One way this could work is if there was a shared ancestry that was hidden or lost over time. Perhaps there was an ancient clan that had members in both the Naruto world and the Fairy Tail world. Through some convoluted plot device in the fanfic, Naruto and Erza could be discovered to be part of this long - forgotten clan, thus making them siblings.
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.
In fanfiction, the idea of Naruto being Itachi's half - brother might be based on some creative reinterpretation of the clans. Suppose there was a long - lost connection between the Uzumaki and the Uchiha clans. This could potentially lead to a situation where Naruto and Itachi share a half - brother relationship. However, it's important to note that this goes against the canon story. The beauty of fanfiction is that it allows for these kinds of 'what - if' scenarios.
Well, in fanfiction, anything can be possible. Maybe some sort of magical or divine intervention could be the reason. For example, a powerful wizard or god could have manipulated events to make them siblings across different fictional worlds. It could also be due to some sort of alternate reality where the rules of both the Harry Potter and Percy Jackson universes are blended in a unique way.
It could be a comical take in the fanfic as well. Maybe a crazy inventor or a bumbling wizard accidentally casts a spell that merges the two worlds in a strange way, making Sephiroth Naruto's brother. This would lead to hilarious situations like Sephiroth trying to understand Naruto's love for ramen or Naruto being baffled by Sephiroth's long, flowing hair and his rather dark and brooding personality.
Well, if we consider the concept of fanfiction, it might involve a lot of creative liberties. One way this could work is if there was a reality - warping event. Say a villain was messing with different universes and ended up combining aspects of Wolverine's genetics with someone in the Naruto world, and Naruto was born as a result. It's all about bending the rules to create an interesting and unique story.
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.
One possible plotline could be Naruto being transported to the Fairy Tail world and finding out he has a sister in Erza. They then team up to fight common enemies. Another could be that they discover their connection later in life and have to deal with the shock of having a long - lost sibling from another world.
Well, in the Naruto universe, for Naruto to make a Treant Jutsu, he might first need to study nature chakra deeply. He could observe how trees grow and thrive, and then try to infuse his own chakra with the essence of nature. Maybe he'd have to combine his shadow clone jutsu in a new way, having clones study different aspects of trees, like their root systems and how they absorb nutrients. Then he could use his Rasengan as a base and add the nature - based tree - like elements to it, gradually forming a Treant - like structure out of his chakra.
It's highly unlikely. In the Naruto universe, they don't really have the concept of fanfiction as we do in our world. Their focus is more on real - life ninja activities, training, and village affairs.
A plotline could involve a magical artifact that has the power to change the fabric of different universes. Naruto, Mirajane, and Erza are all drawn to it for different reasons. Naruto wants to use it to protect his village, Mirajane to protect her guild, and Erza for the sake of justice. As they fight over the artifact at first, they realize that a greater evil is trying to use it for destruction, so they join forces. Along the way, they learn about each other's worlds and cultures, and their relationships grow.