It is not ethical. Hinata Hyuuga is a character, and creating fanfiction that involves abuse goes against the spirit of respecting the character and can also be disturbing to other fans who love the character for her positive traits.
In a Naruto pranks Hyuuga fanfiction, Naruto might use his typical mischievous tactics. For example, he could use his shadow clone jutsu to create chaos around the Hyuuga compound. Maybe he'd make clones that pretend to be important visitors and then act all silly to embarrass the Hyuuga. It would be a really funny scenario as the serious Hyuuga clan tries to deal with Naruto's antics.
They would probably be very proud. Despite their differences, both Hinata and Neji are highly skilled members of the Hyuuga clan. For the clan, watching them fight in the fanfiction would be like seeing the best of their combat techniques and kekkei genkai on display. They might also be analyzing their moves to see how they can further improve the clan's fighting style.
Naruto could prank the Hyuuga by changing the signs on their training areas. So instead of the correct instructions for their Gentle Fist training, there are completely wrong and silly ones. This would disrupt their training sessions and lead to some really funny moments as the Hyuuga try to figure out what went wrong.
In this kind of fanfiction, Naruto might gain access to the Hyuuga's unique fighting techniques. For example, he could start learning the Gentle Fist style. This would make him an even more formidable ninja. He might also be exposed to the Hyuuga's clan politics and traditions, which could be a whole new world for him compared to his life as an orphan in the original story.
Some fans who like the Hyuuga characters might be disappointed. They might feel that Naruto's dislike in the fanfic is unfair to their favorite characters and could lead to some debates within the community.
Well, the Hyuuga clan has certain expectations and standards. Their presence during the Hinata vs Neji fight in the fanfiction would make both fighters more conscious of these. Hinata, who has always been in Neji's shadow in the eyes of some in the clan, would be trying extra hard to show that she can be a great Hyuuga. Neji, who has always been seen as a strong representative of the clan's old ways, would be fighting not just to win against Hinata but also to maintain his status among the clan. Their fight is thus shaped by the clan's overarching influence.
Naruto could develop a stronger sense of family within the Hyuuga clan. Since he is born into it, he would be more involved in clan politics and relationships. He might strive to improve the clan's standing in the village, and this would shape his character into a more responsible and clan - centered person. He would also have to deal with the internal rivalries within the Hyuuga, which could make him more politically astute.
Well, if Naruto is born a Hyuuga in the fanfiction, he would likely have the Byakugan from birth. This would change his perspective and abilities completely. He might not be the outcast he was in the original story, but instead have to live up to the high expectations of the Hyuuga clan. His relationship with Sasuke could also be affected. Since the Hyuuga are more focused on their own clan affairs, Naruto might not be as eager to pursue Sasuke when he leaves the village, or their rivalry could take on a different form because of Naruto's new clan identity.