One interesting plot could be the female jinchuuriki having to team up with Naruto to protect their village from a powerful new threat. As they work together, feelings start to develop among them in the harem setting.
Well, in some of these fanfictions, there might be a plot where the female jinchuuriki are from different villages and they all come together around Naruto. They have to overcome their differences and prejudices while also dealing with their growing affection for Naruto. For example, they might have to fight against an organization that wants to capture all the jinchuuriki, and in the process, their relationships with Naruto and with each other deepen.
One of the popular ones is probably Kushina, Naruto's mother. Since she was a jinchuuriki herself, she often appears in these fanfictions in the harem. Another could be Fu from Takigakure.
Perhaps a plot where they are raised together in a hidden village that has its own secrets regarding the jinchuuriki. They grow up with a sense of camaraderie and together face threats from outside forces who want to capture or use their power. This could lead to epic battles where they combine their abilities in unexpected ways.
One interesting plot could be the Naruto characters interacting with Hollow characters in a unique way. For example, Naruto might use his ninja skills to help the Hollows deal with some internal conflicts in their world. Maybe they team up to fight a common enemy that threatens both the ninja world and the Hollow realm.
One interesting plot could be where Naruto has to navigate his relationships with multiple female characters in unique ways. For example, he might go on special missions with each of them, leading to character development and deeper bonds.
One interesting plot could be that Naruto and Sonic find themselves in a strange new world where they have to protect a group of female characters from a common enemy. As they do this, they form deep bonds with these characters, leading to a harem - like situation.
One interesting plot could be how Naruto manages the different personalities in his harem. For example, dealing with a strong - willed kunoichi who might clash with a more gentle - natured girl in the harem. Another plot could be the challenges they face as a married group, like how they handle family traditions from different clans.
Perhaps a plot where the female Kyuubi characters all have different powers and abilities, and Naruto has to figure out how to work with each of them. This could lead to some really cool fight scenes where Naruto and the female Kyuubi use their combined powers to defeat a common enemy. It also shows how they complement each other in the harem setting.
One interesting plot could be Naruto being banished and then gradually forming a strong bond with the female characters in the harem. As he overcomes his feelings of rejection from his village, he discovers new powers and relationships. For example, he might learn new jutsu from one of the female characters who has a unique family technique. This would not only make him stronger but also deepen their connection.
Well, a plot might be that Dark Naruto in the fanfiction is on a journey to change the ninja world with his harem by his side. They could be facing off against the established shinobi villages' old ways. For example, they might try to create a new system where power is more equally distributed among all ninjas, not just the elite families. And the harem members could each have special skills that contribute to this goal.
Well, sometimes in these fanfictions, there's a plot where Naruto has to protect Hanabi and the other members of the harem. Maybe there's a new threat to the village and Naruto's harem becomes a sort of team. Hanabi might be the one who initially challenges Naruto's leadership in this group but then gradually comes to respect and support him. And along the way, there are the typical romantic sub - plots as Naruto tries to balance his relationships with everyone in the harem.