Naruto's life would be filled with new experiences. He'd have to learn how to be a role model. This means not just showing off his ninja skills, but also teaching his brother about values like honesty and loyalty. He'd also have to deal with his brother's emotions. For instance, if his brother gets bullied, Naruto would need to step in and handle the situation in a way that both protects his brother and teaches him how to stand up for himself. And he might start to see the village in a different light, as he now has a family member to look after and wants to make the village a better place for his brother to grow up in.
Naruto's life would change a great deal. He would no longer be alone growing up. There would be someone who truly understands him on a deeper level. They could train together, and Naruto might learn new techniques from his twin. Also, the villagers' perception of Naruto might change as they compare him to his twin. Maybe his twin is more well - behaved, which could either make Naruto feel pressured to be better or resentful.
Well, in such a fanfiction, Naruto might be very protective of his little brother. He could introduce his brother to all his friends, like Sakura and Sasuke. His brother might struggle with the same kind of loneliness Naruto once felt, but Naruto would be there to support him, ensuring he doesn't go through the same hardships he did. And they could train together to become strong ninjas.
Naruto's training would likely be more focused on Senju - style techniques. Tsunade could teach him some of the more advanced medical ninjutsu that she knows. This would make Naruto not only a strong fighter but also a healer, which would be a huge advantage in battles.
He would become more responsible. He has to take care of another person now, so he can't be as reckless as he sometimes was. For example, he'd think twice before running into danger because he has his sister to consider.
His abilities might be enhanced by the demonic powers associated with Sirzechs' world. For example, his Rasengan could take on a more demonic form, with added destructive power. Maybe he could also gain the ability to teleport short distances like some demons in Sirzechs' world, which would give him an edge in combat.
Naruto might become more confident earlier. With a brother by his side, he would have someone to rely on and confide in from the start. This could make him less of an outcast in his own mind and more willing to open up to others in the village.
Naruto may become more confident. By raising his hand, he's taking initiative, which is a sign of growing self - assurance. He's no longer waiting for others to pick him or tell him what to do.
Their relationship would change in many ways. Firstly, Naruto would be more involved in Gaara's life. He would probably train with Gaara more often, teaching him new techniques. Secondly, Naruto would be a source of emotional support for Gaara. Given Naruto's positive attitude, he could help Gaara overcome his past traumas more effectively. And finally, they would have a stronger sense of loyalty towards each other. In battles, Naruto would not hesitate to put himself in harm's way to protect Gaara, and Gaara would do the same for Naruto, much like a real - life brotherly relationship.
Obito's influence would likely make Naruto more aware of the darker side of the ninja world. Naruto is usually very optimistic, but with Obito's guidance, he would see the hardships and betrayals that can happen. For example, Naruto might become more cautious in his trust of others.
Naruto would likely become more disciplined. Kakashi is known for his strictness, so Naruto would have to follow a more structured training regime. This would make him more focused during battles and in his studies of ninjutsu.