One interesting storyline could be about Naruto and his siblings training together secretly. They might discover new jutsus that are unique to their family line. This would not only strengthen their bond but also make them a formidable force in the ninja world.
In some fanfictions, Naruto's siblings could be from a different village. They come to Konoha to find Naruto, and there's a whole drama of acceptance and dealing with the differences between the villages. It could involve political intrigue as well as personal growth for all the characters.
One popular storyline could be the siblings coming together to face a new, powerful enemy that threatens the Hidden Leaf Village. They might combine their unique skills, like Naruto's Rasengan and a sibling's special jutsu, to save the day.
One interesting storyline could be them protecting each other from supernatural threats in their world. Since they are siblings, they would have a strong bond and would go to great lengths to keep each other safe.
One interesting storyline could be the twin having a unique ninja ability that Naruto doesn't have. For example, the twin might be able to control water in a way that no one else in the village can. This could lead to them being trained by a different master, perhaps someone who specializes in water jutsu. Another storyline could be the twin getting involved in a different prophecy than Naruto. Instead of being the one to save the village from a certain threat like Naruto, the twin could be fated to deal with an internal conflict within the ninja clans. And finally, the twin could have a different relationship with Sasuke. Maybe they are friends from the start and their friendship has an impact on how Naruto and Sasuke's relationship develops over time.
In this fanfiction, the hidden blade could be a cursed object that Naruto initially doesn't realize. As he starts using it, strange things begin to happen. He might start having visions or losing control of his chakra at times. However, with the help of his friends like Sasuke and Sakura, he tries to figure out the origin of the blade and how to break the curse. They might research in old ninja scrolls or consult with wise elders in the village to find a solution.
Another storyline might involve Naruto's family expanding. They could adopt orphans from the war-torn areas of the ninja world. This would show their big - heartedness and also bring new dynamics to the family as they integrate these new members.
A cool fanfiction storyline might involve Naruto with the Hiraishin bloodline teaming up with other powerful ninja in the world. They could form a special unit that uses their combined abilities to take on the toughest threats. For example, Naruto could use his Hiraishin to quickly transport the team to different battlefields, allowing them to fight more effectively. Or, Naruto could discover that the Hiraishin bloodline has a deeper connection to the Sage of Six Paths, and he has to embark on a journey to fully understand and master this connection.
Some fanfictions might explore the domestic side of Naruto having multiple wives. How does he balance his time and love among them? There could be cute and humorous scenes like Naruto trying to remember the birthdays and preferences of all his wives. Also, the story could involve how the different wives interact with each other, whether they become friends or have some friendly rivalries within the household.
One interesting storyline could be Naruto using the Sharingan to copy the magic of Fairy Tail wizards. He could then combine his ninja skills with the copied magic, creating unique fighting styles. For example, he might copy Erza's requip magic and use it to quickly change his ninja tools during battle.
One interesting storyline could be Naruto using the takeover magic to assume the powers of different powerful ninja. For example, he might take over the Sharingan abilities from an Uchiha. This would create a whole new dynamic in battles and his relationships with other characters.
In some fanfictions, Naruto's prosthetic limbs could be a result of a super powerful enemy attack that almost killed him. But instead of being defeated, he rises stronger. The limbs could be made from some rare and magical materials in the Naruto universe, like chakra - infused metals. This gives him new powers and abilities that he has to learn to control, leading to exciting adventures.