Hinata could be a likely candidate in such a fanfiction. Since she is Naruto's real - life wife in the original series. Writers might twist their relationship in fanfiction and create a scenario where she betrays him. Maybe due to some family pressure or a misunderstanding that gets out of hand.
Perhaps his wife betrays him out of jealousy. She could be jealous of Naruto's status and the attention he gets. So she leaks some of his secret plans to the enemy. As a result, Naruto's missions start to fail and he becomes a target. He then has to face not only the external threats but also the heartbreak of his wife's betrayal. He might start to question his own judgment in choosing her as his partner.
It could be due to a power imbalance. If Naruto's power as Hokage makes her feel overshadowed or unimportant, she might be led to betray him. Also, perhaps she discovers some long - hidden secret about Naruto that she can't forgive, like a connection to a past enemy or some dark side of his shinobi past that he has kept from her.
He could initially go into denial. Naruto has always been an optimist. He might not be able to believe that his wife, the person he loves, could betray him. But once the truth sinks in, he would start to analyze the situation carefully. He might try to find a way to redeem her, depending on the nature of the betrayal, as he always believes in the power of forgiveness and second chances.
One idea could be that their own village betrays them. Maybe there's a power - hungry leader who sees Naruto and his sister as threats to their new regime. They could be framed for a crime they didn't commit and then forced to flee the village. In the process, they might have to rely on some unlikely allies they meet on their journey, like a group of outcasts who also have a grudge against the village.
Naruto's power might also be affected. If he was betrayed, he could lose the will to fight or train. He might even start to doubt his own purpose. This could lead to a decline in his abilities, which in turn could put the village at risk if he was its main protector.
His reaction would depend on how the betrayal was presented. If it was a sudden revelation, he would be shocked and devastated. He may start to question his own worth, thinking that if his own parents could betray him, what was wrong with him? He could also become more reckless in his actions, not caring about the consequences as much since he felt like he had already lost the most important thing. This new Naruto could also be more empathetic towards the villains in the story, understanding their feelings of being wronged or betrayed in some way.
He could then feel a deep sense of anger. Naruto has a temper, especially when it comes to those he loves. He might vow to find out the reason for the betrayal and make things right, or if it was truly malicious, seek revenge in his own Naruto - like way, which would involve trying to understand the person's motives even while being angry.
He would likely feel a great sense of anger. Naruto has a strong will, and this betrayal would fuel his anger. He might be determined to find out the truth and get revenge on those who wronged him. At the same time, he would also be in deep pain. It's like losing the most important thing in his life. This emotional turmoil could lead to a change in his personality, making him more withdrawn and less optimistic than before.
At first, Naruto would likely be shocked. He has always been so loyal to his team, and this sudden betrayal would be a huge blow. He might stand there in disbelief, unable to process what's happening.