One idea could be that Naruto has an innate ability to control the Sharingan more effectively than Sasuke. Since he's a descendant of Madara, his chakra might be more attuned to the Uchiha powers. This could lead to new jutsu combinations, like mixing the Rasengan with some form of Sharingan - enhanced fire style. It would also create a whole new dynamic in his relationship with Sasuke, as Sasuke would have to come to terms with Naruto having a stronger connection to the Uchiha heritage than he does.
They could go on adventures to discover ancient ninja secrets. Since they are the same age, they might team up to explore hidden places that are said to hold great power or knowledge. Maybe they would search for lost jutsu together and face various challenges along the way.
Some fanfictions might depict Naruto as having a deeper understanding of the chakra system than ever before. He could have found a way to disrupt Madara's connection to the chakra source, or maybe he was able to use his own chakra in a way that nullified Madara's powerful jutsus. Also, Naruto's experience from all his previous battles might have led him to anticipate Madara's moves and strategies, allowing him to stay one step ahead and ultimately defeat him.
Well, in such a fanfiction, it might start with Naruto being in a situation where he becomes Madara's pet. Maybe at first, Naruto is defiant but as time passes, he could start to understand Madara's motives in some strange way. Madara, on the other hand, might initially see Naruto as just a possession but gradually develop a sense of attachment. It could be a really strange and complex relationship that unfolds as the story progresses.
Well, it could have a plot where the protagonist, as the heir of Madara, tries to reshape the ninja world according to Madara's unfulfilled ideals. Maybe they strive to unite all the ninja clans under a new order.
A good Naruto fanfiction with Madara often has a well - developed plot. For example, if it explores his motives in a new way. In the original, Madara had certain goals like creating the Infinite Tsukuyomi. A fanfiction could expand on why he really wanted that and what else he could have done. Also, a good one gives Madara more depth as a character. Maybe it shows his softer side or his regrets. Good character development for Madara and the other characters around him is key. If it can make the reader understand Madara better, it's a great fanfiction.
On a broader scale, the ninja world would enter a new era. The threat that Madara posed would be eliminated, and Naruto would likely have a major role in shaping the new world order. He might focus on peace - building initiatives and forging stronger bonds between the different ninja villages.
The plot could involve Naruto studying Madara's old techniques and strategies. He might be fascinated by Madara's ability to control the Nine - Tails in the past. So, Naruto starts to dig deeper into Madara's history and teachings, trying to incorporate some of his ideas into his own ninja way while still maintaining his core values.
It could completely change Naruto's character and abilities. Madara's teachings might lead Naruto down a darker path or give him incredibly powerful skills.
Sasuke is often a popular character in these fanfictions. He might play a role in helping Naruto against Madara or have his own motives during their battle. Kakashi can also be a prominent figure, perhaps using his Sharingan in a crucial moment to assist Naruto. Another popular character could be Hashirama, as his connection to Madara is a key part of the original story and can be further explored in fanfiction.