Perhaps Naruto's family discovers some false information about Naruto being involved in something evil. Without proper investigation, they immediately turn against him. Maybe an enemy of Naruto fabricated evidence to make his family believe he was a traitor. This would lead to a very heart - breaking betrayal for Naruto, as his own family didn't trust him enough to find out the truth first.
One possible plot could be that Naruto's family, perhaps his father or mother, were actually alive but had to fake their deaths for some dark reason. Then they reappear and turn against Naruto, maybe because they are being controlled by an evil force. Another plot might be that his family had some long - hidden secrets that made them see Naruto as a threat to their real goals, so they betrayed him.
One possible plot could be that Boruto is betrayed by his friends due to a misunderstanding. For example, they might think he has turned to the dark side because of some false evidence planted by an enemy. Another could be that Boruto is betrayed by the village he loves. Maybe the village leaders suspect him of a crime he didn't commit and turn against him.
In some fanfictions, there might be a plot where Kakashi's past traumas are related to Naruto's current challenges. For instance, Kakashi's experience with losing his comrades could be used to help Naruto deal with the potential loss of his friends. Or perhaps a plot where Kakashi's family secrets are revealed and they have a significant impact on Naruto's growth as a ninja. This could involve a hidden jutsu or a prophecy that ties them together.
It could be that the whole Team 7 is brainwashed by an evil ninja with powerful genjutsu abilities. They are made to believe that Naruto is the key to a great evil that will destroy the ninja world. As a result, they turn on Naruto, and he has to fight not only his former teammates but also the false accusations and the real threat behind the brainwashing.
One possible plot could be that Konoha's leaders, fearing Naruto's growing power, secretly plan to get rid of him. They spread false rumors about him, turning some of the villagers against him. Another plot might be that they frame Naruto for a crime he didn't commit, perhaps a major attack on the village, in order to justify exiling or imprisoning him. A third possibility is that they withhold important information from Naruto that could put his life in danger, all in the name of protecting the village's secrets.
One possible plot could be that Tails is betrayed by a close friend who becomes jealous of his intelligence and skills. For example, Sonic might start to feel overshadowed by Tails and in a moment of weakness, turn against him. This could lead to Tails having to fend for himself and prove his worth all over again.
One possible plot could be that Fleur betrays Harry in a Triwizard Tournament - related task, perhaps by secretly helping the other champions. Another might be that Harry discovers Fleur has been passing information about the Order of the Phoenix to the wrong side. Maybe Fleur betrays Harry's trust regarding a personal secret, like his feelings for Ginny, and uses it to her advantage in some way.
In some 'Wei Wuxian betrayed fanfiction', it might be that he is betrayed by a family member or a disciple he had trained. For example, they might side with his enemies in a battle, believing the lies told about Wei Wuxian's so - called 'evil ways'. This would make Wei Wuxian feel extremely hurt and isolated, having to face the challenges alone.
One possible plot could be that Ash discovers Anabel has betrayed him by siding with a rival trainer in a crucial tournament. This could lead to a rift in their friendship and Ash having to find a way to overcome this setback and prove himself without her support.
One possible plot could be that Mega Man is betrayed by his creator. Maybe the creator decides Mega Man has become too powerful and tries to shut him down, leading Mega Man to fight for his own survival while feeling deeply hurt by the betrayal.
One possible plot could be that everyone believes false rumors about Harry being a dark wizard. His friends from Hogwarts, including Ron and Hermione, turn their backs on him. Harry then has to find a way to prove his innocence all alone, perhaps by going into hiding and secretly investigating who spread the lies.