In the Naruto world, power and respect are important. Kiba might have disrespected Naruto in front of others, or tried to undermine his authority. Naruto, having grown as a character, wouldn't tolerate such behavior and would take steps to put Kiba in his place. Another possibility is that there is some sort of competition for a rare resource or a powerful jutsu. Kiba tries to get it by underhanded means and Naruto stops him, which could be seen as 'destroying' Kiba's plans in the context of the fanfic.
It could be that Kiba has been involved in something that Naruto considers wrong. For example, if Kiba endangered the safety of the village or their friends, Naruto, being the protector - type, would take action against him. Or perhaps there was a misunderstanding between them. Kiba might have been framed for something, and Naruto, believing the false information, tries to 'destroy' Kiba in the heat of the moment.
One possible motive could be jealousy. If Kiba were to gain more recognition in the village than Naruto in the fanfiction world, Naruto's insecurities could drive him to do something drastic like killing Kiba. But this is a huge departure from his usual self.
Since I'm not familiar with this particular fanfic, I can't give a proper summary. But if we think about it, in the Naruto universe, Naruto is a very powerful character. If he is to 'destroy' Kiba in a fanfic, it might be related to their rivalry. Maybe it's about Naruto proving his superiority in a mission or a battle within the story of the fanfic. It could also be a more complex plot where Naruto's actions towards Kiba have far - reaching consequences for the whole ninja village or their group of friends.
One possible motive could be a misunderstanding. Maybe Naruto discovers some false information that makes him believe Konoha has betrayed him. For example, if he's wrongly led to think that the village elders are planning to harm his friends or his sensei. Another motive could be the influence of a powerful and evil entity that has somehow managed to control Naruto's mind. It could use Naruto's strength to achieve its own goal of destroying Konoha.
One possible reason could be a threat to Konoha. If Iwa planned an attack on Konoha, Naruto, as a defender of his village, might take the fight to them and end up destroying parts of Iwa in the process.
In some fanfics, they might be partners in a special team. Working together to uncover secrets in the ninja world or to take on a powerful and dangerous enemy that no one else can defeat.
Perhaps Naruto has a newfound confidence or a change in his personality that makes Kiba and Issei twitchy. In the fanfic, if Naruto starts acting more recklessly or assertively than usual, it might make them nervous. It could also be that Naruto has some sort of connection to an enemy or a dark force that Kiba and Issei sense, and that's what is making them twitchy.
One possible plot could be that Naruto, in the heat of a battle, somehow acquires Kiba's blades. He then has to quickly learn how to use them effectively against an enemy. Maybe he combines his own chakra - based attacks with the physical power of the blades.
Another great one is 'Naruto and Kiba: The Unlikely Alliance'. In this fanfiction, they are forced to work together in a difficult situation that neither expected. It shows their different skills and how they combine them to overcome challenges, and in the process, their friendship deepens.
Maybe the plot could revolve around a competition in the village. Female Naruto and Kiba both enter, and at first they are rivals. But as the competition progresses, they realize they have more in common than they thought. They could end up teaming up against a more powerful opponent within the competition, and this experience could bring them closer together romantically.
One possible plotline could be that they are in a village or a world where there is a sudden increase in the use of explosive jutsus or weapons. Naruto, Kiba and Issei have to face their fear as they are constantly under the threat of these explosions. Maybe they start off by trying to avoid areas where explosions are likely to occur. For example, they might stay away from battlefields or places where ninja experiments with explosive substances are taking place. As the story progresses, they could be forced into situations where they have to confront their fear directly, like when their friends or loved ones are in danger in an explosion - ridden area. This would be a great opportunity for character development as they learn to overcome their fear for the sake of others.