Jake enters the Fire Kingdom to court Flame Princess on behalf of Finn, who is feeling heartbroken after having been pushed away by his previous love interest Princess Bubblegum. Jake sings her a song and accidentally kills her father's jester by spilling water on him, both of which she apparently enjoyed; Though, she does not react much when Prince Finn kills Jake. In "Burning Low." Jake does not interact much with Flame Princess but they seem to be friends and Jake has approved of her and even helps Finn in courting her with a poem. In "Ignition Point," they interact much more and they seem to be comfortable with each other, it was Jake who suggested going to the Fire Kingdom to get her the scented candles.
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 regains consciousness and angrily asks Finn why he doesn't like her; Finn replies that he does like her, which causes her to blush in surprise. Confused by Finn's apparent fickleness, she slaps him and warns him never to mess with her again—unaware that Jake was the original "Prince Finn." 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 her from a bush at first, calling her innocent 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 causes her pain, causing Flame Princess to believe that Finn is intentionally hurting her. She leaves in a huff without allowing Finn a chance to explain, not listening to his claims that he was not trying to hurt her.
After a brief chase, she concludes Finn is trying to impede her, so she decides to turn the Grass Lands into her own fire kingdom. She begins by heading for Goblin Kingdom to set it and its citizens on fire. Finn and Jake attempt to stop her with robo suits made by Neptr, but Finn only attempts to talk her out of it rather than put out her fires. When Finn realizes he cannot make her understand his feelings, he tears a hole in his robo suit and cries wishing he could "just like a girl." One of his tears falls onto the flames as she is walking away from him, causing her to turn and witness him crying. She becomes convinced that he is a water elemental, saying that all he does is cry and 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, and then leaves saying, "Bye, Finn."
In "Burning Low," she and Finn are dating. Finn helps her build a new house in the Grass Lands out of wood scraps, and she tells him that she loves it. Her flames trail over to Finn's foot and he is surprised to realize that it doesn't hurt as bad as it used to; though, once the flames crawl up his leg he screams in pain and jumps into the water. Once he's out of the water, Finn and Flame Princess hug; although, Finn has to wear many layers of tinfoil to protect himself. While walking home, Finn asks Jake for advice about dating, to which Jake explains the concept of "tiers" and tells Finn that he should move on to Tier 2, which is kissing. Later in the episode, Finn goes on a date with Flame Princess (off-screen) and tells Jake that, he wasn't able to kiss her yet, so he is still on Tier 1. Jake advises Finn to write a poem for Flame Princess in order to move things along. Finn tries to think about Flame Princess' qualities to which he says, "She's bright. She's beautiful. She makes me feel confused, like something's filling up my chest—like I can't breathe. Is it because she's so dangerous?" Finn ends up going outside and watching the sunrise, which gives him inspiration to write. He takes the finished poem over to Flame Princess' new house and reads it to her. After he's done they stare into each other's eyes and kiss. The kiss triggers a reaction and causes her to burn so hot that she melts through the ground. As she's falling, Finn grabs Jake's arm, ties it around himself and jumps down after her. Flame Princess' reaction is halted by lack of oxygen, and when Finn catches up to her she is extinguished and passed out. Though nearly out of oxygen himself, Finn picks her up and tells that he needs her to be okay. He then breathes into her mouth, which causes her to re-ignite. Jake pulls them out of the hole and both of them are all right. Finn picks up a rock and kisses it, then hands it to Flame Princess who kisses it as well.
In "King Worm" Flame Princess is feeding Finn (whom she calls "honey") soup; first lovingly, then angrily when he hesitates (he was confused, having been with Princess Bubblegum as her king and husband seconds earlier). However, Finn soon discovers that he is in a dream and she is not the real Flame Princess.
In "Ignition Point," Finn and Jake travel to the Fire Kingdom to retrieve Flame Princess' scented candles. 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 has "options in case Flame Princess doesn't work out."