Maybe Naruto gets wounded in an ambush set by a group of rogue ninjas. As he's wounded, he's captured and has to find a way to escape while being injured. His captors could be after the Nine - Tails' power. Meanwhile, his friends and allies start a search mission to find him. During his captivity, Naruto could meet other prisoners who have their own stories and motives, which could influence his view on the ninja world.
One idea could be that Naruto gets wounded while protecting the village from a new and powerful enemy. This could lead to other characters having to step up in his absence, like Sakura taking on more medical and combat responsibilities to keep the village safe while Naruto recovers. Another plot could involve Naruto getting wounded during a solo mission and having to rely on his own survival skills and inner strength to make it back to the village. It could also show his journey of self - discovery during his recovery as he reflects on his past battles and losses.
A plot could be that Naruto gets wounded by a long - thought - dead enemy who has returned with a vengeance. His friends then search for a rare herb or a special medical technique to heal him. In the process, they face many challenges and also learn more about Naruto's importance to the village and to each other. Or perhaps Naruto gets wounded in a friendly spar with Sasuke that goes wrong. This could lead to a rift between them again, and they have to work through their issues while Naruto heals.
Maybe in the fanfiction, Naruto gets the Rinnegan as a result of a genetic experiment gone wrong (but in a good way). His Uzumaki genes combined with some unknown factor from an enemy he defeated. With the Rinnegan, he could unlock new jutsu that blend his already powerful Rasengan and shadow clone techniques with the abilities of the Rinnegan, like the ability to control gravity.
One plot idea could be that Naruto is on a mission and stumbles upon an ancient Uchiha artifact that somehow bestows the Sharingan upon him. He then has to quickly learn to control it while his friends are both amazed and a bit wary. Another could be that during a battle with an unknown enemy who has the power to transfer abilities, Naruto ends up with the Sharingan. This leads to him exploring the new abilities in unique ways, like combining Rasengan with Sharingan - enhanced perception.
One plot idea could be that Naruto needs Tsunade's medical expertise for a mission. He has to convince her to join him, and during their journey, Tsunade starts to see Naruto in a new light, not just as a rowdy kid but as a capable ninja. Another idea is that Naruto discovers a hidden secret about Tsunade's past and helps her come to terms with it, which deepens their bond.
One interesting plot idea could be a story that focuses on their wedding preparations. It could show how Naruto, who is not used to all the formalities, struggles with choosing the right wedding kimono or learning the proper wedding etiquette. Hinata, on the other hand, is more in tune with the traditional aspects but is nervous about becoming the wife of the Hokage. Another idea could be a time - travel fanfic where they go back in time to their first meetings and relive those moments with the knowledge of their future together. It would be a chance for them to see how far they've come and how their relationship has developed over the years.
A possible plot is that when Naruto is de - aged, he forgets some of his later - learned ninja techniques. So he has to start from scratch and relearn them in a different way. This could lead to him developing new and improved versions of those techniques. Also, the de - aging could be part of a villain's plot. Naruto then has to figure out how to reverse it while also dealing with the chaos that his sudden change in age has caused in the village, like how his friends now have to protect him instead of the other way around.
One idea could be a story where Naruto and Temari are arranged to be married for political reasons between Konoha and Suna. At first, they're both a bit hesitant, but as they start to spend time together, they discover they have more in common than they thought. For example, they both have a strong sense of duty to their villages. Another plot could involve a threat to both villages that forces them to marry quickly to show unity, and during their relationship's development, they learn to trust each other and combine their unique ninja skills to protect their homes.
One plot idea could be that Naruto discovers an ancient scroll that reveals a way to obtain the Rinne Sharingan. This new power then causes a rift in the ninja world as some fear his newfound strength while others see it as a way to finally achieve peace. He has to struggle with mastering this power while also dealing with the political implications.
Perhaps Naruto gets the Sharingan in a different dimension where he has to adapt to this new power. He could face challenges like being hunted by those who want to steal the Sharingan from him. He might also discover new abilities within the Sharingan that are unique to him because he's not a pure - blooded Uchiha. For example, he could use the Sharingan to enhance his Sage Mode, seeing things more clearly and predicting attacks better.
One plot idea could be a time - travel fanfic. Naruto, Sakura and Hinata are sent back in time to their childhood days. They remember their future lives where they got married. This knowledge makes them act differently. Naruto tries to avoid some of the mistakes he made in the past. Sakura focuses more on her medical ninjutsu from a young age. Hinata works on her confidence even earlier. Eventually, they still end up getting married in a more perfect way than in the original future they knew.
One idea could be a story that focuses on their wedding preparations. It could show how Naruto is clueless about most of the traditional wedding stuff in the Hyuga clan, and Hinata has to patiently explain it to him. Another plot could be set after their marriage, where they face challenges in balancing their ninja duties and family life. For example, a mission comes up that might take Naruto away for a long time right after their honeymoon, and they have to figure out how to deal with it as a newlywed couple.