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.
Well, it's not super common but it does exist. In some fanfictions, the 'Naruto bullies Hinata' scenario is used as a starting point to show character growth. For example, Naruto might start off bullying Hinata out of immaturity or misunderstanding, and then as the story progresses, he realizes his mistake and tries to make amends. This can lead to a deeper connection between them in the end.
One popular fanfiction might be where Hinata's bullying of Naruto is a misunderstanding. Maybe she was trying to get his attention in a really wrong way because she actually had a crush on him. For example, she could be stealing his lunch as a way to start a conversation, but Naruto takes it as bullying.
Some bullies might mock or make fun of spiderman fanfic. They could see it as something only 'nerds' are into and use it as another reason to pick on fans. For example, they might laugh at the outlandish plot ideas or the 'geeky' passion of the fans.
Once upon a time, Hinata was being bullied near the training grounds. The bullies were taunting her about her shy nature. Just as they were about to get physical, Naruto showed up. He remembered all the times Hinata had been kind to him. 'You guys think it's cool to pick on someone smaller?' Naruto asked. The bullies tried to act tough but Naruto's presence was too much for them. He then turned to Hinata, 'Don't let them get to you. You're strong, Hinata.' And from that day on, Hinata felt a little braver knowing Naruto had her back.
In many Naruto fanfictions, Naruto might save Sakura from bullies by using his ninja skills. He could use his shadow clone jutsu to surround the bullies and intimidate them. Maybe he'd also give them a stern talk about kindness, as Naruto has a big heart.
One story could be about Sakura constantly making fun of Naruto's dreams in the fanfiction. For example, she might mock his aspiration to become Hokage, but Naruto, with his unwavering determination, eventually proves her wrong and she realizes her mistake. Another could involve Sakura excluding Naruto from team activities in a rather mean - spirited way, but Naruto's friends come to his defense.
At first, Naruto might be shocked and heartbroken. He has always longed for family acceptance, so being banished by them would be a huge blow. He could feel betrayed and angry, especially if he doesn't understand the reasons behind it.
At first, Naruto may be heartbroken and confused as to why he is being bullied. He might cry in private, but in public, he tries to put on a brave face. As time goes on, he realizes that he can't let the bullies control his life. So, he tries to find friends who will support him, like Shikamaru or Choji. With their help, he begins to stand up to the bullies more effectively and also works on building his own self - confidence.
He might be initially shocked and heartbroken. Naruto has always valued his friends and the village's trust, so when that's suddenly taken away, he's in disbelief. He could try to reason with his friends at first, but when they don't listen, he might become angry and determined to prove his innocence on his own.