Often, Kakashi could be part of the story too. He might be in a position where he has to deal with Naruto's drunk antics. He could be amused, or he could be concerned about how this new habit will affect Naruto's ninja training and development.
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.
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.
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.
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.
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.
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 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 a main character. Since it's about his inner hollow, he is at the center of it. Sakura might also be involved as she is one of Naruto's closest friends. She could be the one to notice the changes in Naruto due to the inner hollow and try to help him.
Obviously Naruto himself is the central character as the story is about him cutting himself. Sakura is often involved as well. She is Naruto's friend and a medical ninja. So she might be the one to discover Naruto's self - harm and try to heal him both physically and mentally.
Obviously, Naruto is the central character as it's about the Kyuubi being released from him. Sasuke also often plays a crucial role. He might be concerned about Naruto's new state, or he could be one of the characters trying to either help or stop Naruto depending on the plot.
Obviously, Naruto is the central character as the title 'naruto goes mad' implies. Sasuke often plays a crucial role too. He might be the cause of Naruto's madness in some cases, like if he betrays Naruto again in a more extreme way. Sakura could also be involved, perhaps trying to bring Naruto back from his madness. And Kakashi, as Naruto's former teacher, may try to figure out what's wrong with Naruto and find a way to help him.