AppearanceShe has long vermilion (orange-red) hair made of fire that, when down, falls down her back, and when up, takes an appearance similar to flames. Her skin is a sunglow color (yellow-orange) and she wears a long tank top dress that touches the ground. She appears to have a huge ruby on her head and one on her dress that may show her royalty instead of a crown. Her color scheme changes when wet, her skin changing to a pinkish hue and her hair to a lighter brown-pink. She has a body-type similar to Fionna's.
PersonalityFlame Princess has a volatile personality. She is described as "passionate" by Finn, "evil" by the Flame King, and "intense" by Pendleton Ward. The Flame King also remarks that she is difficult to control. She seems to be very sensitive and quick to judge. She is also prone to unprovoked fits of aggression, as shown when she throws fireballs at her citizens just for whispering. Based on this outburst and her imprisonment in the gas lamp it is likely Flame Princess has a destructive nature, though it is possible her nature is a result of her imprisonment. Flame Princess is also impressionable in a positive way. She is very happy when Finn calls her beautiful. She was also interested when Jake was giving her gifts in the episode "Incendium" and excited when her dad let her date "Prince Finn." This excitement quickly turns to anger when "Prince Finn" rejects her.
In the episode "Hot to the Touch", Flame Princess shows curiosity about her new surroundings by examining flowers. This sets them on fire and she seems a bit surprised by the reaction, indicating she doesn't know much about lands other than the Fire Kingdom. At the end of the same episode she shows that she likes Finn, but thinks that they can't be together because they are opposite elementals (she thought Finn was a water elemental because of his crying).
In "Burning Low," she seems to be calmer and she seems to be able to handle pain, illustrated when Finn jumps into the pool while his foot is on fire, and she doesn't react.
AbilitiesFlame Princess is able to conjure up flames at will, transform other citizens of the Fire Kingdom into flambits, transform into a much larger, more dangerous form composed purely of fire, hurl fireballs that vary in size from about baseball-sized to larger than Finn, and separate her body into distinctly separate groups of flames, shown when she ambushes Finn in "Hot to the Touch." She appears to be able to consciously extinguish fire she has created; she does this when she notices Finn crying. She can also "fly" and move very quickly, both of which leave a trail of flames.
She is weak against water, shown after unintentionally setting off some of Princess Bubblegum's liquid pyrotechnics and when she puts her hand into a pond. The liquid pyrotechnics caused her to become unconscious, and touching the water in the pool caused her apparent pain. The fires that Flame Princess make are a part of her, and snuffing or dousing the fire causes her pain.
She can travel quick at a large distance by transforming into fire and move to destination then return to original form.
She has an extremely unstable makeup. If her elemental matrix is exposed to extreme romance, she would sink through the earth's crust and set off a series of reactions that would cause an meltdown that would annihilate the planet.
She can use her fingers to unleash small blasts of fire and throw disks of fire as seen in "Ignition Point." Although she seems to have been stabilized as she doesn't leave a trail of fire as she walks anymore as seen in "Vault of Bones."
She can use her Heat Sense to sense nonliving objects, as shown in "Vault of Bones."
FinnFlame Princess does not actually meet Finn in person until the very end of "Incendium." After she is doused with Liquid Pyrotechnics, she unconsciously falls off the roof of the Tree Fort. Finn catches her as she is falling and brings her inside. She quickly regains consciousness and angrily asks Finn why he doesn't like her, to which Finn replies that he does like her causing her to blush in surprise. Confused about how Finn could say one thing and then immediately contradict himself, she slaps him and warns him never to mess with her again - she was unaware that it was Jake as "Prince Finn" that said he didn't like her just before they arrived at the Tree Fort.
In "Hot to the Touch," Finn wanders into the woods to search for the Princess, after asking Jake about her and saying he "really likes her." When Finn finds Flame Princess he watches from a bush at first saying she is like "the steam off a puppy's nose searching for ham in the snow" and "a cute little flower." She touches a pool of water hurting herself, and Finn jumps from the bush to her aid. He then tells her that he was worried about her and thinks that she's beautiful. This causes her to glow literally and figuratively, causing some fire to spread around Finn and herself. Finn puts out the fires in a panic which hurts her, causing Flame Princess to believe that Finn is intentionally hurting her. She leaves in a huff without allowing Finn a chance to explain, not recognizing his claims that he was not trying to hurt her were genuine. After a brief chase, she concludes Finn is trying to impede her, causing her to decide to turn "this land" (starting with the Goblin Kingdom) into her own fire kingdom. She continues to set the kingdom and its citizens on fire apparently ignoring Finn's pleas for her to stop. When Finn realizes he cannot make her understand his feelings, he breaks down his fireproof suit and cries wishing he could "just like a girl." One of his tears falls onto the flames as she is leaving the ravaged kingdom, causing her to turn and witness him crying. She becomes convinced that he is a water elemental, saying all he does is cry all the time. She comes to the conclusion that they are opposite elementals and that even if they like each other, they would hurt each other. However, Finn suggests that they try to make it work and that he can take it. She seems happy that he would want to "defy nature" for her, and both lean in to hug one another. As they hug, Finn gets burned and pushes her away. She looks at him appearing unsure, but still glowing, and then leaves saying "bye, Finn."In "Burning Low," she and Finn start to date, sharing multiple hugs and eventually kissing. This results in Flame Princess' instablility to activate, causing her to burn through the earth and also causing Finn to dive in after her. When he reaches the bottom and finds her unconcious, he holds her in his arms and gives her artificial respiration, causing her to wake up and rekindle. After being returned to the surface, they share a kiss with Finn kissing a rock and giving it to her; with her kissing the rock in return. The episode ends with the two walking off together.
In "Ignition Point," Finn and Jake travel to the Fire Kingdom to retrieve Flame Princess' scented candles. While there, Finn finds out that Flame Princess is evil, but he seems pleased to know that she could possibly be turned to good.
In "Reign of Gunters," Finn takes the advice of a dating book called Mind Games and tries to act more mysterious, claiming he needs to keep all the ladies in a state of confusion; that way, he always has "options in case Flame Princess doesn't work out."
In "All the Little People", the mini version of her fights against Princess Bubblegum for the love of Finn.
In "Vault of Bones," she went to the Vault of Bones with Finn to prove to herself that she's good. After a giant Goo Skull captures Finn, she rescues him and calls him her boyfriend for the first time. At first, Finn thought he was going to be burned alive because of how Flame Princess approached the Goo Skull, but after he's rescued, Flame Princess says she would never hurt her boyfriend.
In "Puhoy", Finn feels that Flame Princess doesn't like him anymore. He said that he told her a joke, but she didn't respond. In the end of episode, Flame Princess called Finn up and tell him that she didn't get his joke before and she now understands it.
In "Jake Suit", she invited Finn at her house to meet her less-evil family members. She totally didn't even mind that he made a fool of himself once she found out it was because of a bet with Jake. She believes that Finn will win and cheers him on, giving him the support he needs to survive the final stretch of Jake's gauntlet.
In "Frost & Fire", Finn tries to get her and Ice King to fight by lying in order to complete his dream. This, however, leads to Finn attempting to apologize and to continue their relationship, but to no avail as Flame Princess leaves Finn saying "I need some time alone." However it doesn't mean they broke up... as we are quite sure Finn can fix it.
In "Too Old," at the end Jake is talking with Finn. Finn says he has to "Patch things up with Flame Princess." So it is unknown if they got back together or not.
In "Earth & Water," Flame Princess overthrew Flame King and became the new ruler. When Finn tried to apologize to her she accepted his apology. He asked her if they were still going out, she said no but they could still be friends and that he can come by anytime as long as he is completely honest with her.
Jake enters the Fire Kingdom to court the Flame Princess on Finn's behalf, who was feeling heartbroken after being rejected by Princess Bubblegum. Although it is unknown how she feels about Jake directly, she does seem to enjoy his song, as well as the fact that he (accidentally) slays her father's jester. It should also, however, be noted that she also cheered after Jake was seemingly choked to death by (a fake) Finn, and she attempts to catch and kill him after (fake) Finn rejects her. Jake was the reason why she was mad at Finn.
The extent of the relationship between the two is unknown. According to Princess Bubblegum in Burning Low, however, It was she who gave the orders to lock Flame Princess up in the lamp in order to prevent the destruction of earth should anything cause her to become unstable.
In "Earth & Water," when Flame Princess submitted herself to experiments by Princess Bubblegum to control her emotions, Princess Bubblegum had to leave to help Finn and Jake so she had no choice but to put Cinnamon Bun in charge of the experiment. However, he brought Flame Princess to his house to talk. Liking his honesty and after recalling that it was Bubblegum who had her father put her in the cage where she spent her childhood, they both went to the Fire Kingdom and overthrew the Flame King and enacted a policy where lies weren't allowed.
Although her father, the Flame King understands his own daughter as "evil", having said so even in introducing her to "Finn" (Jake molding part of his body into a Finn-shape) when they first meet. Flame Princess hated that her father locked her away in the lantern for all these years and thus refuses to go back to Fire Kingdom after she finally leaves it behind when meeting Finn. However, Flame King's concept of his daughter being evil is merely a factor of all Fire Kingdom citizens being evil and traitorous to one another, with him believing her like others yet with physical instability that would cause harm to anyone around her. He slightly could believe his daughter could gain a "good" alignment if she hung around people like Finn, but he doesn't know if it could work due to Flame Princess' fiery nature.
In "Earth & Water", when Flame Princess was born, Flame King feared she would become so powerful that she would overthrow him. So he had one of his servants to take her to the woods for her to perish. However, the servant took pity on her and gave her to a woodsman, but she wandered around and proceeded to burn the woodsman house and the surrounding forest. She was found by Princess Bubblegum, who brought her back to her father, where the Princess demanded he control his daughter. So, he locked her in a oil lamp-like cage. When Flame Princess discovered this, she and Cinnamon Bun went to the Fire Kingdom, overthrew her father, and locked him in the same cage she was once in.
Extended familyFlame Princess has two unnamed younger brothers and one unnamed older brother serving in the military. Like their sister, they less evil.
Flame Princess has two cousins, Furnius and Torcho, who hate her father because he killed their father in order to take over the Fire Kingdom.
She also has an aunt and uncle who are very judgmental.
- Like Marceline, LSP, and BMO, She did not appear in the Animated Short with all of the other main characters, although she is still considered one.
- Natasha Allegri has drawn Flame Prince, a gender-swapped version of Flame Princess.
- The reason Flame Princess was in the prison was because her 'elemental matrix' was unstable and exposure to romance would caused danger. It was Princess Bubblegum who confirmed this and informed Flame King.
- Flame Princess may like Finn back; she says "even if we like each other we're going to hurt each other," implying she likes him too. She also seems to be happy when Finn admitted that he likes her and smiled when they tried to hug. This is confirmed by "Burning Low."
- Flame Princess refers to herself as a fire elemental and refers to Finn as a "water elemental" (which is technically perfect, since humans are mostly water).
- Flame Princess is the only known princess to have invaded another kingdom (solo).
- Flame Princess's gems may be indicative of her royal status in the Fire Kingdom, similar to the stars of Lumpy Space royalty.
- In the episode "Burning Low", Finn kissed Flame Princess for the first, second, and third time.
- As of Burning Low, Flame Princess and Finn are currently dating.
- She wears a different dress in "Ignition Point."
- Pendleton Ward revealed that Flame Princess will return a little more redeemed in Season 5.
- Flame Princess seems to have broken up with Finn in "Frost & Fire", though it is not yet known if the break-up was official or just temporary.