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.
If Harry Potter started acting like Tobi Uchiha, it would change his relationships completely. His friends would be confused and probably a bit hurt. Hermione, being the logical one, would try to figure out what was wrong with him. Ron might feel betrayed. In battles, Harry could use tactics similar to Tobi. Instead of straightforward dueling, he might use distractions and illusions, which would be a new and unexpected approach in the wizarding world, throwing his opponents off guard.
The main characters are obviously Tobi and Deidara. Tobi is known for his somewhat comical and mysterious behavior. Deidara is an artist who uses his explosive art as a weapon. In the fanfiction, they are often the central focus of the story.
Well, if we go by the name, the main character is Tobi for sure. And as for the other part of the love story, it could be any of the Akatsuki members. It could be Konan, who has her own charm and powers. Or it could be someone like Kisame, though that would be a really strange pairing. But in fan - made stories, the possibilities are endless when it comes to pairing Tobi with an Akatsuki member.
Definitely Kakashi. Since he has a connection to both Naruto and Tobi (Obito), his presence can add a lot of depth. He can be the one who tries to bridge the gap between Naruto and Tobi, or he could be a source of conflict as he has his own history with Tobi.
It could be Sasuke's sister, if there was one in the fanfiction world. She might share some of Sasuke's traits but also have her own unique personality that attracts Naruto.
Often, Naruto might be paired with Madara in some sense. Their opposing views on power and peace could create interesting interactions in the fanfiction.
Gray is another candidate. Gray's cool and collected demeanor could contrast with Tobi's more mysterious nature. They could get into arguments about the best way to handle a situation, like when facing a powerful enemy. Or, they could find common ground in their skills and work together to protect Fairy Tail from danger.
The main characters are clearly Tobi and Sakura. Tobi is the one doing the tying up, which implies he has some sort of agency in the story. Sakura, on the other hand, is the victim of this action, and she will likely be the one trying to either resist or escape from this situation.