He could be a very powerful mage, perhaps even more powerful than Erza in some aspects. For example, he might have a unique form of magic that is rare in the Fairy Tail universe, like the ability to control time on a small scale. This would make him a valuable asset in battles and also a target for enemies who want to use his power for their own evil purposes.
He could be a very mysterious character. Maybe he has a past that is full of secrets and dark deeds that he is trying to atone for. In the fanfiction, his relationship with Erza could be complex, as he wants to protect her from his own past while also trying to become a better person. He might be constantly haunted by his past mistakes and use his relationship with Erza as a motivation to change.
They could have adventures where they combine their skills. Naruto could use his ninja techniques like shadow clones, and Erza could use her different armors and magic. For example, they might fight against a powerful enemy that is a threat to both their worlds. Naruto's clones could distract the enemy while Erza changes into her strongest armor to deliver a powerful blow.
Naruto might gain the ability to use magic weapons like Erza. Since he's a quick learner, he could master the use of different magical swords or armors. He could infuse his chakra into these weapons to make them even more powerful. For instance, a sword that can cut through any material when combined with his chakra and also has the ability to cast magic spells.
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.
Well, in this fanfiction concept, it could work in terms of Naruto's protective nature. Naruto is known for his loyalty and his will to protect those he cares about. If he were Erza's older brother, he would surely use his skills and abilities to keep her safe. He could teach her some of his ninja techniques, which would be really cool to see combined with Erza's own combat skills. Also, Naruto's positive attitude could influence Erza in a different way, making her more open and perhaps less brooding at times.
Well, Naruto might bring his ninja skills to Erza's world. He could use his shadow clone jutsu to help Erza in battles. Maybe he'd be a bit of a troublemaker at first, not fully understanding the rules of Erza's guild. But over time, he'd grow to respect and adapt to it, using his unique abilities to support Erza and her friends.
Yes, there might be such fanfictions out there. Fanfiction writers often create crossovers between different anime universes, and the idea of Naruto being Erza's brother is an interesting and unique concept that some might explore in their stories.
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.
One common theme is the struggle for identity. Since he's in Erza's shadow, he often has to find his own place. Another theme is family loyalty, as he tries to support Erza and live up to the Scarlet name.
Yes, there are likely some fanfictions out there with such a concept. Fanfiction writers often come up with creative crossovers like this. However, the quality and nature of such fanfictions can vary greatly. Some might focus on how Naruto's ninja skills could influence Erza's world in Fairy Tail, while others could explore the family dynamic between them in an interesting way.
One possible reason could be a misunderstanding. Erza might misunderstand Naruto's intentions. For instance, if Naruto is on a mission that involves some secretive actions, Erza could misinterpret them as something malicious and decide to betray him.