Sasuke is a likely candidate in some fanfictions. Given their complex relationship throughout the original series, it's easy to imagine a scenario where Sasuke's thirst for power or some misinformation leads him to betray Naruto. Another could be Sakura. If she becomes jealous of Naruto's growing power or if she's manipulated by outside forces, she might turn against him.
Some fanfictions explore the idea of Naruto being betrayed by a new character introduced into the story. This new character could be secretly working for an enemy and manages to turn Naruto's closest allies against him by using their insecurities. This creates a complex web of relationships where Naruto has to fight not only the external threats but also the internal ones within his group.
One common theme is trust. When there's betrayal in the harem, it often shatters Naruto's trust in those he cared about. For example, a member of the harem might betray him for the sake of a hidden agenda.
One popular 'betrayal naruto fanfiction' is where Sasuke's betrayal takes a different and more extreme turn. In some stories, he teams up with unexpected enemies against Konoha, which creates a whole new set of conflicts and power dynamics. Another one could be about Naruto being betrayed by his so - called friends in the village due to false accusations, leading him to question his loyalty to Konoha.
Naruto would be deeply hurt by the betrayal. He has a big heart and values his relationships. He would feel confused as to why Serafall would turn on him. This might cause him to question his own judgment in trusting people. But being Naruto, he would not let this break him. He would rise above it, perhaps trying to talk to Serafall to clear up any misunderstandings. If that fails, he would focus on his own path, becoming stronger both physically and mentally, all while still holding out a little hope that things could be set right between them in the future.
He could feel a great sense of anger and sadness. Naruto has a big heart, and being betrayed by someone he considered a friend or ally would be deeply hurtful. He might start to question his own judgment in trusting Mavis. And then, he would likely try to find out the reason behind the betrayal. He's not the type to just let it go. He would pursue the truth, whether it's to get revenge or to clear up any misunderstandings.
Naruto would probably be initially shocked. He always tries to see the good in people and would not expect such a thing from Mei. He might try to talk to her to understand why she did it.
At first, Naruto would probably be extremely shocked and in denial. He has always looked up to Kakashi as a mentor and friend, so the idea of being betrayed by him would be hard to accept immediately.
Naruto would probably be extremely hurt. He is someone who values friendship and trust deeply. So, he might initially be in shock and disbelief. He would likely feel angry too, but his anger might be mixed with sadness.
Naruto himself could be a victim of family betrayal. His father Minato or mother Kushina might be involved in some alternate - universe plot where they turn against him for some dark reason. Sasuke's family is also a likely candidate. Itachi's actions could be re - imagined in a way where his real motives are more about betrayal of the Uchiha family rather than protecting it. And Hinata's family might be involved too, like if Neji, before his death, was made to betray the Hyuga family in some fan - created scenario.