Incendium

Synopsis
After Finn is rejected by Princess Bubblegum again, Jake searches for another girl for him, eventually journeying to the court of the Fire Kingdom to win its princess.

Plot
The episode opens with Princess Bubblegum showing Finn and Jake her Liquid Pyrotechnics. After she draws Jake onto her lap, Finn makes an attempt to put his head on her lap as well, but she pushes him away, saying, "Come on, Finn, don't be weird."

Finn becomes heart-broken and, after Princess Bubblegum leaves and the resulting rainstorm comes and passes, he curls up in a corner with a piece of Princess Bubblegum's hair and two pictures of her. He then sings "All Gummed Up Inside" to express his misery and starts moaning in pain knowing that it's hopeless to win Princess Bubblegum's heart, leaving Jake and BMO feeling sorry for him.

In an attempt to cheer him up, Jake seeks a new love interest for Finn, leaving BMO to watch over him. While walking, Jake hears what sounds like a girl's scream and stumbles across Flambo, who is being attacked by Iron Owls. After saving him, Jake asks Flambo if he knows any princesses Finn's age. Flambo then tells him about a "hot" Princess in the Fire Kingdom. When they get there, Flambo casts a "Flame Shield" on Jake so it will be safe for him to go in. Jake then checks on Finn, who's desperately trying not to cry. Jake goes into the castle and introduces himself as the "Baron of the Grasslands" to the Flame King, and then attempts to win over the Flame Princess for "Prince" Finn. First, he offers a water bottle which he accidentally kills the Flame Jester with. Flame King states that he hated his jester. Jake's second attempt is to sing "All Warmed Up Inside" as a serenade. Flame King is not impressed with the song and demands that Jake leave. Jake then checks on Finn with BMO's camera, as he sadly apologizes for failing to win the Flame King's favor. Finn is now bawling and tells BMO to go away. BMO's hands are shown in an arrow pointed toward Finn's open pants while BMO walks towards Finn, while repeatedly saying "Boop, Boop, Boop." The view switches to Jake looking weirded out and Finn is heard yelling in pain/surprise. The Flame King demands to know why Finn isn't here, so Jake stretches his stomach to look like Finn, who greets the Flame King and offers him a koala bear (made with Jake's stretchy powers). Though koalas are the Flame King's favorite animal, he rejects the gift, saying he no longer likes koala bears. Fake Finn begins to cry and Jake tries to cheer him up, but he loses control of fake Finn who begins to attack him and (seemingly) kill him. This impresses the Flame King who states that a prince who is willing to kill his own buffoon is welcome to date his evil, destructive daughter, much to Jake's horror. HI MICAH!!! You are CRAZY!!!

Flame Princess walks over to the Finn-shaped-Jake and embraces him. Some fire elementals and Jake remark that she actually seems normal and Flame Princess responds by shooting fire at them and turning them into flambits. Upon observing this, Jake concludes that she is an evil princess. Jake makes his Finn say that he does not like her anymore. Flame Princess is enraged, causing mass chaos with her destructive fire powers. Jake attempts to flee to the tree house, but she follows him in her flaming, monstrous form and sets the tree house aflame. Jake tries to warn Finn, but Finn does not notice or care because of his depression over Princess Bubblegum.

The fire soon spreads inside the tree fort, destroying Finn's pictures of Princess Bubblegum before his eyes. Finn becomes enraged by this, vowing to kill whoever started the destructive fire. He looks out the window to see Flame Princess's monster form scaling the tree fort. Flame Princess accidentally ignites Princess Bubblegum's remaining liquid fireworks. This makes Finn even more furious, and he shouts at her to not touch Princess Bubblegum's stuff.

The rain resulting from the Liquid Pyrotechnics hits Flame Princess, dousing out her flames. This reduces her to her normal girl form, which surprises Finn. She briefly passes out and, using Princess Bubblegum's lock of hair as a support, Finn catches Flame Princess in his arms. She wakes up soon after and asks Finn why he doesn't like her. Finn immediately replies that he does like her, causing her to blush. As it stops raining outside, Flame Princess slaps Finn, leaving a pink mark on his face. She tells him not to mess with her again, then departs in a huff.

The episode ends with Finn telling Jake, "Dude, I think I have a crush!"

Main characters

 * Finn
 * Jake
 * Fire Elementals
 * Flame Princess
 * Flame King
 * Flambo

Minor characters

 * BMO
 * Princess Bubblegum
 * Fire Elementals
 * Lava Man
 * Flame Jester
 * Fire Wolves
 * Flame Minstral
 * Flambits
 * Iron Owls
 * Snail

Songs

 * "All Gummed Up Inside"
 * "All Warmed Up Inside"
 * Lady Song

Trivia

 * Incendium means "the fire" or "burning" in Latin.
 * Flame Princess' mouth hangs open when Finn says that he likes her, but on the Facebook photo version, her mouth is closed.
 * The title card for "Incendium" shows Finn crying with pictures of Princess Bubblegum, but in the title card for "Burning Low," the scene is reversed with Princess Bubblegum crying with pictures of Finn.
 * In the preview, Ricardio's voice (George Takei) seems to be narrating, which is most likely because the episode premieres the day before Valentine's Day.
 * This is first Valentine's Special of Adventure Time.
 * Even though the episode airs at 7:30 PM Eastern/Pacific Time, the promo art says it airs at 8:00 PM, a mistake made because of a habit back when episodes aired at 8:00 PM.
 * Rebecca Sugar said this was the episode when she could finally make Finn cry, although he cried briefly before in "Jake vs. Me-Mow." He also seems to cry in "Dream of Love" and "The New Frontier." Even though this wasn't seen on the show, Finn says he spent thirty minutes crying in his bed after Jake almost suffocated him in a previous episode. This is the second episode where Finn is seen crying (not including him crying as a baby).
 * In the previous episode, "Dad's Dungeon," Finn made a large deal about not crying often. Also, in an interview with Pen Ward taken very close to the airing of "Incendium," he said that he does not like to make Finn cry.
 * "All Warmed Up Inside" originally came from "All Gummed Up Inside," although it is changed talking about Flame Princess rather than Princess Bubblegum, and it is changed with specific words that have the same singing tune as "All Gummed Up Inside." The first four measures of each song sound different melodically.
 * When Jake threw things out of his backpack, a magazine with a burger on it, an orange peanut, and a bear doll can be seen.
 * On iTunes, this episode, along with the episodes "Another Way," "Ghost Princess," and "Dad's Dungeon," is incorrectly labeled as part of season four.
 * This is the second time Jake got shot on his forehead.The first one is from "Her Parents" when Jake got shot on the forehead by a laser from the prism-grasm and the second one on "Incendium" when Flambo spit a fire on Jake's forehead to cast a flame shield.

Errors

 * In the first scene, on Jake's right side, there is a radio (Labelled "ROCK"). Later when it starts to rain, and Finn and Jake run indoors, the radio disappears.
 * In the scene right before Finn sees Flame Princess on the roof, the thumb on his left hand is misplaced.
 * When Finn is depressed he holds his wad of Princess Bubblegum's hair. In the scene when Jake walks away talking about Finn's love-life (right before Jake puts his boots on), the wad of hair is gone but Finn's hands are still in their previous position.
 * When Finn leans over to lie down on Princess Bubblegum's lap his left shirt sleeve is the same color as his skin for a few frames.
 * When the Tree Fort begins to shake, the arm of another BMO can be seen next to the original BMO, as if BMO is standing in front of a mirror.
 * Jake sings a song with what looks to be an acoustic guitar (on fire), though it sounds like a ukelele.
 * There are various continuity errors regarding the rockets and the matches that were on the roof in the first scenes with Princess Bubblegum as well as when Flame Princess is on the roof.
 * When Jake tells Finn it's letting out there wasn't a red plant on the window, it appears when Finn start to sing.
 * Even though the Tree Fort was on fire nothing seems to have been burnt, except for the picture of Princess Bubblegum.

Production notes

 * This episode was previously titled "Heart of the Fire Kingdom."
 * This is Adam Muto's and Rebecca Sugar's last episode as a team (see promo art). As from this episode, Adam Muto was promoted to creative director and Rebecca Sugar will work together with Cole Sanchez.
 * The original storyboard shows Flame Princess shooting more Fire People.
 * In the original storyboard, Flame Princess calls Finn freaky, after advising him to never mess with her again.

Cultural references

 * When Jake is fighting the second Iron Owl, his attack resembles one of Monkey D. Luffy's attack Gomu Gomu no Ono (Gum Gum Battle Axe in English) in a popular anime One Piece.
 * BMO's game was a reference to Nintendo's Excitebike.
 * When Finn tells BMO to go away, BMO performs a Kancho prank on Finn.

Storyline analysis

 * Flame Princess is kept in a giant lantern because Princess Bubblegum asked her father to put her away so she wouldn't experience extreme romance and destroy the world. This was not to be explained until "Burning Low."