Well, an interesting plot point might be how their different ninja abilities are influenced by their brotherly bond. Since Naruto has the Nine - Tails, he could train Sasuke to better handle his Sharingan. And in terms of the story, when Sasuke is faced with the truth about Itachi, Naruto as his older brother could be there to comfort him and help him make a more rational decision instead of just seeking revenge. There could also be a plot point where the village starts to suspect their relation and how they deal with that suspicion together.
Yes, there are likely some fanfictions with this concept. Fanfiction writers often explore unique relationships and alternate storylines. They might create a scenario where Naruto is Sasuke's older brother to develop different character dynamics, explore new plotlines, and add their own creative twists to the Naruto universe.
Well, a really interesting aspect could be how Naruto's presence as Madara's older brother changes the formation of the ninja clans. Maybe he could have united the Uchiha and Senju clans much earlier, preventing a lot of the bloodshed. Also, Naruto could have passed on his unique jutsu and values to Madara, which would have made Madara a very different character. This would completely change the power dynamics and relationships in the Naruto world. And then there's the idea of how their family history would be rewritten and how that would impact the whole ninja world's history.
One common plot point could be Naruto protecting Anko. Since he is her older brother, he might be very protective of her and step in whenever she is in danger.
The plot could start with Naruto growing up in the Uchiha clan as Sasuke's little brother. He might face discrimination due to being the Jinchuriki, but Sasuke would be protective. They could train together, with Sasuke teaching Naruto some of the Uchiha techniques. Later, when the clan is massacred, Sasuke might be even more determined to get revenge, and Naruto would be by his side, trying to stop him from going down a dark path.
Well, a really interesting plot point can be the power - up of their respective ideologies. Naruto could have a moment where his belief in friendship and the will of fire becomes so strong that it physically manifests as a new form of power. Sasuke might have a similar experience with his ideas of revolution and revenge. This not only makes the battle more intense but also adds a deeper layer to their characters. And what if there are some unexpected elements like a third - party interference from an old enemy of the Hidden Leaf who wants to see both Naruto and Sasuke weakened? That would surely spice things up.
The plot could start with Naruto's arrival in the Fairy Tail world. As Laxus' older brother, he would immediately take on a protective role. He could use his rasengan and other jutsu to fight off enemies that threaten Laxus or the guild. Naruto might also try to bridge the gap between the two different power systems - chakra and magic. Along the way, there could be a lot of character development for both Naruto and Laxus. Laxus could learn about Naruto's past and the struggles he had in his own world, which would inspire him to be a better mage. And Naruto would adapt to the Fairy Tail world, using his skills to help the guild grow and protect it from internal and external threats.
A really interesting plot point could be how Harry, now as Naruto's sister, deals with the Nine - Tailed Fox within Naruto. With his knowledge of dealing with dark forces in his own world, he might approach it in a different way than the ninja in the Naruto world. Maybe he tries to communicate with the fox using some form of magic - influenced telepathy.
One possible plot could be that Naruto, having grown up in a different world, suddenly discovers he has a sister in Erza's world. He travels to her world to protect her. Along the way, he has to learn about the magic in the Fairy Tail world while also teaching Erza some of his ninja skills. They could face a common enemy that threatens both their worlds, and their combined skills would be crucial in the fight.
One possible plot could be that Kyuubi protects Naruto from the very beginning. Instead of being seen as a monster, he's Naruto's brother and uses his power to shield Naruto from the villagers' hatred. Maybe they train together in secret, and Naruto becomes much stronger and more confident earlier in the story.
One interesting plot point could be a different backstory for their rivalry. Maybe in the fanfiction, there's a secret reason that made them enemies even before the events in the original story.