Well, in such a fanfiction, Madara's training might enhance Naruto's physical strength. He could teach Naruto some advanced Uchiha techniques which Naruto can combine with his own Uzumaki powers. For example, Naruto might learn better chakra control from Madara, enabling him to use his Rasengan more effectively and with less chakra waste.
Often, Naruto might be paired with Madara in some sense. Their opposing views on power and peace could create interesting interactions in the fanfiction.
Madara's Sharingan would be a very unique ability in the Harry Potter world. It could be used for things like detecting lies, seeing through invisibility spells that are not as advanced as the Sharingan's capabilities, and predicting an opponent's moves in duels. His ability to use fire - based jutsu could be seen as a form of very powerful and different magic. Also, his physical combat skills would make him a formidable opponent in a world where most rely on wands for combat.
One possible fanfiction could be about a young ninja who discovers he has a special connection to Madara's Sharingan. Maybe he inherits some of Madara's latent powers through a mysterious family link. This could lead to him being hunted by those who want to use his power for evil or by those who fear it.
He could gain the ability to predict his opponents' moves more accurately. The Sharingan is famous for that. So Naruto would be even better at dodging attacks in combat.
Naruto would likely have enhanced Sharingan abilities. He could potentially skip some of the normal progression steps of the Sharingan and quickly reach advanced levels like the Mangekyo Sharingan. His physical abilities might also be enhanced due to the Uchiha bloodline. Maybe he would have better reflexes and speed. Also, he could inherit some of Madara's unique jutsu or at least have an easier time learning similar ones.
No. Naruto has his own unique story and character development that is distinct from simply being a fanfiction of Uchiha Madara. Naruto is about his journey to become Hokage, his relationships with his friends like Sasuke, Sakura, etc. His goal is to bring peace to the ninja world in his own way, through understanding and friendship. While Madara is an important part of the Naruto lore, Naruto's story is not centered around being a fanfiction of Madara. He is his own hero with his own dreams and challenges that are not directly related to being a fan of Madara.
Yes, there might be. The world of fanfiction is vast and full of crossovers. Fans often like to combine different fictional universes, so it's very possible that someone has created a story where Harry Potter is a fan of Madara Uchiha. You can search on various fanfiction platforms to find out.
In some fanfictions, it could be through a divine intervention by Kami. Maybe Kami sees Naruto's pure heart and his need for more power to protect the village. So, Kami decides to bestow upon Naruto the power of Madara's Sharingan as a way to give him an edge in battles against powerful foes.
Well, if Naruto were Madara's brother in a fanfiction, it would completely change the Naruto universe. Their power levels combined could make them an unbeatable force. Naruto's positive attitude might have influenced Madara to not go down the dark path he did in the original story. It could also lead to different alliances and battles, with Naruto perhaps trying to reason with Madara and change his view of the ninja world.