Well, it could be that Hinata says something really cruel to Naruto by mistake. For example, she might tell him that she was only being nice to him all along because she pitied him. Naruto, who has always valued her kindness and what he thought was her love, would be devastated. His whole world view of their relationship would shatter, and his heart would break into pieces.
Another possibility is a complete character distortion in the fanfiction. The writer might decide to create a 'bad Naruto' version where he has lost all his positive traits. However, this is quite far - fetched considering the strong foundation of Naruto's character in the original series. It would be a very different and probably controversial take on the Naruto - Hinata relationship.
Naruto might become more withdrawn. He's used to being this energetic and positive person, but after having his heart broken by Hinata, he could lose that spark. He might stop going out as much, avoid his friends, and just keep to himself.
One way could be through their leadership. Naruto, with his experience and strength, and Hinata, with her kind heart and support. They could start by gathering the remaining Uzumaki clansmen. Then, they might use Naruto's influence to get resources from the other villages. Hinata could help in planning the layout of the rebuilt village, making it a place full of love and harmony, just like her own family environment.
In some fanfiction, this could happen due to a misunderstanding. Maybe Hinata is forced into a situation where she has to seem like she's betraying Naruto. For example, she could be blackmailed by an enemy who threatens the safety of the village or her family. Another possibility is that there is some sort of mind - control involved that makes her act against Naruto.
In the fanfiction, since Naruto has Kurama, he has a great source of chakra. Hinata with Nibi might also have enhanced abilities. They could team up against common enemies. Naruto's brash and bold nature combined with Hinata's calm and gentle demeanor, along with their newfound powers from Kurama and Nibi respectively, would make for an interesting dynamic. Maybe they would develop new jutsus together that utilize both Kurama and Nibi's powers.
In this fanfiction, Naruto might gain new and unexpected powers. Since the seal is broken, the Nine - Tails' chakra could be unleashed in a more uncontrolled way, leading to both challenges and opportunities for Naruto. He may have to quickly learn to master this new - found power or face being consumed by it.
Another possibility is that the writer wanted to explore different character reactions. Naruto might initially be devastated. He could go through a phase of disbelief and then anger. However, if it's a well - written fanfic, there would likely be a resolution where the truth comes out and their relationship is either repaired or redefined.
There could be a scenario where Kushina comes back to life somehow in the fanfiction. She might then play matchmaker between Naruto and Hinata, using her knowledge of Naruto to help Hinata understand him better. For example, she could share stories of Naruto's childhood that would make Hinata feel closer to him.
Perhaps in the fanfiction, there's a tournament or a competition. Naruto would be eager to prove himself, Hinata would be quietly determined, and Renamon could show off her combat skills. Their interactions during the event could lead to new friendships and rivalries. They might also learn new techniques from each other during the process.
Well, in a 'naruto absorbs hinata fanfiction', Naruto could absorb Hinata's gentle and kind-hearted nature along with her skills. This might change his personality a bit, making him more empathetic. And perhaps he could use Hinata's family techniques in a new and creative way, like combining the Gentle Fist with his Rasengan.