Hinata could also be a common character. She may try to help Naruto secretly, or be heartbroken by his banishment and strive to change the village's decision. Another character could be Kakashi. He might be one of the few who believe in Naruto's innocence and try to find a way to bring him back to the village.
Sasuke is often a common character. He might have a different reaction to Naruto's banishment compared to the original story. Maybe he decides to join Naruto outside of Konoha or tries to find a way to get him back. Kakashi could also be there. He might be conflicted about Naruto's banishment and could play a role in either helping Naruto secretly or trying to uphold Konoha's decision.
Jiraiya is another character that could be present. As Naruto's mentor, he would be concerned about Naruto getting the cursed seal. He might try to find a way to remove it or at least teach Naruto how to manage it without losing himself. Jiraiya's vast knowledge of ninja arts could play a crucial role in Naruto's struggle with the cursed seal.
The council members themselves would be key characters. They are the ones making the decision to banish Naruto. Also, characters like Iruka sensei could play an important role. He might be torn between his loyalty to the village and his belief in Naruto. Another could be Sasuke. He might react in different ways, either trying to help Naruto or seeing it as an opportunity to prove his own superiority.
Definitely Naruto is the central figure. In the harem, Hinata is a very likely character since she has always been in love with Naruto. Sakura might also be there as she has been one of Naruto's closest friends. Tenten could be another addition. She has interacted with Naruto in the series and could potentially be part of the harem in this fanfiction. Also, Temari, who has had some interesting encounters with Naruto, might be a character in the harem as well.
Sasuke would likely be involved. He has his own issues with Konoha and might side with Naruto, either out of friendship or his own vendetta against the village. Also, the elders of Konoha like Danzo could be important characters as they might be the ones behind Naruto's banishment.
Sasuke could definitely be one. He might be conflicted about Naruto's banishment, either thinking Naruto deserved it at first and then changing his mind, or trying to find a way to bring Naruto back. Kakashi could also be in it. He might be one of the few in the village who believe in Naruto's innocence and try to secretly help him.
He could marry Hinata. Even though he's banished, Hinata might follow him because of her deep love for him. Their relationship could develop further outside the village, and they could get married and start a family.
Maybe a group of outcasts similar to Naruto. They could form a team with Naruto and they all have their own unique abilities. For instance, one might be able to control the elements in a very different way than the normal shinobi in Konoha. They work together to survive in the banished land.
Jiraiya is often a common character. Since he was Naruto's teacher and had knowledge of sage training himself, he might appear in the fanfiction to guide Naruto further. Another one could be Kakashi. He is always looking out for Naruto and could be involved in the training in some way, like providing strategic advice.
Sasuke could be a common character. He might be in a situation where he has to choose between helping Naruto or following the village's orders when Naruto is on the run.