It Came from the Nightosphere

"It Came from the Nightosphere" is the first episode of Adventure Time's second season.

Synopsis
Marceline's evil father goes on a soul-sucking rampage after Finn releases him from the Nightosphere.

Plot
The episode begins with Marceline and Finn hanging out at her evil but tastefully appointed lair. She asks Finn to help her lay down a sweet track, but to remain non-judgmental as to the extremely personal nature of the song. Finn agrees, but upon hearing the song, a mournful tale of parental estrangement and french fry theft, Finn asks Marceline why she doesn't reconcile with her father, as the song suggests is her desire. Marceline explains that not only do they have longstanding difficulties in the father/daughter department, but also that he is trapped in a nightmarish pocket-dimension known as the Nightosphere. The only way to free him is to draw a circle of summoning, douse it with bug milk, and chant a fell incantation in Latin. Finn immediately does so, and reality shudders as the veil between our world and the Nightosphere is torn asunder, granting freedom to the Lord of Evil, Sunderer of Worlds and Extremely Snappy Dresser. After dissuading him from devouring Finn's soul on the spot, he takes Marceline's bass, actually a family heirloom axe which she converted to shred riffs instead of flesh, and stalks off into the night to suck the souls from the hapless denizens of Ooo. Finn rushes to stop him, Marceline in tow to retrieve her beloved bass guitar. Marceline's Father embarks on a cross-country feast of souls, tormenting and draining the life from Fluffy People, Marauders and even the Penguins of the Ice Kingdom, where Gunter impresses the Dark Lord with her evil chops. The Ice King confronts the Unfathomable Dweller Between Worlds, but he shows the poor magic-user a glimpse of his true form, a squamous eldritch horror which would shatter the sanity of lesser men, but which merely causes the Ice King to soil his robe. He tries to recover from his embarrassment by saying that it was done "completely by choice," as he flies away. Marceline and Finn set an ambush in a mountain pass, but an enraged Marceline charges her father to take back her bass. She is soundly defeated, and he continues his grim harvest, consuming even such notable beings as Hot Dog Princess and Lumpy Space Princess, who dove willingly into the mouth of madness because she assumed there was a party within, rather than slow ghastly spiritual disintegration. His additional meals begin to allow him to manifest aspects of his true form, a brain-meltingly hideous creature of alien geometries and pulpy tentacles. Finn, after awkwardly making double entendres while trying to come up with a metaphor for fighting him, charges headlong at the slavering abomination in an attempt to leverage his favorite problem solving tool, violence. He is swatted like an insect. Marceline retrieves her bass and storms off, flustered. Desperate for a diversion, Finn plays the recording they had made earlier of Marceline singing about her father, causing her to blush furiously. Marceline's father assures her that he does indeed love her, and he is sorry for stealing her fries, and they have a tender moment of reconciliation. Finn takes this opportunity to gut him like a pinata, spilling his entrails on the ground and freeing the trapped souls. Though immortal and exceptionally powerful, The Lord of Evil is surprised momentarily, and Finn is able to banish him to the Nightosphere before he regenerates. Marceline is at first angered at Finn for embarrassing her and stabbing her dad, but soon calms down. The two collapse and watch the souls bump into each other. Marceline suddenly asks, "I've been meaning to ask you, what's with that pocket on your shirt?". Finn reveals that Jake is inside his pocket. Jake farts and the show ends.

Characters

 * Finn
 * Jake
 * Marceline
 * Marceline's Father
 * Fuzzy Friends (called "Fluffy people" in this episode)
 * Penguins (including Gunter)
 * Ice King
 * Marauders
 * Rock People
 * Tree People
 * Lumpy Space Princess
 * Zombie Poodle
 * Hot Dog Princess (mentioned)

Trivia

 * This episode previously was titled "Return to Nightosphere" then "Marceline's Dad," and then just "Nightosphere".
 * This is Pen's favorite episode of the second season.
 * According to the Frederator Blog, this episode was not completely finished one week before it aired.
 * This is the first episode storyboarded by Rebecca Sugar, and to commemorate that fact, she made a special drawing.
 * This is the first episode where Jake only receives a minor cameo and has no lines.
 * The smiley face used to open the Nightosphere is a PHIL FACE.
 * The incantation to open the Nightosphere is "MALOSO VOBIS COM ET CUM SPIRITUM" which is Latin and is supposed to roughly translate to "evil be with you and with your spirit."
 * When Finn is making the first portal to the Nightosphere, there is a picture that looks like Marceline and her mom over to the left.
 * This is the first episode where Marceline and Finn were allies.
 * Marceline's sweater resembles the sweater worn by Freddy Kruger, the main villan from the movie "A Nightmare On Elm Street".
 * This is the first time Marceline was shown blushing, and the first time she actually showed emotion other than her mischievious and easy-going nature.
 * When Marceline's Dad shows his true face and Finn was hanging in the tentacles, his sword can be seen stabbed in the top of Marceline's Dad head, despite he didn't draw it at beginning of the fight.
 * When it shows the PHIL FACE absorbing the bug milk, an "M" is carved on each of the two candles.