In fanfiction, the idea of Naruto having a son with Itachi might be part of a complex AU (alternate universe). The story could set up a world where the Uchiha and Uzumaki clans have a different relationship. Itachi, instead of following his original path, gets involved with Naruto in a way that leads to the birth of a son. This could be due to political alliances, or a new prophecy in this alternate Naruto universe that binds their fates together.
In a fanfiction context, it could be possible through some creative plot devices. Maybe a powerful jutsu was used that altered their memories or destinies. For example, a rogue ninja with a forbidden time - bending jutsu made them believe they were in love and got married. It could also be due to some sort of political alliance gone wrong in a strange way, where they were forced into a marriage - like situation and over time, developed real feelings for each other.
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 made possible. It could be that Naruto was the result of an experiment. One mother could be his biological mother who gave birth to him, and the other could be a woman who was involved in some genetic manipulation or chakra - infusion process that also made her a kind of'mother' to Naruto in a very non - traditional sense.
In this fanfiction idea, it might be that a powerful being from a higher dimension decides to mess with the fates of these two universes. They could manipulate the timelines and genetics in such a way that Naruto is born as Toriko's son. This would completely change Naruto's backstory and his relationship with the Hidden Leaf Village. He might grow up with a whole new set of values and powers influenced by Toriko's world, like having a stronger focus on food - based powers or a different view on combat.
It's not really possible within the normal Naruto lore. But fanfiction is all about exploring 'what ifs'. In a yaoi fanfiction where Naruto brings Itachi back to life, it could be based on some extreme emotional bond. Maybe Naruto discovers a hidden power within himself that he can use to reverse death. But this goes against the established rules of the Naruto world where death is usually final. So, it's really a matter of the author's creativity and how they can justify such a huge event within the framework of the Naruto world, even if it's a yaoi - inspired take on it.
If Naruto was Itachi's son in fanfiction, it would completely turn the story upside down. For one, Naruto's character arc would be different. His relationship with Sasuke would be more complex as Sasuke was Itachi's real brother. Naruto might have inherited some of Itachi's skills or traits. Also, the whole concept of Naruto being an orphan would change. Instead of being alone, he might have grown up with some knowledge of his Uchiha heritage, which could have led to a different path in his ninja training and his goals in the village.
It could be a complex plot where Naruto, disillusioned with the shinobi world for some reason, decides to create a new identity as the Masked Man. He might have seen too much corruption or pain and believes that by operating from the shadows as the Masked Man, he can bring about real change. He could be using the mask as a symbol to strike fear into those who are causing harm, while also trying to protect the ones he loves without them knowing it's actually him.
It could also be that Naruto has been influenced by Itachi's self - sacrifice. He saw how Itachi sacrificed everything for the greater good. So, in the fanfiction, Naruto might secretly work for Itachi as a way of carrying on his legacy. He may be helping Itachi from the shadows to achieve goals that Itachi was unable to complete during his lifetime.
In this kind of fanfiction, it could be developed through shared traumas. Naruto, who has his own painful past, might find a connection with Itachi's complex and tragic backstory. They could start to understand each other on a deeper level during some missions or encounters where they have to rely on one another. Naruto's optimistic nature might start to break through Itachi's cold exterior, gradually leading to feelings of love.
Well, in a really dark and twisted fanfiction, Sasuke could be under some sort of mind - control spell. The spell could be so strong that it overrides his feelings for Naruto. He might then attack and kill Naruto without fully realizing what he's doing. But in the real Naruto lore, their friendship and mutual respect are so strong that this is highly unlikely.