Well, he might start being more mysterious like Tobi. He could start using more deception in his actions, for example, hiding his true intentions from his friends just as Tobi often did. Maybe he'll also start using some of Tobi's speech patterns or ways of interacting with others in a more indirect and puzzling way.
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.
One way could be to give Harry a more mysterious and aloof side like Tobi. Maybe he starts using illusions or misdirection in battles at Hogwarts, similar to how Tobi uses his Sharingan abilities. He could also adopt Tobi's habit of speaking in riddles, making his classmates and teachers wonder what he's really thinking.
In a fanfiction where Naruto acts like Gintoki, his sense of humor would change drastically. Gintoki has a very specific brand of humor that includes a lot of self - deprecation and poking fun at others in a good - natured way. Naruto, who is more of an optimistic and positive - minded character, would have to adapt to this new type of humor. He might start making jokes about his own shortcomings, which is not something he usually does. His interactions with characters like Sasuke and Sakura would become really different. For example, he could tease Sasuke in a more sarcastic way rather than the usual friendly banter. This would add a whole new dynamic to their relationships.
In the 'harry potter acts like tobi fanfiction', Harry Potter's behavior could change in several ways. Tobi is known for his ability to manipulate situations to his advantage. So, Harry might start using his knowledge and skills in a more calculating way. For example, he could be more strategic in his interactions with his friends and enemies alike. Instead of being straightforward, he might play mind games like Tobi does. He could also become more solitary, as Tobi often keeps to himself, and only reveals his true intentions when it suits him. This would be a significant departure from Harry's more open and honest nature in the original series.
In a 'naruto acts like gin fanfiction', Naruto might be quieter and more observant. Instead of his usual boisterous self, he could be more like Gin, who is often sly and calculating. Maybe he would have a more subdued way of showing his power and a different approach to his enemies.
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.
One possible plot could be that Naruto starts adopting Deadpool's fourth - wall - breaking style. He might make jokes about his own story, like how he's always chasing Sasuke and how it's like an endless loop. For example, he could look at the reader and say something like 'You think I'll catch him this time? Maybe, maybe not!'.
One possible plotline could be Naruto getting some of Kaneki's ghoul - like powers. So he has to deal with the hunger for human flesh in a way that's similar to Kaneki's struggle, but in the Naruto universe. Maybe he tries to resist it while still protecting his village.
Well, it could mean that Naruto might adopt Ulquiorra's cold and detached demeanor. He might start speaking in a more monotone way, like Ulquiorra. Also, his fighting style could become more calculated and less impulsive, similar to how Ulquiorra approaches battles in a very methodical manner.