He could be very protective. Since he's taking in Naruto, he would want to keep him safe from all the harm that Naruto has faced in the original story. Maybe he's also a bit of a loner, which is why he can understand Naruto's feelings of isolation.
One possible plotline could be Naruto growing up with his uncle and learning different jutsu from him. His uncle might have a unique style of teaching that helps Naruto develop his skills faster. Maybe his uncle also has some secrets about Naruto's family that he gradually reveals as Naruto gets older.
One possible character trait is self - sacrifice. He would be willing to put himself in danger for Naruto's sake. He could also be patient. Naruto can be a bit impulsive, so an older brother would need to be patient with him. He might be a bit of an outcast too, like Naruto was in the village. But instead of being shunned for having the Nine - Tails, he could be shunned for some other reason, like having a different ideology about how the ninja world should be run. This would add depth to his character and his relationship with Naruto.
Well, the plot could start with Naruto discovering this family connection. Maybe he finds some old documents or a hidden message. Then, Nagato could take Naruto under his wing and teach him some of his powerful jutsu. This would make Naruto even stronger and change the way his friends and enemies view him.
She could be very strong - willed, much like Naruto. Since she has grown up without her family, she has had to be tough to survive. Maybe she is also very curious about her past and her brother, which drives her to seek out the truth.
Yes, there might be such fanfictions out there. Fanfiction writers often come up with unique family relationships for characters. In the Naruto universe, while it's not part of the official story, in fan-created works, Nagato could potentially be written as Naruto's uncle. This could add interesting twists to the plot, like exploring how Nagato's past and his connection to Naruto's family might change the way Naruto grows up or views the world.
He might be empathetic. Fem Naruto is known for her big heart and ability to understand others. The son could inherit this trait and be someone who tries to see the good in everyone, even his enemies. However, he could also have a bit of Sasuke's aloofness at times, making him a complex character. He may keep his distance from others until he truly gets to know them, but once he does, he's a loyal friend.
The demon uncle could make Naruto more accepting of differences. Since he's a demon, Naruto would learn not to judge based on appearance or origin. This could make him a more well - rounded and empathetic character.
They could go on a quest to find a powerful artifact that has the potential to destroy both their worlds. Bruce's detective skills and Percy's demigod powers would make them a formidable team. For example, they might have to search for an ancient Atlantean relic that has been corrupted by dark magic.
They could have an adventure in the world of the gods together. Tony, with his scientific knowledge, might try to understand the magic of the gods, and Percy could show him around the places like Mount Olympus. Maybe they would have to team up to stop a powerful enemy that threatens both the mortal world and the world of the gods.
Naruto could pass on his determination. He's always been someone who doesn't give up easily, and Minato might inherit that. Also, his loyalty. Naruto is extremely loyal to his friends and the village, and Minato could grow up with those values. Maybe even Naruto's love for ramen would be passed on in some comical way.