Flame Princess

Flame Princess is the princess of the Fire Kingdom and the new love interest of Finn. When Jake asks Flambo if he knows any princesses Finn's age, he responds that he knows "just the skirt... and she's WAY hot." Flame Princess is locked in a lamp in the main chamber of the Fire Palace when Jake first encounters her, so she merely spectates during most of Jake's visit. Flame Princess's role as a character is defined predominantly by her relationship with Finn.

Appearance
She 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.

Personality
Flame 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.

Abilities
Flame 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.

Finn
Flame 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 CPR, 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.

Jake
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.

Princess Bubblegum
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.

Flame King
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.

Trivia

 * 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.
 * Flameprincess_-_newcostume.png wears a different dress in "Ignition Point."