Mortal Recoil

Synopsis
Though the Lich appears stopped, an idiotic accident by the Ice King has lead to Princess Bubblegum becoming altered, leading to an unlikely final showdown with one of the greatest evils in order to save all life in Ooo.

Plot
In the previous episode, Princess Bubblegum was dropped stupidly by the Ice King into the Lich's Well of Power, which had melted her body. The episode begins with Dr. Ice Cream and Nurse Poundcake, along with other candy hospital staff, rolling her into the ER trying to stabilize her. They put two scoops on her just before she was flat-lined. Luckily, she was brought back to life. Ice King tries to explain something strange he saw when Princess Bubblegum fell in the well, but Finn is still extremely mad at the Ice King for almost killing her and nearly kills him by throwing his Root Sword at him, telling him "just shut your face, old man". This hurts him emotionally, so he flies away. As a gift for destroying the Lich, the other princesses give Finn a new backpack,since his old one got ripped. Princess Bubblegum is still very ill and is confined to her room, with Finn and Jake acting as her caregivers. When she wakes up she is given a gift of every flower in the Candy Kingdom picked for her.

However, she exhibits strange behavioral problems including spasms, heavy breathing, convulsions and crawling into the bathroom. Finn returns her to her bed and takes some time to confide his feelings to her, asking Jake to leave the room. Finn thanks her for the sweater she made him due to it have "the power of liking someone a lot" because she cared about him and tells her that they should discuss their feelings later, but she is unresponsive. Princess Bubblegum asks Finn in a whisper to bring some objects for her. When Jake and Peppermint Butler return with a cup of tea, Peppermint Butler freaks out, then hisses like a cat and runs away.

While Finn's away, Jake tries to play some music for Princess Bubblegum, but Princess Bubblegum acts psychotic and summons magical fire into the room and scares Jake out. When Finn returns to the hall outside, he is holding an assortment of items, which he reveals are things like gasoline, bleach, ammonia, lighter fluid, plutonium and other hazardous chemicals. Jake urges Finn to not bring the chemicals to Princess Bubblegum, but she opens the door and takes them from Finn and returns to her room.

Jake then tells Finn of the fire she summoned, which alarms Finn. He asked how, which Jake replied "With her brain, I think." The two enter the room where Finn believes Princess Bubblegum is just having private time in the bathroom. Jake looks through the keyhole. Finn states it is "pervy," but Jake makes him look in. They see Princess Bubblegum, now with a demonic form, pouring the chemicals into her bathtub, forming a pool like the Lich's Well of Power. When she starts drinking the liquid, Finn and Jake try to stop her, but she rips the tub off of the floor and drinks the entire concoction, growing as tall as her tower and turning deadly black.

She knocks the boys through the wall into the hallway, and as she begins to attack the Candy Kingdom, Ice King appears and asks "Hey, are you dead or what?" He then explains that he saw the Lich possess Princess Bubblegum with his "Wizard eyes." He then explains that he had not spoken up because "when you have stanky old wizard eyes, sometimes you see things that are real, and other times it's like crazy, crazy, crazy, in your face all the time." He wants to help Finn and Jake, but Finn angrily refuses his assistance, as it was his fault for stalling them while chasing the Lich and for almost killing Princess Bubblegum in the first place.

After telling Ice King to "get stuffed," Finn tries to defeat the possessed Princess Bubblegum with the sweater she gave him, but fails. As Princess Bubblegum attacks Jake, Finn finally accepts Ice King's help. As Finn distracts Princess Bubblegum, the Ice King freezes her from the feet up. The Candy Kingdom rejoices, but their jubilation turns to shock when the frozen Princess Bubblegum statue falls over and shatters. Dr. Ice Cream, Nurse Poundcake, and Doctor Princess attempt to reassemble her but they don't have enough pieces. Nurse Poundcake then reveals to everyone that Princess Bubblegum is alive, but she is now thirteen years old instead of eighteen.

Now Ice King loses interest in her and flies home. Finn remarks that he is thirteen as well. Princess Bubblegum calls him a hero, and the two share a loving embrace. As everyone celebrates, the Snail who freed the Lich is seen waving menacingly in the background, with eyes that glow like the Lich's, which shows that the Lich may return.

Major characters

 * Finn
 * Jake
 * Princess Bubblegum
 * The Lich
 * Ice King

Minor characters

 * Candy People
 * Peppermint Butler
 * Dr. Ice Cream
 * Nurse Poundcake
 * Mr. Cream Puff
 * Dr. Donut
 * Cinnamon Bun
 * Guardians of the Royal Promise
 * Green Gumdrop Dude
 * Doctor Princess
 * Emerald Princess
 * Wildberry Princess
 * Lumpy Space Princess
 * Raggedy Princess
 * Slime Princess
 * Snail

Music

 * "Not Feelin' Good Song"﻿

Trivia

 * In the emergency room at the start of the episode, the heart monitor screen is displaying the first 15 digits of pi.
 * All of the items Princess Bubblegum asks for (bleach, gasoline, lighter fluid, plutonium, and ammonia) are extremely sharp, flammable, explosive, or radioactive.
 * Ice King was holding a cup against the wall, and putting his ear up to it, before Princess Bubblegum (altered form) pushed Finn and Jake through it.

Cultural references

 * When Princess Bubblegum was possessed by the Lich, she spoke with a deeper voice, her skin was pale and she sometimes contorted; this is similar to the 1973 horror movie The Exorcist and the 1987 Looney Tunes Cartoon The Duxorcist.
 * When Ice King ascends into the clouds, the clouds slam together in a style reminicent of several Monty Python sketches, namely God's ascent in The Quest for the Holy Grail.

Production notes

 * This episode and "Mortal Folly" would have been the final episodes of the season prior to the rescheduling of "Heat Signature." The two-part episode is still considered the season two finale by the show's crew.

Episode connections
"Mortal Recoil" marks the first time Adventure Time has had a season-ending cliffhanger, unresolved until Princess Bubblegum's next appearance six episodes later in season three's "Too Young." Since then, season-ending cliffhangers have been the norm: season three's "Incendium" was resolved in the season four opener "Hot to the Touch"; and season four's "The Lich" was resolved in the season five two-part opener "Finn the Human" and "Jake the Dog."