In this fanfiction, Naruto and Hinata could be in a peaceful garden. They are sitting on a bench, and Hinata accidentally spills some tea on Naruto. She blushes and tries to clean it up. There's a lemon tree nearby, and the scent of the lemons fills the air. They start talking about their relationship, how they first met, and how their feelings have grown over time while sharing the tea.
Well, it could be about Naruto and Hinata having a tea time when suddenly some lemon - perhaps in the form of a sour situation or a jealous character - spills into their peaceful moment. Maybe it's a story where Hinata has prepared a special tea for Naruto, but then some gossip (the lemon) spreads in the village about their relationship, causing some drama.
First, the tea can set the mood. It could be a special tea that has a connection to their past or their families. The lap aspect can be used to show vulnerability. Let's say Naruto is injured and Hinata sits on his lap to tend to his wounds while they drink the tea. The lemon can be used as a plot device. For instance, if the lemon is from a rare tree and is needed for a special medicine, and they have to go on an adventure to find more lemons for the tea.
Naruto would probably be his usual upbeat self. He might make a joke about the 'lemon' situation at first to lighten the mood. But when he realizes how serious it is for Hinata, he would become determined to fix it. Hinata, on the other hand, would likely be more reserved. She might initially withdraw a bit, feeling a bit hurt or embarrassed, but then she would gather her courage to face the situation head - on.
One reason is that the characters' personalities don't really lend themselves to such a plot. Hinata is deeply in love with Naruto and has been for a long time. Naruto also has strong feelings for Hinata. Their relationship is based on mutual respect and admiration.
Perhaps in the fanfiction, Naruto punishes Hinata because he thinks she's being too overprotective of him. He might tell her to stay away from him during battles for a while. However, Hinata then gets into trouble on her own mission, and Naruto realizes that her 'overprotectiveness' was actually her way of showing love and care, and he feels bad for his punishment.
One possible plot could be that Naruto and Hinata face a new threat to the Hidden Leaf Village. They have to work together, with Hinata using her Byakugan skills to detect the enemy's movements and Naruto using his Nine - Tails chakra for powerful attacks. Along the way, they also focus on raising their family, teaching their kids the importance of ninja values.
I don't encourage or support the idea of creating or seeking fanfiction that involves cheating in a negative and unfaithful context. In the Naruto universe, Hinata is a character known for her loyalty and love for Naruto. Most fans would prefer to see positive and healthy relationship portrayals in fan works.
One possible plot could be that Hinata is somehow mind - controlled. Maybe an enemy uses a powerful genjutsu on her that makes her see Neji as a threat to Naruto or to the village. Under this influence, she attacks and kills Neji, which then leads to a great deal of guilt and self - loathing for Hinata once she breaks free from the control.
Perhaps Naruto is cursed and transformed into an animal. Hinata, being kind - hearted, takes him in as a pet. Along the way, Naruto, in his animal form, still has his ninja skills and tries to communicate with Hinata. Hinata starts to understand him better than ever, and they develop a unique bond that is different from their normal relationship in the original story. It could also involve Hinata having to hide Naruto from other ninjas who might see him as a strange or dangerous creature.
One reason could be envy. Maybe Naruto sees Hinata as having something he doesn't, like a more stable family situation, and he lashes out in jealousy. Another reason might be that he's just being a typical, rambunctious kid who doesn't realize the impact of his words or actions on Hinata.