One possible plot could be Naruto protecting Serena from various threats in their world. Since Naruto is known for his determination and strength, he would use his ninja skills to keep Serena safe. Maybe they live in a world where both ninja and other magical elements exist, and Serena has some special power that makes her a target, and Naruto is constantly on guard.
In this fanfiction, perhaps Naruto and Serena are orphans. Naruto, being the older brother, takes on the role of a parent - like figure for Serena. He works hard to provide for them both, while also training to become a stronger ninja. Serena, on the other hand, might be interested in the medical side of the ninja world and wants to be a healer. Naruto supports her dreams while also protecting her from those who might try to stop her from achieving it.
Their relationship could also have a bit of a fun side. Naruto might play pranks on Serena sometimes, but in a harmless way. And Serena would get back at him in her own cute ways. They would have deep conversations too, where Naruto shares his wisdom from his ninja experiences and Serena shares her thoughts about the world around them.
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.
There could be. Fanfiction writers like to explore different 'what - if' scenarios. Since Naruto and Kushina have a strong connection in the original series, some writers might be intrigued by the idea of reversing their relationship in a fictional context. But it goes against the established lore of the main Naruto storyline.
In some fanfictions, it's possible for Naruto to be depicted as Anko's older brother. Fanfiction often takes creative liberties with established characters and their relationships.
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.
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 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.
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.
In the fanfiction, the older brother could change Naruto's view of his family and his place in the world. Naruto would have a connection to his past that he didn't know before. This could lead him to explore more about the Uzumaki clan and discover hidden powers or knowledge. And it could also affect his relationships with Sasuke and Sakura. For instance, his brother could help him understand Sasuke's pain better, leading to a different dynamic between them.
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.