"Obsidian," the title for the Adventure Time: Distant Lands episode, teases a new chapter in Marceline's story. During Comic Con@Home 2020, the virtual San Diego Comic Con held July 22 to 26, the HBO Max and Cartoon Network Studios Adventure Time panel introduced a new kingdom within the show's universe: the Glass Kingdom. While the first episode of the new miniseries follows BMO (Niki Yang) as he crash lands on the space station The Drift light-years away from the Land of Ooo, the second episode in the series, entitled “Obsidian,” will return to Adventure Time’s traditional setting and explore a kingdom never seen before — as well as Marceline and Bubblegum's relationship.
Within the world of Adventure Time, the Land of Ooo is full of many different kingdoms, all of which relate to a specific material, such as the Candy Kingdom, Ice Kingdom, and Fire Kingdom. While the adventures of Jake (John DiMaggio) and Finn (Jeremy Shada) were concluded back in 2018 during the season 10 finale “Come Along With Me,” Adventure Time: Distant Lands will continue the stories of side characters from the Adventure Time universe in four hour-long specials. While the episode “BMO” ended up being a surprise prequel, with BMO’s adventure meeting Y5 (Glory Curda) at The Drift occurring before the events of Adventure Time, the panel confirmed that the second episode “Obsidian” takes place after the series finale and will center on Princess Bubblegum (Hynden Walch) and Marceline's (Olivia Olson) relationship as a couple.
During the Adventure Time: Distant Lands panel, executive producer Adam Muto broke the news about the new kingdom when the moderator Michaela Dietz asked about the meaning of the "Obsidian" title. “It had a lot to do with the setting because it takes place near a place that we haven’t shown on the show previously called The Glass Kingdom and Obsidian is a type of natural glass,” said Adam Muto, who described the title as a metaphor for the events within the special. “Spiritually, [obsidian] can be protective and you know absorb negativity, but it also can be weaponized as an actual material so it kind of has those elements to it that a lot of the characters within the show are exhibiting in this episode.” Given where things left off between Marceline and Bubblegum in the series finale — not to mention their history within the Adventure Time universe — it's safe to assume that Muto is predominantly referring to them.
Possibly the reason the Glass Kingdom hasn't been introduced before now is because the setting spurs a journey of reflection that's more suitable for a special about Marceline and Bubblegum, two of Adventure Time's more emotionally mature characters. “If you really look at Marceline as a character, her story started way before the Finn and Jake timeline of things, and so she’s gone through, you know, lifetimes of ups and downs with different people and seen them come and go,” said Olson about her character during the panel. “So I think it has put her walls up really really high as far as how much she lets people into her life.” Along with Muto’s description of obsidian having the properties to cleanse, draw out stress, and expose things, the special will likely show how Marceline works through some of her issues before she can strengthen her romance with Bubblegum.
While not a lot of specifics about the Glass Kingdom are divulged during the panel, it appears to function like the other kingdoms previously seen on Adventure Time based on the official artwork for the episode. In the artwork, Marceline and Bubblegum are surrounded by new characters made of glass, resembling citizens from other Adventure Time kingdoms who are made of the material their kingdom is named after. Of the two glass characters that appear in the forefront of the artwork, one of them is introduced as Glassboy, a new character voiced by Dietz, while the second appears to be the princess of the Glass Kingdom, given the gem on her head which resembles the gems of power previously worn by princesses in the series. If the character is a princess, it's likely that the Glass Kingdom is a “princessipality,” a term used by Muto to describe a kingdom ruled by a princess.
While no official release date was announced for the Adventure Time: Distant Lands episode "Obsidian" during the panel, it was confirmed that the additional two episodes in the series, “Wizard City” and “Together Again,” are expected to explore new areas in the Adventure Time universe that, just like the Glass Kingdom, were previously unvisited.