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 the clash of cultures. Naruto comes from a world of ninjas and strict training, while Adventure Time has its own very different and often wacky culture. Fanfictions often explore how Naruto adapts to this new world and how the characters from Adventure Time react to his presence.
One popular Finn Adventure Time harem fanfiction is 'Finn's Multiple Journeys'. It explores Finn having different adventures with multiple characters in a harem - like scenario. Another is 'Finn and His Friends in a New World' which also has elements of a harem concept with Finn interacting in unique ways with various characters from the Adventure Time universe.
Of course, some original Uchiha characters like Mikoto Uchiha. She was Itachi and Sasuke's mother. In a time - travel fanfiction, Naruto could interact with her in a way that changes the course of history. Maybe he saves her life, and she feels indebted to him, leading to her being part of his harem. Her motherly instincts could also be a factor in how she interacts with Naruto and the other members of the harem.
One idea could be that Naruto and Finn the Human accidentally cross paths in a strange dimension. Naruto could be on a mission to find a new type of chakra source and Finn is exploring the unknown. They initially misunderstand each other and fight. But then they realize they both have a strong sense of justice and team up to defeat an evil force that threatens both their worlds.
Another good one is 'When Naruto Met Marceline'. This fanfiction focuses on the encounter between Naruto and Marceline. Their personalities clash and mesh in interesting ways. The author does a great job of showing how Naruto's positive, can - do attitude affects Marceline, and how her more laid - back, but powerful vampire self influences Naruto. It's full of action, humor, and some really heartwarming moments.
One popular plot is the main character traveling back in time to change certain events in the Naruto world and ending up with a harem. For example, they might prevent a major battle and in the process, gain the affection of multiple female characters like Sakura, Hinata, and Ino. Another plot could be that the time - traveler has some special knowledge from the future that makes them very attractive to the characters around them, leading to a harem situation.
Temari is often seen in these fanfictions. Given her strength and independent nature, she can be a great addition to the harem. The time - traveler might encounter her during some important events and form a bond with her. Tenten is also a common character. Her skills with weapons and her determination can attract the time - traveler. They could train together or the time - traveler could help her achieve greater things, leading to her being part of the harem. And of course, there's also Anko. Her unique personality and her skills as a ninja can make her an appealing character in the context of a time travel Naruto harem fanfiction.
In a Naruto pranks Hyuuga fanfiction, Naruto might use his typical mischievous tactics. For example, he could use his shadow clone jutsu to create chaos around the Hyuuga compound. Maybe he'd make clones that pretend to be important visitors and then act all silly to embarrass the Hyuuga. It would be a really funny scenario as the serious Hyuuga clan tries to deal with Naruto's antics.
One possible fanfiction could be about Naruto characters finding themselves in the Avatar world. For example, Naruto's determination and never - give - up attitude could be a great addition to the Avatar universe. He might learn bending techniques in a unique way, perhaps by combining his chakra control with the flow of chi in the Avatar world. This could lead to some really interesting battles and character interactions.