He could be a powerful and respected shinobi from the Uzumaki clan. Given the Uzumaki's reputation for strong chakra and unique abilities, Naruto's grandfather might have been a key figure in the clan's history.
Well, it's quite possible. Fanfiction writers are known for their wild and creative ideas. Since both Naruto and Natsu are from popular anime, some writer might have thought of creating a story where Naruto is somehow related as Natsu's grandfather. But it also depends on how much of the respective anime universes the writer wants to blend and how they would explain such a connection in the story.
It could be an old and powerful wizard who has been in hiding for years. Maybe he was a friend of Dumbledore's but had some differences with him, so he stayed away from the main events in Harry's life until now.
Yes, in many fanfictions, Hashirama is often depicted as Naruto's grandfather. Fanfiction writers like to create such family relationships to add new storylines and depth to the Naruto universe. It can lead to interesting plot developments, such as Naruto inheriting some of Hashirama's unique abilities or having a closer connection to the founding of the Hidden Leaf Village.
One idea could be that Naruto's grandfather was a great shinobi who had a unique jutsu that was lost over time. In the fanfiction, Naruto could discover some hidden scrolls that lead him to learn about this jutsu from his grandfather's past.
Yes, in certain fanfictions Jiraiya is indeed Naruto's grandfather. This alteration of the original Naruto storyline in fanfiction can create a whole new set of character dynamics. For example, it could mean that Jiraiya had a more direct role in Naruto's family history. It might also change how Naruto views his own family and his place in the ninja world. This kind of creative change in fanfiction can bring fresh perspectives to the well - known Naruto story.
One possible plot could be that Naruto, through some magical or time - traveling event, ends up in the world of Natsu. He then becomes an important figure in Natsu's family, eventually becoming his grandfather. He could pass on his ninja skills and values to Natsu, which would make Natsu a more powerful and wise mage.
His grandfather could be a very wise and patient man. He might have been the kind of person who was always calm in the face of danger, and Naruto could inherit some of these traits subconsciously.
In fanfiction, the possibilities are endless. Regarding Madara Uchiha being Naruto's grandfather, it could be a really cool and unique take. Maybe the fanfic writer has a great plot in mind where this relationship changes the whole Naruto story. For example, it could influence Naruto's powers, his understanding of the Uchiha clan, or even how he views the history of the ninja world. But of course, this is just a fanfiction idea and has no basis in the original Naruto plot.