In some Dramione fanfictions, Draco might betray Hermione by revealing her Muggle - born status in a way that endangers her. In the wizarding world, there are still some pure - blood supremacist ideas floating around. If he discloses her background to the wrong people, it could put her in serious jeopardy. He could also betray her by going back on a deal they made. For example, if they made a pact to work together to reform Hogwarts' curriculum to be more inclusive, but then he breaks the deal and sides with the more traditionalist professors.
Well, it could be that Draco betrays Hermione's academic trust. Since they are in a world where magic and knowledge are highly valued, he might steal her research or ideas for a spell or a magical discovery. This would be a huge betrayal as Hermione values her intellectual pursuits greatly. Also, he could betray her trust regarding a secret mission they are on together. He might abandon her in a dangerous situation, like in a dark forest full of dangerous magical creatures or in an old, enchanted castle filled with dark magic traps, just to save his own skin.
One possible scenario could be a character being betrayed by a teammate. For example, Ruby might be betrayed by Weiss if Weiss is lured to the dark side by some powerful and evil force. This could lead to intense battles and emotional turmoil for Ruby.
Well, in this type of fanfiction, it might be that Twilight Sparkle is betrayed by a mentor figure. This mentor could have been teaching her false information all along, causing her to make mistakes that put her and her friends in danger. Or it could be that she is betrayed in a love - related situation. For example, if she has feelings for a certain pony and that pony pretends to reciprocate only to use her for something else, like getting access to the library in Canterlot. There are so many directions this fanfiction could take.
Perhaps in the fanfiction, Danny is betrayed by a new ally he trusted. This new character could have joined Danny in his fight against evil ghosts, but in reality, they were working for a more powerful and evil ghost all along. They might use Danny's trust to learn about his weaknesses and then expose him to danger, leaving Danny feeling hurt and alone, having to reevaluate who he can trust in the future.
Perhaps in the fanfiction, Naruto is betrayed by a new character introduced. This character could be very charming and deceive everyone in the community into thinking Naruto has done something wrong. The character might be secretly working for an old enemy of Naruto's. They could fake evidence of Naruto's betrayal, like showing false images or documents, which would cause the community to turn their backs on Naruto.
Perhaps Bell Cranel is betrayed by someone he trusts in a love interest situation within the fanfiction. For example, his romantic partner might be using him for their own gain and then betrays him when they get what they want.
One possible scenario could be Naruto being forced into a situation where he has to seem to betray Sakura to protect her from a greater danger. For example, he might be blackmailed by an enemy into staying away from her or acting against her interests.
In Camp fanfiction, Percy could be betrayed when the camp leaders are deceived by false evidence against him. Let's say an enemy creates some fake proof that Percy has been colluding with their side. The leaders, without fully investigating, might turn on Percy. Also, there could be a love - related betrayal. If Percy has a romantic interest in the camp, the person he likes could be forced by their family or some external pressure to break Percy's trust and use his feelings against him, for example, to make him give up his position in the camp or some important secrets.
One possible scenario could be that Ash betrays May for a powerful Pokemon. Maybe he gets offered a super rare and strong Pokemon but has to cut ties with May to get it. Another could be that May betrays Ash because she is influenced by a rival trainer who convinces her that Ash is holding her back from reaching her true potential as a Pokemon trainer.
She might become extremely angry and cut off all ties with Draco immediately. Hermione is a strong - willed character, so she would not tolerate betrayal easily. She could use her magic to create some sort of barrier between them, magically locking him out of her life.
She might become more distrustful. After being betrayed, it's natural for her to have a hard time trusting others again.