It could be that the author wants to explore how Naruto would be if he had some of Menma's qualities. Menma is often seen as more of a rebel or a free spirit. So, if Naruto acts like him, it might show a different side of Naruto's personality. For example, Naruto is usually very determined to become Hokage in the original story. But if he acts like Menma, he might question that goal more or take a more unconventional path to achieve it. It also adds an element of novelty and can attract readers who are looking for something new in the Naruto fanfiction world.
Maybe for a new plot twist. It makes the story different from the original Naruto storyline.
In fanfiction, the author has the freedom to experiment. Naruto acting like Menma could be a way to create new relationships and interactions. Menma has his own set of friends and enemies in his story. By having Naruto act like him, new alliances or rivalries could be formed. It could also be a way to bring in elements from Menma's story into Naruto's world, like different jutsu or cultural aspects. This cross - over of characteristics can make for a really interesting and engaging fanfiction.
One reason could be a genetic quirk or some sort of chakra - related phenomenon. Maybe there was a hidden seal or something that was activated, causing Naruto to inherit not just Minato's looks but also his mannerisms. Another possibility is some kind of reincarnation or spiritual connection.
One reason could be for strategic purposes. Itachi was a highly strategic ninja. So, in fanfiction, Naruto might act like him to outwit a particularly difficult enemy. For instance, when facing an enemy who is a master of deception, Naruto could adopt Itachi's calm and calculating demeanor to see through the enemy's tricks.
Maybe Naruto is put in a situation where he feels that Hiruzen's way of handling things is the best option. For instance, if there is a major crisis in the village that requires a more traditional and experienced approach, Naruto might choose to act like Hiruzen. Also, he could be influenced by the stories he has heard about Hiruzen and wants to fill his shoes in a way.
Maybe Naruto admires Kakashi's skills. Kakashi is a highly respected ninja, and Naruto might want to be as good as him. So he starts acting like him to learn from him.
Maybe he's on a secret mission. He could be trying to infiltrate an enemy group that Tobi was associated with. By acting like Tobi, he hopes to gain their trust and gather information.
In these fanfictions, Naruto's character is often based on his canonical self, which is full of energy and a bit of a goofball at times. Menma, on the other hand, may be a bit more mysterious or have a different backstory that shapes his character. But they can both have a strong sense of justice. Naruto has always fought for what he believes is right in the main series, and Menma can be written to have a similar moral compass in fanfiction. They may also both experience growth throughout the story, learning from their mistakes and becoming better ninja.
Another reason might be related to his pursuit of power. If in the fanfiction, Naruto is constantly facing stronger enemies and he believes that his current strength is insufficient to protect those he loves, he might attempt to sacrifice himself in a desperate attempt to gain more power, like through some dangerous and forbidden jutsu.
In the context of art, such as in performance art or avant - garde theater, forcing adults to act like babies can be a way to break social norms and shock the audience. It challenges the viewers' perception of what is normal behavior for adults and makes them think more deeply about society and human nature. This form of art often aims to evoke strong reactions and start important conversations.
It could also be a form of punishment or revenge in the story. A villain might use mind control to make a male character act like a girl as a way to humiliate him. The victim then has to go through the ordeal of acting in a way that is not in line with his own identity, and this can create a lot of drama and tension in the story as he tries to break free from the mind control and regain his dignity.
Well, in this fanfiction, it could be that Harry Potter has come across some sort of ancient magic or artifact that has changed him. Maybe this magic has a connection to Tobi's essence or the type of power that Tobi wields. Additionally, he might be trying to protect his friends in a different way. Tobi has his own way of safeguarding what he holds dear, which might seem appealing to Harry in a difficult situation. Or, there could be a prophecy or a hidden message that he has misinterpreted, leading him to believe that acting like Tobi is the right path to take.