A typical plot twist might be that Spider - Man's friends are actually part of a secret organization that has an agenda against superheroes in general. They might see Spider - Man as a threat to their plans. Another scenario could be that they were bribed by a powerful figure to betray Spider - Man. This figure could have promised them wealth, power, or something else they desired. In some fanfictions, his friends might betray him because they are under the influence of a powerful and evil magic or technology that alters their personalities and loyalties.
One common plot twist could be that Spider Man was actually framed for the kidnapping. Maybe a villain set him up to make him look bad in the public eye while they carry out their real evil plan. Another could be that the person he 'kidnapped' is actually a secret enemy who has been manipulating events all along.
He would be very hurt. He might isolate himself for a while, doubting his own judgment in trusting his friends. Spider - Man might also start to question his identity as a hero. After all, if his friends can turn on him, what does that say about his relationships and his role in the world?
One common plot twist could be Batman being betrayed by a close ally like Robin. Maybe Robin gets brainwashed by a powerful villain and turns against Batman. Another could be Batman's trusted butler Alfred being forced to betray him under some extreme threat. For example, a villain might hold Alfred's family hostage and make him leak Batman's secrets.
One common plot twist could be that the Black Cat steals something crucial from Spider - Man that he was relying on to defeat a major villain. For example, she might take a new piece of tech he was going to use against a powerful enemy, leaving him at a disadvantage. This would add drama and conflict to the story.
One common plot twist could be that a close friend or ally, who Ichigo thought he could trust completely, turns out to be working for the enemy all along. For example, Orihime might be brainwashed by a powerful Hollow to feed information about Ichigo's whereabouts and plans to the Hollows. Another could be that the Soul Society, which Ichigo has often helped, decides to turn on him due to some false accusations of him being too dangerous. Maybe they believe he is on the verge of losing control of his Hollow powers and decide to eliminate him before he becomes a threat to both the living world and the Soul Society.
Another possibility is that Edward betrays Bella by revealing her secrets to their enemies. Maybe he was forced to do so under some sort of blackmail from a powerful and malicious vampire or other supernatural being. In this case, Bella would have to face the consequences of having her secrets exposed while also dealing with Edward's betrayal.
One common plot twist could be that the person she trusts most, like her best friend, betrays her for power. Maybe her friend is offered a high - ranking position in a magical guild or something and has to sacrifice Lucy to get it. Another could be that a love interest betrays her. He might be secretly working for an enemy and using Lucy to get information about her family or her magic.
Another plot twist could be that Percy discovers he has some hidden power or heritage as a result of the betrayal. For instance, he might find out that he has a connection to an ancient and powerful force that the gods were afraid of, which is why they betrayed him. This new power then becomes a key element in his journey to either seek revenge or prove his worth.
One example could be a story where Spider Man is betrayed by his friends in the Avengers. Maybe they suspect him of a crime he didn't commit due to some false evidence planted by a villain. Another could be a scenario where his love interest, like Mary Jane, betrays him by revealing his secret identity to the media out of jealousy or being manipulated.
A great plot twist could be that the main villain turns out to be a seemingly innocent character from one of the dimensions. For example, a friendly neighborhood Spider - Man's sidekick who has been secretly manipulating events all along to gain ultimate power in the spider - verse.