Well, in some fanfictions, there could be a plot where Marceline's dad comes back to make amends for his past wrongdoings. He might try to reconnect with Marceline by helping her out in a tough situation, like when she's facing a really powerful enemy. It could also be interesting to see a story where Marceline's dad reveals some long - held family secrets that change how Marceline views herself and her powers.
One interesting plot idea could be Jake and Marceline teaming up to explore a new, mysterious part of the Land of Ooo. Maybe they find an ancient relic that has the power to change the world. Another idea is that they get caught in a time - loop and have to figure out how to break it while dealing with their own personal issues.
One idea could be Marceline and Finn teaming up to explore a new and mysterious part of the Land of Ooo. They could encounter a powerful and ancient magic that they have to figure out how to control. Another plot could be Finn trying to help Marceline reconnect with a long - lost friend from her past. Maybe there's a feud between this friend and Marceline that Finn has to mediate.
One idea could be that PB accidentally creates a magical device that swaps their personalities. Marceline then has to deal with being super sweet and girly while PB tries to maintain her tough rocker image. It would lead to a lot of comical situations as they try to navigate their daily lives in each other's shoes.
Probably Finn and Jake. Since they are Marceline's friends in the original Adventure Time, they often show up in fanfictions related to Marceline's dad. They might be there to support Marceline during her encounters with her dad, or they could be involved in some sort of adventure that is related to her dad's past actions.
A really interesting plot could be set in an alternate dimension where Ice King is a normal king and Marceline is a human. They meet in this new world and have to figure out how to get back to their own world while also dealing with the new relationships and challenges this world presents. They might discover that their bond is stronger than they thought, even in these different forms.
Another interesting fanfic idea is that Marceline loses her vampiric powers and Marshall Lee has to help her adapt to a more 'human' or at least non - vampiric life. This would lead to a lot of character development as Marceline struggles with her new identity and Marshall Lee learns more about her true self beyond her powers.
One interesting fanfiction could be about Marceline and Bubblegum going on a quest together to save the Candy Kingdom from a new, mysterious threat. In this story, their relationship could be explored more deeply as they face challenges side by side.
One interesting fanfiction could be about Finn and Marceline going on a quest to find a lost magical artifact. In this story, they might face various challenges together, like dealing with strange creatures and solving puzzles. Their different personalities, Finn's optimism and Marceline's cool - headedness, would make for an engaging dynamic.
There are fanfictions where Bubblegum and Marceline have a sort of time - traveling adventure. They could end up in different eras of the Adventure Time universe, like the pre - Mushroom War world, and have to find their way back while also learning more about each other's pasts. It's really cool to see how their relationship develops in these different settings.
Marceline is a vampire, so her immortality is an interesting trait. It gives her a long - term perspective on things in the Land of Ooo. She's also an amazing musician, with her bass guitar skills being top - notch. Her ability to fly and her super strength, which come with being a vampire, are also cool. And she has a complex personality, being both tough and having a soft side, especially when it comes to her relationships with characters like Finn and Jake.