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.
Kakashi Sensei could also be involved. He is Naruto's teacher and mentor. If Naruto gets hurt during a mission that Kakashi is leading, Kakashi would surely be there. He might feel responsible for Naruto's injury and would do everything he can to protect him further and get him to safety. And then there's Pain. In some fanfics, Pain could be the one who attacks Naruto and causes him to get hurt, especially if the fanfic is centered around the events related to Pain's invasion.
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.
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.
Obviously, Naruto is the central character. But other characters like Sasuke could also be involved. Sasuke might be torn between his loyalty to Konoha and his friendship with Naruto. He could either try to bring Naruto back or join him in his exile.
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.
Another possible main character could be Kakashi. He has a lot of knowledge and experience. In a 'naruto time orb fanfic', he could be the one guiding Naruto or Sasuke in their use of the time orb, or he might even be tempted to use it himself to change some past events that haunt him, like the loss of his comrades.
Sasuke could be involved. He and Naruto often have intertwined stories. Sasuke might either be an ally in Naruto's destruction of Iwa, or he could be there for his own reasons, like seeking power or revenge.
Obviously Harry is one of the main characters since his name is in the title. It's also possible that there could be characters related to Ravenclaw, like Luna Lovegood who could be involved in the story about Ravenclaw money. Maybe there are also some original characters created by the fanfic author to help drive the plot forward regarding this money issue.
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.
There could be a rival within the family. Someone who wants Percy out of the way, perhaps for inheritance reasons or because they're jealous of Percy's abilities or popularity. This rival could be the one who instigates the events that lead to Percy's disownment. And then there might be a mentor - like figure outside of the family who takes Percy in after he's disowned and helps him to grow and face his new situation.