One interesting plot could be traveling back to the dinosaur era. Imagine being able to witness those gigantic creatures up close, running from a T - Rex. Another could be traveling to the future to see how advanced technology has become, like flying cars and buildings that touch the sky. Or perhaps traveling back to a significant historical event and trying to change the outcome for the better.
In a time travel adventure story, a great plot might be about a character accidentally traveling to different time periods while trying to fix a time - traveling device. They end up in the middle of a medieval battle one moment, and then in a 1920s speakeasy the next. They have to figure out how to get home while also dealing with the challenges of each era.
One possible interesting plot could be about changing a historical event and dealing with the unforeseen consequences. For example, a character might go back in time to prevent a war, but then realizes that this action led to other negative outcomes like economic collapse.
One interesting plot could be Fionna and Cake going on a quest to save their world from a new, mysterious dark force. They might encounter strange new creatures and have to use their wits and friendship to overcome challenges.
One interesting plot could be that Naruto somehow ends up in the Adventure Time universe and attracts a harem of the unique characters there. Maybe he uses his ninja skills to protect them from the various threats in Ooo, like the Ice King. And as he spends more time there, different characters start to develop feelings for him.
A really cool plot might be the origin story of the 'Burning Low' event in the fanfiction. It could involve an ancient magic or a long - forgotten prophecy that sets the whole dangerous situation in motion. Maybe it was an accident caused by an old wizard that lived in the Land of Ooo long ago.
One interesting plot could be the discovery of a new type of gum with extraordinary powers in the Gum War. This new gum might change the balance of power between the different factions. Another plot could involve a character from the original Adventure Time series getting caught in the middle of the Gum War and having to use their unique skills to survive.
One interesting plot could be a character going back in time to prevent a certain card from being created, which then changes the whole Yu - Gi - Oh! tournament scene. For example, if the Blue - Eyes White Dragon card was never created, how would the power balance shift among duelists?
One interesting plot could be Superman traveling back in time to prevent the destruction of Krypton. He could use his powers to stop the cataclysmic events that led to its downfall. Maybe he tries to convince the Kryptonian council of the impending danger, but faces resistance as they don't believe him at first.
One interesting plot could be Ben traveling back in time to meet his younger self and having to hide his identity while trying to prevent a future disaster that his younger self unknowingly causes.
Another plot could be that they travel to a future time where music has evolved into something completely different. They struggle to understand the new forms of music but also bring back some of the old charm from their time, creating a unique blend that revolutionizes the future music scene.
Another plot might be Kratos traveling to a time in the future of his own world. He could see the consequences of his actions and how the world has changed. Maybe he discovers that his actions have led to a new threat emerging, and he has to figure out how to fix it. This would add a new layer of responsibility to his character.