He might meet Sasuke. In some fanfictions, Sasuke, after hearing about Naruto's victory over Pain, is filled with mixed emotions. He starts to re - evaluate his own path and may decide to return to the village, leading to an emotional reunion between him and Naruto.
In some fanfictions, after Naruto defeated Pain, the village started to rebuild immediately. Naruto became a hero not only in name but also in the hearts of every villager. People looked at him with newfound respect and admiration.
He could meet Hinata, and their relationship might develop further. Maybe she would be the first to greet him and express her admiration more openly.
He might meet his sensei, Jiraiya. They could have long talks about Naruto's growth as a ninja and Jiraiya could give him more wisdom from the afterlife perspective.
The Akatsuki remnants could still pose a threat. Members like Sasori or Deidara might have had backup plans or followers who now want revenge for the Akatsuki's downfall. They could target Naruto specifically, seeing him as the one who brought down Pain and disrupted their plans.
Maybe Orochimaru's former followers who are still lurking in the shadows. They see Naruto as a threat and Hinata as an easy target to get to Naruto. Another possibility could be some power - hungry shinobi from other villages who view Konoha as weak after the Pain incident. They might target Naruto and Hinata as key figures in Konoha's future to try and undermine the village's rebuilding efforts.
He could meet an old enemy who has also changed after the war. This enemy might now be in a similar situation of being alone and they could form an unexpected bond as they understand each other's isolation.
Naruto could encounter wandering ninjas who have their own stories and reasons for not being part of a village. Some might be outcasts due to their beliefs or powers, and Naruto's interaction with them could lead to either conflict or new friendships. He may also come across some of the shinobi who fought on the opposite side during the war but now have different outlooks on life. Through these meetings, Naruto gets a broader perspective on the ninja world.
Danzo could be a main antagonist. He's always been power - hungry and has seen Naruto as a threat to his control over the village. After Pain's attack, he seizes the opportunity to turn the villagers against Naruto.
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.
Often, Naruto's relationships with other characters are explored further. He might have deeper conversations with Sasuke, trying to convince him to come back to the village for good. His bond with Sakura could also develop in different ways, perhaps becoming a stronger friendship or even something more romantic in some fanfictions.