The other ninja from the Hidden Leaf Village like Shikamaru, who is known for his intelligence, could be involved. He might be the one to piece together the puzzle of Naruto's faked death. And of course, villains or antagonists could also be part of the story. They might be the reason why Naruto has to fake his death in the first place or they could be trying to take advantage of the situation created by his 'death'.
In many fanfictions, Kakashi could be involved. As Naruto's former teacher, he has a deep connection with him. He might be the one who discovers some strange things about Naruto's 'death' and starts to look into it further. Hinata is another character that could be important. Her love for Naruto might drive her to not accept his death easily and she could play a part in uncovering the truth.
In a lot of these fanfictions, Luna Lovegood can be a key character. She has an open - minded and unique way of looking at things. So she might be the one who first suspects that Harry isn't really dead, or she could be part of the plan to help Harry fake his death and then communicate with him in some secret way while everyone else thinks he's gone.
Often, the main characters are Naruto and his friends. Naruto, as the protagonist, is naturally drawn to the mystery of the egg. His friends like Shikamaru, who is intelligent and can strategize about how to deal with the situation regarding the egg, and Choji, who might provide some physical protection if needed. Hinata could also be involved, perhaps having a special connection to the egg because of her Byakugan. And then there are the villains, like the members of the Sound Five, who might want to get their hands on the egg for their own evil purposes.
Naruto himself is almost always involved as he is the main character of the Naruto series. His friends like Sasuke and Sakura may also be part of the story. Sometimes, even villains like Orochimaru or Madara could be involved if the plot of the fanfiction is related to a big threat where their knowledge or power is needed.
Obviously, Naruto himself is the central character as it's about him 'snapping'. Sasuke is also often involved. He might be a factor in what causes Naruto to snap, or he could be on the receiving end if Naruto's snapping is directed at his actions or decisions.
In 'naruto angry fanfiction', characters like Hinata can also be involved. If she is in danger or if Naruto feels that he couldn't protect her well enough, it can stir his anger. And villains like Orochimaru or Madara can be present as they are often the source of problems that make Naruto angry, whether it's through attacking the village or harming his friends.
Princess Peach could also be a main character. In some fanfics, she could be the catalyst for Bowser's death. Maybe her capture by Bowser sets off a chain of events that ultimately leads to his end, or she could be the one who finally defeats him in a twist of the story.
Obviously Naruto is the main character as he is the one usually pulling the pranks. His friends like Shikamaru might also be involved, either as victims of the pranks or as accomplices. Sakura could be in there too, perhaps getting annoyed at Naruto's pranks or being part of a prank on someone else.
Obviously Naruto is the main character. And sometimes his parents might be involved in a more complex way, like through flashbacks or alternate storylines where they had reasons for the so - called 'abandonment'.
Obviously Naruto himself is the central character as it's about his lifeless eyes. Sakura could also be involved as she is one of Naruto's closest friends. She might be the one to notice the change in his eyes first and try to help him.
Obviously, Naruto himself is the central character. But other characters like Sakura might also be involved. She could be the one trying to get Naruto sober or scolding him for his drunken behavior.