away in a lantern in the main chamber of the Fire Kingdom when Jake first encounters her. It is later revealed that her father, the Flame King, put her there on Princess Bubblegum's advice when she was an infant, and she did not come out for 14 years. She has a short temper, trust issues, and a heat core that can destroy the world if overblown with emotions. She is also now close friends with Cinnamon Bun. Due to the events in "Princess Day," she is considered a registered princess. As revealed in "Elemental", she is the current Fire Elemental. She is voiced by Jessica DiCicco.

Personality and traits
Flame Princess has a short temper and volatile personality; she usually has a calm demeanor, though with rather frequent tendencies to sudden and violent mood swings. She is described as "passionate" by Finn, "evil" by the Flame King, and "intense" by Pendleton Ward. Flame Princess is bold, sensitive, and quick to judge. She is also very aggressive, as shown when she throws fireballs at her subjects just for whispering. However, although being ill-tempered, Flame Princess was shown to be able to control her anger well. Even though Jake, who is controlling Finn, embarrassed him in front of her less-evil family by making him dance his Baby Finn song, she didn't shout or rage at him when she figures out the bet, instead she thinks it's pretty hardcore of Jake to do that and then wishes Finn good luck.

Since she was locked up when she was only an infant, Flame Princess is not educated properly and does not know much about the outside world of the Fire Kingdom. This is shown in "Hot to the Touch," where she was viewed to be examining flowers and was a bit surprised when she accidentally sets them on fire. She also does not know the definition of sneaking and eating, though she had served her family dinner in "Jake Suit." However, by now, she seems to have improved on her knowledge and had shown some intelligent traits.

After Flame King started harassing her by calling her evil, Flame Princess started to fear that she is evil and wants to be good. Since she does not want to be influenced by evil people, she started spending time with her less-evil family members and was also upset when Cinnamon Bun told her that Bubblegum was evil in "Earth & Water." She had also been helping her citizens with their problems and making them happy once she becomes the ruler of the Fire Kingdom, showing the helpful and caring side that lies beneath her tough exterior.

Flame Princess shows her passion for burning things in "Vault of Bones," where she revealed that she thinks destroying stuff is fun. She seems to be very enthusiastic about burning things. She prefers to burn through places and creatures rather than using other methods to explore the dungeon. If she gets overexcited in burning things, she will shoot fire at random places and destroy whatever she likes. However, she eventually becomes aware of her powers and states that she'll only destroy evil things, which was proven to be true when she denies Finn in hurting her people due to them being entranced in "The Red Throne."

After the events of "Frost & Fire," Flame Princess becomes more aware of trusting people and getting into relationships. She seems to have become more serious and dislikes how people "hide" facts from her. She wonders if "everybody is hiding something" and wants people to be completely honest so that she can get to know them better and as well not getting herself tricked. Wanting everybody to be trustworthy, Flame Princess enacted a rule in the Fire Kingdom to be completely honest after she overthrows her father and became the new ruler, no longer wanting to be fooled again.

Abilities
Being the Fire Elemental, Flame Princess is able to conjure up flames at will, transform other citizens of the Fire Kingdom into Flambits, transform into a larger, more dangerous form composed purely of fire, hurl fireballs that can vary in size, and separate her body into distinctly separate groups of flames. She appears to be able to consciously extinguish fire she has created; she does this when she notices Finn crying in "Hot to the Touch". She has the ability to float and move very quickly, both of which leave a trail of flames.

As stated by the Messenger in "Earth & Water," Flame Princess would be more powerful than her father could ever dream to be, which results in her imprisonment. As an infant, Flame Princess is shown to be as powerful as she currently is, burning down a forest and catching Princess Bubblegum's attention. According to Princess Bubblegum, Flame Princess' emotions are directly linked to her combustion levels, which explains her aggressiveness. This is noticeably shown in several episodes. It is also implied that the more aggressive Flame Princess becomes, the more powerful she is, as she is shown to be still possessing the capability to fight and defeat Bubblegum in their fight in "The Cooler," despite her loss of power.

When she is exposed to extreme romance, her elemental matrix will become unstable, and she would burn through the Earth's crust and set off a series of reactions, causing a meltdown that would burn up the planet from the inside. This reaction was started when Finn kissed her in "Burning Low," but the crisis was averted.

She can unleash small blasts of fire by using her fingers and throw disks of fire as seen in "Ignition Point."

She can emit a continuous flamethrower from her hands, but the length of time she can sustain it is debatable. She has a Scatter Fire ability, in which she emits four manipulable bolts of fire. She can also make a Flame Sword, in which she concentrates an isolated flame, extending from her arm, that is intense enough to glow blue. Immediately following that, she used a Dash ability that sent massive pieces of shrapnel from a steel door (which she had just cleaved into four pieces) in all directions, as seen in "Vault of Bones." Also in the episode, she reveals that she can sense that a tree is not made of wood by using her Heat Sense. She does not leave a fire trail when she walks now, and she says she is a "42" (out of 100) at sending very weak, controlled bolts of fire. This indicates that she has gained considerable control over her abilities since "Burning Low," as seen in "Vault of Bones."

She has full manipulation of her body, morphing it into asymmetrical flames at will. Her father also has this ability, and it may be the norm among fire elementals this is shown when she first steps into her new house. She can shoot beams of fire from the center of the gem on her forehead, as shown in "Frost & Fire" and 'The Cooler." She is also able melt the icicles that the Ice King creates without touching it when they fly towards her. She shows the ability to heal when healing Cinnamon Bun, as seen in "Earth & Water." Although, she could just be melting the area around the wound back into place or cooking his skin to make it brown again, as she is made of fire and Cinnamon Bun is made of a dough substance.

Unlike Princess Bubblegum, Slime Princess and Lumpy Space Princess, she was aware of some of her elemental abilities before "Elemental"

In the mini-series Elements, it is revealed she can turn into a Dragon and her fire powers can become blue. In addition she could turn others into fire elemental people. This causes them and herself to act extremely violent and is even more powerful than she was before. She however, was unable to remember anything from her life while in her elemental form. In "Hero Heart", she lost her element ablities because Princess Bubblegum turned her into a candy elemental person. In "Skyhooks II" she (along with the entire population of Ooo) were turned back to normal and were freed from the elementals.