The story could end with Naruto realizing his hatred was misdirected. After some big event or revelation, he discovers that his brother and sister actually care for him deeply. They all reconcile and become a closer - knit family.
Perhaps they have wronged Naruto in some way in the fanfiction. They could have betrayed him, like telling his secrets to others or getting him into trouble on purpose. This would lead to Naruto developing hatred towards them.
One possible reason could be jealousy. Maybe his brother has some special abilities or gets more attention that Naruto feels he should have. For example, if his brother is really good at a certain jutsu and is always praised for it while Naruto struggles, that could lead to resentment.
Communication is key. Naruto and his sister could sit down and have an honest conversation about what's bothering him. They could clear up any misunderstandings that led to his hatred.
One possible reason could be jealousy. Maybe the sister is more favored by the villagers or has some special abilities that Naruto feels overshadow his own. This could lead to a sense of envy and ultimately hatred.
On the other hand, this hatred could also fuel his growth in a different way. He might train harder to prove that he is better than his brother, or to get revenge. This could lead to a more powerful and perhaps more complex Naruto, as he battles with his inner emotions while also striving for power and recognition.
One common plot could be that the sister has a different ideology. For instance, she might believe in a more radical approach to achieving peace in the ninja world compared to Naruto's more inclusive and forgiving way. This difference could lead to clashes and eventually Naruto's hatred. Another plot could be a power struggle. If the sister is extremely powerful and uses her power in a way Naruto doesn't approve of, like being cruel to weaker ninjas, it could make Naruto hate her.
It could also be that Naruto has been influenced by some external force in the fanfiction. For instance, an enemy might have planted false memories or ideas in his head, making him believe that his parents and sister are bad. This false perception could then fuel his hatred.
In the original Naruto story, Naruto is mostly alone and doesn't have a twin sister at all. So this fanfiction completely adds a new character dynamic that doesn't exist in the original.