<P> The series has a canonical mythology--or, an overarching plot and backstory--that is expanded upon in various episodes . The backstory involves mainly the Mushroom War, the origin of the series' principal antagonist the Lich, and the backstories of several of the series' principal and recurring characters . Ward has said the details behind the Mushroom War and the series' dark mythology form "a story worth telling", but that he feels the show will "save it and continue to dance around how heavy the back - history of Ooo is". </P> <P> When Ward was developing the series' title sequences, the rough draft version consisted of quick shots and vignettes that were "just sort of crazy (and) nonsensical", which alluded to the show's theme of quirky adventures . These drafts included "the characters...just punching random ghosts and monsters, jumping through anything and everything (and) there were a bunch of atomic bombs at the end of it". Ward later called this version "really silly". He sent the draft to Cartoon Network; they did not like it and wanted something more graphical like the introduction to The Brady Bunch . Inspired by the title sequences of The Simpsons and Pee - wee's Playhouse, Ward developed a new title sequence that featured a panning sweep of the Land of Ooo while a synthesizer note rose slowly until the main theme was played . Ward's draft for this idea was handed to layout animators, who then finalized the timing for the sequence . From there, the sequence evolved; while Ward added "silly character stuff", Patrick McHale focused his attention on the Ice King's shot and gave him a "high school (year) book" smile . The crew also struggled to get the shadows in the shot featuring Marceline correct . After the panning sweep, the sequence cuts to the theme song, which plays while shots of Finn and Jake adventuring are shown . For this part of the sequence, Ward was inspired by the "simple" aspects of the introduction to the 2007 comedy film Superbad . When the theme mentions "Jake the Dog" and "Finn the Human", the characters' names are displayed next to their heads, with a solid color in the background . The sequence was finalized immediately before the series aired . </P> <P> The show's eponymous theme song is sung by Ward, accompanied by a ukulele . It is first heard in the pilot episode; in that version Ward is accompanied by an acoustic guitar . For the version used in the series, Ward sung in a higher register to match with the higher range of the ukulele . The finalized version of the theme song was originally supposed to be a temporary version . Ward said, "I recorded the lyrics for the opening title in the animatics room where we have this little crummy microphone just so that we could add it to the titles and submit it to the network . Later, we tried re-recording it and I didn't like it...I only liked the temp one!" Because the series' finalized theme song was originally recorded as a temp track, ambient noises can be hard throughout . For instance, the sound of Derek Drymon typing can be heard while Jake is walking through the Ice Kingdom . According to Ward, much of the series' music has similar "hiss and grit" because one of the show's original composers, Casey James Basichis, "lives in a pirate ship he's built inside of an apartment (and) you can hear floorboards squeak and lots of other weird sounds". As the show progressed, Basichis's friend Tim Kiefer joined the show as an additional composer . The two now work together on its music . </P> <P> The show's title sequence and theme song have stayed mostly consistent throughout its run, with seven exceptions . During the Fionna and Cake episodes (viz . season three's "Fionna and Cake", season five's "Bad Little Boy", season six's "The Prince Who Wanted Everything", season eight's "Five Short Tables", and season nine's "Fionna and Cake and Fionna") the series runs a different intro sequence that mirrors the original, with the major exception that all the characters are gender - bent, and the theme is sung by former storyboard revisionist Natasha Allegri . Likewise, the intro to the series' three miniseries are each unique: the introduction to the Marceline - centric Stakes (2015) places most of the emphasis on Marceline, and the theme song is sung by Olivia Olson; the introduction to Islands (2017) adopts a nautical theme, highlights the principal characters in the miniseries, and is sung by Jeremy Shada; and the intro to Elements (2017) features imagery reflecting the four primary elements in the Adventure Time universe (that is: fire, ice, slime, and candy) and is sung by Hynden Walch . The introductions to the guest - animated episodes "A Glitch Is a Glitch" and "Food Chain" are each unique, featuring animation courtesy of David OReilly and Masaaki Yuasa, respectively . Finally, the series finale, "Come Along With Me", features an introduction offering viewers a glimpse of future Ooo, one thousand years after Finn and Jake . This intro features the new characters Shermy and Beth, and is sung by the latter (voiced by Willow Smith). </P>

When does the plot of adventure time start