One idea for the plot is that Naruto discovers that the person is homesick. He then uses a lemon as a symbol of home. He could say that lemons are common in their village and that they represent the familiar and comforting things. He might then plan a small 'home - like' event with the lemon as the centerpiece, like making lemon - based snacks that are popular in their village to cheer the person up.
Well, in such a fanfic, Naruto might use his positive attitude. For example, he could share some of his ninja training stories that are full of funny mishaps. The 'lemon' could be a lemonade stand that he sets up to cheer the person. Maybe he tells the person how he once made a huge mess trying to make lemonade for his friends but still had a great time.
One possible scenario could be after Naruto loses a difficult battle. Hinata might find him sitting alone, looking dejected. She could sit beside him and start by saying how she saw his amazing efforts during the fight. Then she might share some of her own insecurities and how Naruto's determination has always inspired her. This would remind Naruto of his own importance and boost his spirits.
There are also fanfics where Naruto cheers up a young genin who is feeling down because they failed a mission. Naruto shares his own experiences of failure and how he learned from them. He encourages the young ninja to keep trying and not give up, showing that setbacks are just part of the journey to becoming a great ninja.
One possible plot could be that Naruto discovers that the fox spirit inside him has a unique relationship with a lemon - based magic or energy in the world of the fanfic. Maybe there are certain quests or battles he has to face where this lemon - fox connection gives him an edge. It could also involve Naruto having to protect a lemon grove that has some sort of special significance to the fox spirit, and in the process, he learns more about his own powers and the nature of the fox within him. There could be other characters who are either intrigued or threatened by this strange combination, adding more drama to the story.
Well, one possibility could be that Naruto is exposed to some extremely powerful and corrupting jutsu that slowly drives him insane. Maybe he starts seeing hallucinations of his friends turning against him and that messes with his mind big time.
This is a rather dark and unethical concept for a fanfic. Naruto is a character associated with values like friendship and freedom. However, if such a fanfic were to exist, perhaps it could involve some sort of dark magic or curse that forces Naruto into a situation where he has to deal with slaves. But this goes against the original spirit of the Naruto series.
Hinata's shy yet determined nature makes her effective. Her love for Naruto is pure and deep. In fanfics, when she tries to cheer him up, he can sense her genuineness. For example, she might blush while telling him how great he is, which shows her vulnerability and makes her words more impactful.
One possible scenario could be that Sakura is feeling down because she failed a difficult medical ninjutsu exam. Naruto, being the good friend he is, takes her out for her favorite ramen and tells her stories of his own numerous failures and how he never gave up. This cheers her up as she realizes that failure is just a stepping stone to success.
A possible plot is that Naruto discovers a strange lemon - shaped artifact. Anko and Kurenai, being more experienced, help him figure out what it is. It turns out to be a key to an ancient ninja treasure. But they have to face various challenges and enemies who also want the treasure.
Maybe in the fanfic, Anko is teaching Naruto a new jutsu and they use lemons as part of the training. For example, they might have to hit the lemons with precise chakra control to pass a certain level of the training. Along the way, they develop a deeper bond as teacher and student, and this new jutsu becomes useful in a future battle against a common enemy.