Well, perhaps Hinata is jealous. She might see Sakura getting trained by Kurenai as an advantage that Sakura will gain over her. In the world of fanfic, there could be unspoken rivalries or insecurities. Maybe Hinata had hoped to be trained by Kurenai herself and feels left out now.
In fanfic, there could be a backstory. Maybe Hinata has some history with Kurenai that makes her sensitive to Kurenai's actions towards others. And when Kurenai starts training Sakura, it triggers those negative feelings in Hinata. It could be that in the past, Kurenai made a promise to Hinata or Hinata's family about something related to training, and now by training Sakura, Kurenai seems to be breaking that unspoken agreement.
One consequence could be a strain in their relationship. Hinata might start avoiding Kurenai, which could create an awkward atmosphere. For example, if they are in the same team or group, it could affect their teamwork.
A hinata and sakura lemon fanfic might explore the relationship between Hinata and Sakura in a unique way. It could be about their friendship growing in a lemon - scented orchard perhaps. Maybe they discover a new type of lemon together and that experience bonds them more deeply.
One possible reason could be for the sake of creating a more complex love triangle in fanfiction. Maybe the writer wants to explore a different dynamic where Naruto and Hinata's relationship is strengthened by having a common dislike for Sakura. It could also be that the fanfiction writer is trying to give Hinata more agency and make her a stronger character by having her oppose Sakura in some way, perhaps in matters related to Naruto's affections.
Some people might write them out of jealousy. For example, if they prefer other characters and feel that Naruto, Hinata, or Sakura get too much attention in the original series, they might write bashing fanfics. It's a rather immature way to deal with their feelings though.
Maybe in the fanfic, Kurenai has some actions that conflict with Naruto's beliefs. For example, she might oppose Naruto's way of handling certain village matters.
Perhaps in the fanfic, a mysterious lemon appears in their town. It has strange markings and an unusual scent. Hinata and Sakura are intrigued and decide to investigate. As they dig deeper, they find out that the lemon has a connection to an ancient legend. This discovery takes them on a journey full of mystery and adventure, and throughout this journey, their friendship is put to the test and strengthened.
One common theme is friendship. Hinata and Sakura are both strong female characters in Naruto, and many fanfics explore how they become friends and support each other. Another theme could be their growth as characters. They both have their own insecurities and challenges, and fanfics often show them overcoming these.
There may be fanfics about Sakura and Hinata in a Futa scenario. However, finding them might take some time. Start by using specific search terms on fanfic platforms. Also, keep in mind that different platforms have different rules regarding the content of fanfics, so make sure you are following their guidelines while searching.
One idea could be a story where Naruto, Sakura, Ino and Hinata go on a mission together. They face a powerful enemy and have to combine their skills. Naruto uses his shadow clones, Sakura her medical ninjutsu and brute strength, Ino her mind - transfer jutsu, and Hinata her gentle fist technique. Through the mission, they grow closer as friends and learn more about each other's strengths and weaknesses.
One great 'Naruto Hinata Sakura' fanfic is 'The Bonds of Team 7'. It delves into the deep friendships and rivalries among the characters. It shows how Hinata's quiet strength and Sakura's determination play important roles in their adventures with Naruto. Another interesting one is 'Hinata and Sakura's Training Days'. This fanfic focuses on their growth as kunoichis, with detailed descriptions of their training regimens and how they support each other in becoming stronger. There's also 'A New Chapter for Naruto, Hinata and Sakura' which takes place after the main story and shows how their relationships evolve in a more peaceful Konoha.