One possibility is that Naruto, with his determination, could adapt Zeref's powers in a unique way. Maybe he'd use Zeref - like magic to enhance his ninjutsu. For example, he could infuse Zeref's death - based magic into his Rasengan, creating a more powerful and dangerous attack. Another aspect could be Naruto's personality change. If he becomes influenced by Zeref, he might become more brooding and less of the cheerful ninja we know. However, his core values of friendship and protecting the village would still likely be there, just warped a bit by Zeref's dark nature.
Yes, there are likely some fanfictions out there with this concept. You can try searching on popular fanfiction websites like FanFiction.net or Archive of Our Own. Just type in 'Naruto Brother of Zeref' in their search bars and see what comes up.
In some fanfictions, Zeref is portrayed as a more sympathetic character. Instead of just being the big bad, he might be shown as a victim of his own power or circumstances. For example, he could be a character who was forced into doing evil things and actually has a good heart deep down.
One common theme is redemption. Many fanfictions explore the idea of Zeref being redeemed through his interaction with the female character. For example, the female might show him kindness or love that he has never experienced before, leading him to question his evil ways.
Well, it's quite possible. Fanfiction writers often come up with the most creative and unexpected crossovers. Since Naruto, Mavis, and Zeref are from different fictional universes, a fanfiction combining them in such a way could be a really interesting read. However, you'll have to do some searching on the various fanfiction hubs to find it. Some of these stories might be quite rare, but if you dig deep enough, you may come across one.
One common theme is power struggle. Since Zeref is a very powerful character, when he crosses over into other universes, there is often a struggle for power with the existing powerful entities in those worlds. For example, in a crossover with a superhero universe, Zeref's dark magic might clash with the superpowers of the heroes.
It's very possible. In the realm of fanfiction, all sorts of wild ideas are explored. Since both Naruto and Zeref come from different fictional settings, a fanfiction writer might have decided to blend the two. Maybe they saw some similarities in their characters' powers or personalities that led them to create a story where Naruto is Zeref's son. This could also open up a whole new set of plotlines, such as Naruto having to deal with his newfound heritage and the implications it has on his relationships in the Naruto universe.
There's a fanfiction where Lucy and Zeref meet in a parallel dimension. This dimension has its own set of rules and magic. The story could show how they adapt to this new world and how their relationship develops in this strange setting. It might have elements of romance as they rely on each other for survival. Another one could be a fanfiction that starts with Zeref being in a weakened state and Lucy finds him. She decides to help him, not knowing who he really is at first. As the story progresses, their bond grows and they face challenges together. And a third one could be a fanfiction that reimagines their story in a modern - day setting, with Lucy as a normal girl who discovers she has magic and Zeref as a mysterious figure from a forgotten past.
Typically, it might explore a different side of the characters. Maybe it shows Zeref from a female perspective, which could bring new interpretations of his powers and motives. And for Nirvana, it could add new dimensions to the story.