I'm not entirely sure if there is a widely - known fanfiction specifically with Naruto as Issei's older brother. However, in the world of fanfiction, the possibilities are endless. Some writers might create this scenario to explore how Naruto's ninja skills and values would influence Issei, or how their relationship would change the events in Issei's world.
Yes, there might be such fanfictions out there. The idea of crossing over two very different anime universes like Naruto and High School DxD (where Issei is from) and creating a family - like bond between the characters is an interesting concept that fanfiction writers might explore.
Yes, there might be such fanfictions out there. Fanfiction writers often come up with creative crossovers like this. You can try searching on popular fanfiction websites using relevant keywords like 'Naruto Issei older brother' to find them.
In such a fanfiction, Naruto would probably be the protective older brother. He might use his chakra and jutsu to keep Issei out of trouble. Issei, on the other hand, could introduce Naruto to the concept of Devils and other supernatural elements from his world. There could be epic battles where Naruto's ninjutsu combines with Issei's powers against common enemies. Also, Naruto's philosophy of never giving up could inspire Issei to face his own challenges more bravely.
It could be full of action. Naruto would bring his ninja skills to Issei's world. He might train Issei in combat, much like he trained with Sasuke and others. Their relationship could also be full of brotherly banter and support.
The older brother in the fanfiction might be a character with a tragic past. For example, he could have been experimented on by Orochimaru and gained some strange powers as a result. And he returns to the village later to protect Naruto from the threats that are coming towards him.
One idea could be that Naruto, with his strong sense of justice and loyalty, helps Rias in the supernatural politics of her world. He might use his ninja skills to protect her and her peerage from other devils or threats. For example, when facing a powerful rival devil clan, Naruto's shadow clone jutsu could create a diversion while Rias plans a strategic attack.
Perhaps in this fanfiction, Naruto has to keep his identity a secret from Minato. He could be from an alternate future where things went wrong, and he's there to make sure Minato becomes Hokage and prevents certain disasters. So he has to subtly guide Minato without revealing who he really is.
In a fanfiction where Naruto is Madara's older brother, it could completely change the Naruto universe's dynamics. For example, Naruto's ideals of peace and friendship might have influenced Madara at a young age, preventing him from going down the dark path he did in the original story. Naruto could have taught Madara about the power of bonds, which was something Madara seemed to have lost sight of later in his life. This would lead to a different series of events, perhaps even averting the many wars that took place in the Naruto world.
If Naruto was the older brother of Kushina, it would rewrite a lot of the backstory. For one, Naruto might be the one to introduce Kushina to Minato. He could see Minato's potential and think he would be a good match for his sister. Also, Naruto's skills and abilities could have a different origin. Maybe he learned some things from Kushina or their family that were unique. This would change his fight scenes and how he approaches challenges in the fanfiction. He might also have a different relationship with the Uzumaki clan as a whole, having more of a family - based influence within it.
No. Naruto and Laxus are from two completely different anime universes, Naruto and Fairy Tail respectively. While fanfiction can play around with all sorts of wild ideas, making Naruto Laxus' older brother is not a mainstream or even a common fanfiction concept. It would require a lot of creative world - building to make such a relationship seem plausible. For example, the writer would have to explain how Naruto, with his ninja skills and chakra system, could exist in the world of magic like Fairy Tail and have a family - like connection with Laxus. But as of now, this is not a typical fanfiction scenario.
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.