In some cases, Naruto could be deeply hurt and withdraw from Hinata. He might question their relationship and whether he misjudged her all along. If the hurt is physical, he may also be more cautious around her in future interactions. For example, if she accidentally used a strong jutsu on him during training, he might be hesitant to train with her again without proper precautions.
Naruto might get hurt during a mission with Kaka - naru. Kaka - naru could then carry Naruto back to safety and tend to his wounds. This simple act of care can strengthen their bond.
Kakashi Sensei could also be involved. He is Naruto's teacher and mentor. If Naruto gets hurt during a mission that Kakashi is leading, Kakashi would surely be there. He might feel responsible for Naruto's injury and would do everything he can to protect him further and get him to safety. And then there's Pain. In some fanfics, Pain could be the one who attacks Naruto and causes him to get hurt, especially if the fanfic is centered around the events related to Pain's invasion.
A common plotline is Naruto getting hurt during a mission. Sasuke then blames himself if he wasn't there to protect Naruto. He might vow to become stronger so that he can always be by Naruto's side in future missions. Another is when Naruto is hurt by an enemy who specifically targets him because of his status as a Jinchuriki. Sasuke will then go on a revenge spree to take down the enemy.
Their relationship could deepen quickly. Naruto getting hurt for Hinata makes her realize just how much he cares for her. She might become more open and affectionate towards him, and Naruto, seeing her concern for him while he's injured, might also start to see her in a new light, as more than just a friend.
In the context of fanfiction, Hinata getting addicted could also be due to the creativity of the writers. They might come up with really interesting plotlines that involve Hinata more deeply in Naruto's world. The fanfiction could give her more agency or show her in situations that she wasn't in the original anime or manga, and this newness and depth make her addicted to reading these stories.
When Naruto is badly hurt, it might lead to a shift in power dynamics in the village. Some characters who were previously in the background might come to the forefront to fill Naruto's shoes temporarily. This could create new alliances and rivalries within the village, which would drive the plot forward in interesting ways.
One reason could be a powerful new enemy. Maybe an enemy with a unique jutsu that catches Naruto off - guard. The consequence would be that his friends would be extremely worried. They would probably rush to his side to protect him and find a way to heal him. His enemies might also take advantage of his weakened state to launch more attacks on the village.
He might be shocked at first. Naruto is used to seeing Kurenai as an ally, so being hurt by her would be unexpected. He could immediately ask her why she did it. If it was a serious injury, he might struggle to stay conscious while trying to understand the situation.
Simon might be in a bit of a panic. Since he's her friend and also not as used to the dangerous situations as the other Shadowhunters. He'd try to do whatever he can to help, like getting help from more experienced Shadowhunters or trying to comfort Clary while she's in pain.