One possible way this could develop is through a misunderstanding. Maybe Naruto is framed for a crime he didn't commit, and his friends believe the false evidence against him. For example, an enemy could plant evidence that makes it seem like Naruto is working with the villains. His friends, not knowing the truth, turn their backs on him. This would lead to Naruto feeling extremely hurt and isolated, and he might have to go on a journey to prove his innocence on his own.
It could be that Naruto's newfound power scares his friends. Let's say he discovers a powerful and somewhat dark ability. His friends, fearing he might lose control or be corrupted by it, decide to betray him to protect the village. However, Naruto has no intention of using the power for evil. This would create a situation where Naruto is both betrayed and misunderstood, and he would have to fight not only to regain his friends' trust but also to show that the power can be used for good.
In a fanfiction scenario, a prophecy might be misinterpreted. The prophecy could be related to Naruto in a way that his friends misunderstand. They might think Naruto is the cause of an upcoming disaster instead of the solution. So, they betray him to try and prevent the disaster. But as the story unfolds, it becomes clear that they were wrong, and Naruto was actually the key to saving the day all along.
In this kind of fanfiction, one way it could develop is that Minato might be under some kind of dark influence. Maybe an enemy has a powerful genjutsu that makes Minato see Naruto as a threat to the village instead of his son. This would lead to actions that Naruto perceives as betrayal. Naruto, being the strong - willed character he is, would likely be extremely confused and heartbroken at first. He would then probably try to find out the real reason behind Minato's actions, starting his own journey of discovery.
In some fanfictions, Tsunade might betray Naruto due to political pressure. Maybe the village elders force her hand, believing Naruto's power is too dangerous. It could also be a misunderstanding, like false information about Naruto being a threat to the village reaching Tsunade.
One way this could develop is if Naruto's identity as the Jinchuriki of the Nine - Tails is fully exploited against him. People might fear his power and turn on him. For example, the village elders could spread false rumors about him losing control of the Nine - Tails, causing the villagers to shun him. Another possibility is that a powerful enemy uses mind - control or deception to make those close to Naruto, like Sakura or Kakashi, turn against him. This would be a huge blow to Naruto as he values his relationships deeply.
In a fanfiction where Naruto is betrayed by his friends, it could start with jealousy. Suppose Naruto gets a great power or a special recognition. His friends, feeling overshadowed, might be tricked by an evil force into thinking Naruto is using them. So they betray him, which makes Naruto realize that he has to rely on his own strength and find new allies who truly understand him.
Sometimes in fanfictions, character development takes a dark turn. The friends might have their own personal goals that conflict with Naruto's. They could see Naruto as an obstacle to achieving those goals. Or perhaps there was a long - hidden secret that came to light, which made them change their attitude towards Naruto, leading to the so - called betrayal.
In a fanfiction like this, it could be that Percy's powers or abilities were starting to make others jealous. His friends might have felt overshadowed and, in a moment of weakness, turned on him. Also, there could be an outside influence, like a dark force that was manipulating people's minds to make them betray Percy.
One way it could develop is if Dumbledore withholds important information from Hermione about her family or her own magical abilities. He might do this because he fears she will use that knowledge in a way that could disrupt his grand plan for the wizarding world. For instance, Hermione discovers she has a special power that could defeat Voldemort easily, but Dumbledore has kept it from her all along, making her feel extremely betrayed as she could have saved many lives if she knew earlier.
He could be betrayed by a false friend in the DxD world who spreads lies about him. For instance, telling others that Naruto has a hidden agenda to take over their realm.
Well, in fanfiction, the author might create this situation to explore new storylines. Maybe the author wants to show Naruto's vulnerability. Erza could be made to betray Naruto due to some misinformation or a dark influence. For example, if there's an evil force that manipulates Erza into believing Naruto is a threat to her world or friends.
In some fanfiction, this could happen due to a misunderstanding. Maybe Hinata is forced into a situation where she has to seem like she's betraying Naruto. For example, she could be blackmailed by an enemy who threatens the safety of the village or her family. Another possibility is that there is some sort of mind - control involved that makes her act against Naruto.