Sasuke is likely to be a key figure. Whether he returns to the village or continues to be an antagonist, his actions will have a big impact. Kakashi, as Naruto's mentor, could be involved in training Naruto further and guiding him in his new role as a hero. And Tsunade, as the Hokage, will still have a role in leading Konoha and working with Naruto.
Naruto himself is obviously a central character. His growth and decisions will shape the story. Hinata could also be important as her relationship with Naruto might develop further. Shikamaru, being one of Naruto's smartest friends, could play a crucial role in planning for Konoha's future and strategizing against potential threats.
Sakura could play an important role. She might be more concerned about Naruto's well - being after such a tough fight. She could also use her medical skills to help in the rebuilding of Konoha. Kakashi, too, could be significant. He could guide Naruto in understanding his new powers better and also contribute to the village's security plans.
Obviously Naruto himself is the central character. His growth and new abilities would be the focus. Sasuke could also be important. He might have his own development and his relationship with Naruto could be explored further, whether they are friends or rivals again.
Obviously, his brothers are very important. Donatello would be crucial as he could try to diagnose Leo's illness. Raph would be there to provide protection and strength if any threats come while Leo is vulnerable. Mikey would be the emotional support, trying to keep Leo's spirits up.
Hermione would definitely be an important character. She's smart and resourceful, so she'd be the one researching ways to restore Harry's memory. Ron would also be crucial as he's Harry's loyal friend. He'd be there to support Harry and keep him out of trouble. Dumbledore or other wise Hogwarts professors like McGonagall could also play significant roles. Dumbledore might have some secret knowledge or plan to help Harry, and McGonagall could provide guidance and protection at Hogwarts.
In a 'naruto after pain fanfic', Naruto is key. However, characters like Tsunade are important too. She can lead the medical and administrative aspects of the village's recovery. Then there are Naruto's friends like Kiba and Choji. They can help with the physical tasks of rebuilding, and also in the security patrols around the village to prevent any new threats.
Definitely Itachi. He has a complex character and his own sense of justice. He might see Naruto as a key to changing the shinobi world in a different way than what the Akatsuki originally planned. Another one could be Kisame. He is loyal to Itachi and would likely follow Itachi's lead in taking care of Naruto.
Harry Potter himself, of course. He has always been at the center of things in the wizarding world. His actions and decisions would likely have a great impact on any change that occurs.
Obviously, Peter Parker himself is a key character. His naivete and enthusiasm for heroism would be a big part of the story. Then there's Captain America from the Rogue Avengers. He would likely be the moral compass of the group. And Black Widow, with her skills in espionage and combat, could also be important in strategizing against any threats they face.
Sasuke is very likely to have an important role. Since he and Naruto have a long - standing relationship, Sasuke's reaction to Naruto's Six Paths powers would be significant. He might be jealous at first but then come to accept and work with Naruto in a new way.
Well, Naruto is the key figure in these fanfictions. But characters like Tsunade can't be ignored. As the Hokage, she may give Naruto special tasks or resources that aid in his rise. Rock Lee is also common. His dedication to training and his unique fighting style can inspire Naruto. And Neji, before his death in the original series, could be a character who, in fanfiction, has a change of heart and helps Naruto understand more about the Hyuga clan's secrets, which in turn helps Naruto gain more power and influence.