In fanfiction, the evidence often lies in the way the author portrays Naruto's interactions. For example, Naruto may be shown being cold or dismissive towards Sakura, like avoiding her company or not showing any romantic interest. Meanwhile, with Hinata, he could be depicted as being more affectionate, like blushing around her or always coming to her aid. But it's important to note that this is all in the realm of fan - created interpretations and not the official canon.
One common plotline is Naruto realizing Hinata's worth after some event. For example, Hinata might save Naruto from a dangerous situation, and that makes Naruto see her in a new light and start to develop stronger feelings. At the same time, he could start to distance himself from Sakura because of her continued focus on Sasuke. Another plotline could be Hinata and Naruto getting paired up for a mission, during which they bond more closely while Naruto realizes how different she is from Sakura in terms of her loyalty and selflessness.
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.
One common plot device is the love triangle. It creates drama as Sakura may be jealous of Hinata's relationship with Naruto. Another is the redemption arc for Naruto's feelings. Maybe he used to be confused about his feelings for Sakura but then realizes his true love is Hinata. And there could be a friendship break - up plot device where Naruto distances himself from Sakura due to his newfound love for Hinata.
For Naruto, his character arc could start with his intense hatred for Sakura. As the fanfiction progresses, he might start to question his feelings. Maybe he realizes that his hatred was misdirected or based on false assumptions. For Sakura, her arc could be about persevering in her love despite Naruto's hatred. She could grow stronger and more confident in expressing her feelings and trying to change Naruto's view of her.
Some fans might be divided. Those who like Hinata might support the idea in the fanfiction if they feel it gives Hinata more depth or a more interesting storyline. On the other hand, fans of Sakura might be offended.
In fanfiction, Naruto loving Hinata and Sakura can lead to complex relationship dynamics. Hinata's quiet love for Naruto is well - known in the original series. If Naruto also loves her in fanfiction, it could be a very sweet and gentle relationship, full of mutual understanding and support. For Sakura, Naruto's love could create a love triangle situation. It might add a lot of drama and emotional conflict, as Sakura has her own feelings for Sasuke in the original story.
A common storyline could be a love triangle where Naruto is torn between Hinata and Sakura. He has deep feelings for both, and they both have different qualities that attract him. Another one might be where Naruto first starts to develop feelings for Hinata while still having a lingering affection for Sakura from their childhood days. This can create a lot of internal conflict for Naruto.
Well, one possible plot development could be that Naruto's hatred for Sakura creates a lot of tension in the story. Maybe it leads to some kind of rivalry where they constantly compete in missions or training. And Sakura's love could be unrequited at first, causing her to strive harder to prove herself to Naruto. Another development could be that the fanfiction explores the reasons behind Naruto's hatred, like some past misunderstandings that need to be resolved for them to have a normal relationship.
Some people create such fanfiction maybe because they like to explore alternative or dark storylines. They might think it's interesting to deviate from the canon relationship between Naruto and Hinata.