Hinata might be shocked at first. She has always adored Naruto, and this sudden act of aggression from him would leave her stunned and unable to process it immediately.
Well, it could be that Naruto made a really stupid mistake that hurt Hinata's feelings deeply. Maybe he accidentally said something really mean about her family or her skills in front of everyone. So in a fit of anger, Hinata slaps him to show her extreme disappointment.
One possible reason could be a huge misunderstanding. Maybe he thought Hinata did something really bad to his friends, like unknowingly leading the enemy to them. Without knowing the truth, his hot - headed nature made him lash out.
One possible reason could be that Naruto made a comment that was disrespectful to Hinata's family or her ninja skills. For example, if he said something like her clan's techniques were weak in a thoughtless moment.
I'm not sure about specific 'hinata slaps naruto' fanfiction. You could try searching on popular fanfiction websites like FanFiction.net or Archive of Our Own. They have a vast collection of Naruto - related fanfictions and you might be able to find something that fits this rather unusual scenario there.
At first, Naruto would be shocked. He might be angry at Hinata for slapping him. But then he would start to think about why she did it. If he realizes his mistake, he could become more cautious around her. Hinata, on the other hand, would probably feel a bit guilty for slapping him, but also relieved that she got her feelings out.
It could also be related to a prophecy or a pre - determined fate in the fanfic's plot. There might be some kind of dark prophecy that says Kawaki has to kill Naruto to prevent a greater evil. Or perhaps Kawaki is being controlled by an external force that has a vendetta against Naruto and uses Kawaki as a tool to carry out the murder.
One common theme is friendship. Writers often explore how Himawari and Kawaki, who come from different backgrounds, form a bond of friendship. Another theme is growth. They both grow as characters, learning from each other.