Another theme is friendship. They rely on each other during their adventures. Finn's bravery and Roselinen's intelligence complement each other. They support one another through difficult situations, whether it's facing a powerful enemy or solving a complex puzzle.
Love and relationships can also be a theme. Sometimes it's a budding romantic relationship between Finn and Roselinen. Their interactions show how they care for each other, like Finn always making sure Roselinen is safe during their travels, and Roselinen using her magic to help Finn when he's in trouble.
A fanfiction could be about Finn and Roselinen accidentally stumbling into an alternate dimension. At first, they are confused and a bit scared. Finn tries to find a way back home by using his survival skills. Roselinen studies the strange magic of this new dimension. They meet some strange creatures there, some friendly and some not so much. Finn protects Roselinen from the hostile ones, and Roselinen tries to communicate with the friendly ones to find a way home. After many adventures, they finally figure out a way to return to their own dimension.
One common theme is self - discovery. Finn, as a dragon, has to figure out who he is now and how to fit into the world. Another theme is power and responsibility. With his dragon powers, he has new abilities but also new responsibilities. For example, in many fanfictions, he has to protect the weak or save the Land of Ooo from threats.
One common theme is friendship. Finn and Marceline have a unique friendship that often gets explored in fanfiction. They come from different backgrounds, Finn being a human hero and Marceline a vampire, and how they bridge those differences in their friendship is a popular theme. Another is adventure. Since they live in the Land of Ooo, they often go on wild adventures together in these stories.
The theme of redemption can also be found. If Finn is somehow influenced by the demons in a negative way, he tries to find a way to redeem himself. There are also themes related to the unknown and exploration. The demon world is often a new and mysterious place for Finn to explore, which brings in the theme of discovery.
One common theme is self - discovery. Finn often goes through a process of learning more about himself as he experiences love. Another theme is friendship. Since Finn has so many friends in Adventure Time, his relationships with them are often intertwined with his romantic interests.
One common theme is self - discovery. Since Finn is such a dynamic character in the show, in female Finn fanfiction, she often goes on a journey to figure out who she is in a different gender - swapped context.
The theme of sacrifice is also quite prevalent. Finn may have to sacrifice something, like his own desires or his time with friends, for the sake of his romantic relationship. In many fanfictions, he has to make tough choices between his love and other aspects of his life in Ooo.
One common theme is the exploration of relationships. Finn, being the central character, has to navigate through multiple relationships with different characters in the harem. Another theme is character growth. As Finn deals with the harem, he often grows as a person, learning about different personalities and how to interact with them.
One common theme is innocence. Baby Finn is depicted as pure and untainted by the more complex aspects of the Adventure Time world. For example, in many stories, he approaches dangerous situations without really understanding the full danger.
One common theme is friendship. Finn is all about his friends in the show, and in fanfics, his relationships with Jake, Princess Bubblegum, and others are often explored further. Another theme is self - discovery. Finn is constantly growing and learning about himself, and fanfics often take this aspect and expand on it. For example, in some fanfics, he discovers new powers or abilities that make him question who he really is.