Hinata would also play a major role. Since she has deep feelings for Naruto, she would be devastated by his amnesia. She might try to use their shared memories, like the time she confessed her love to him during the Pain attack, to jog his memory. And the Akatsuki members could also be involved in some cases. If Naruto's amnesia was caused by their actions, they might be the antagonists in the fanfiction, or they could also be trying to use his amnesia for their own purposes.
Iruka Sensei could be another important character. He was Naruto's first teacher and has a special bond with him. He would be very concerned about Naruto's amnesia and would try to remind him of their early days at the ninja academy. Also, characters like Shikamaru, who is known for his intelligence, could be involved in coming up with plans to help Naruto regain his memory.
Kakashi could also be an important character. He has a lot of experience and wisdom. When Naruto gets high, Kakashi might be the one to guide Naruto through this strange state, using his own past experiences and knowledge of different ninja techniques. And then there's Jiraiya. Given his relationship with Naruto, he would surely be involved, perhaps trying to use his own unique jutsu to help Naruto come back to normal.
Obviously Naruto himself is the main character involved. But his friends like Sasuke, Sakura, and Kakashi are also likely to be involved. Sasuke might be affected by Naruto's wishes, for example, if Naruto wishes for Sasuke to fully return to the Hidden Leaf Village and be at peace. Sakura could also be involved, perhaps in helping Naruto make his wishes come true in a medical or support way. And Kakashi, as Naruto's former teacher, would surely play a role in guiding Naruto in how to use his wishes wisely.
Obviously Naruto himself is the central character as the story is about him getting disowned. His friends like Sasuke and Sakura might also be involved. Sasuke could be conflicted between his loyalty to the village and his friendship with Naruto. Sakura might initially be confused about whether to side with the village or Naruto. And then there are the village elders like Danzo who could be the ones behind Naruto's disownment in the fanfic.
Sasuke is very likely to be involved. Given their complex relationship, Sasuke could be the one who finds Naruto severely injured and has to make a choice between helping him or leaving him. Another character could be Sakura. As a medic - ninja, she would be the one to try and heal Naruto's severe injuries. Kakashi too might be involved, either as a mentor figure who tries to figure out what happened to Naruto or as someone who has to step in to protect Naruto from further harm while he is injured.
Obviously Naruto himself is the central character as it's about his hibernation. His friends like Sasuke and Sakura are also likely to be involved. They would probably be the ones most concerned about his condition and try to figure out what happened.
Obviously, Harry Potter himself would be the central character. He's the one getting the tattoos after all.
The villains in the Harry Potter series, such as Voldemort or his Death Eaters, could also play important roles. Harry's anger might be directly related to their actions. For instance, if Voldemort were to target someone Harry cares about again, it could be the trigger for his extreme anger. His interactions with these villains in the fanfiction would be full of tension and high - stakes confrontations.
In addition to the above, other characters from the wizarding world could be involved. For example, the Order of the Phoenix members. They might be suspicious of Harry at first but then come to his aid. And there could be some new characters created specifically for the fanfiction. Maybe a mysterious old wizard who has knowledge about the Dark Mark that no one else does and helps Harry on his journey to rid himself of it or at least understand it better.
Toriel is very likely to be involved. She has a motherly nature and would surely be concerned about Frisk's health. She would probably be at Frisk's bedside, offering comfort and warm food.
Obviously, Dumbledore himself is the central figure. Then there would be characters like Harry Potter, who might have mixed feelings about Dumbledore after learning some of his secrets. Hermione Granger could also be involved, using her logical mind to analyze the situation. And perhaps members of the wizarding government, such as the Ministry of Magic officials who might be the ones to judge Dumbledore.