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.
In this type of fanfiction, the antagonists could be a new group of rogue ninjas. They are inspired by Pain's ideology but take it to more extreme levels. They target Hinata to get to Naruto, knowing that Naruto cares deeply for her. Also, there could be some internal political opponents in Konoha who oppose Naruto and Hinata's relationship, fearing it could disrupt the traditional power balance in the village.
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.
One possible antagonist could be a jealous student. Maybe someone who has a crush on Hinata and doesn't like Naruto getting close to her. This student could try to sabotage their projects or spread false rumors about them at the academy.
One possible plot could be that Hinata and Naruto start to train together more intensively. After facing Pain, Naruto realizes Hinata's feelings for him more deeply. They could go on missions side by side, and Hinata becomes stronger under Naruto's influence. Naruto, in turn, starts to see Hinata as not just a friend but someone he could potentially have a future with.
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.
Well, it's possible that Hinata becomes more confident around Naruto after the Pain Invasion. She might be more forward in expressing her emotions, which could lead to Naruto reciprocating her feelings. Maybe they go on adventures together in the village, helping people out and in the process, their bond grows stronger. They could also have some really deep conversations about their pasts, their dreams, and how they see the future of the village, which further cements their relationship.
One main antagonist could be a rogue ninja from a hidden village. This ninja has a vendetta against Konoha and targets Naruto and Hinata specifically because of their importance to the village. He uses powerful dark jutsu to try and stop them in their adventures.
The main antagonists could be other powerful clans in the Hidden Leaf Village. For example, the Uchiha clan (if they were still around and had some grudges or power struggles). They might see the restoration of the Hinata clan as a threat to their own status and power within the village.
Another type of antagonist could be a strict professor who doesn't like Naruto's carefree attitude and Hinata's association with him. The professor might try to give them a hard time, like assigning them extra difficult projects or being overly critical in class, which becomes an obstacle in their college life and relationship.
It could be some rogue ninjas who are against Naruto's new peaceful policies as Hokage. They might see Hinata as a weakness to be exploited to get to Naruto.
It could symbolize a new chapter in their relationship. Before, Naruto was mostly focused on his goals and being recognized in the village. But after facing Pain, he might have a new perspective on life and love. The kiss with Hinata could be the start of a deeper, more romantic connection, showing that he's ready to explore his feelings for her and let someone be close to him in a different way.