Perhaps Harry Potter travels back in time and, for some reason, makes a deal with the dark side. He might be tricked into believing that by siding with Voldemort in the past, he can save more lives in the future. This betrayal could lead to a whole new chain of events, changing the relationships he has with his friends like Ron and Hermione.
In a time - travel scenario where Harry betrays, it could be that he goes back to a crucial moment in wizarding history and, due to his knowledge of future events, decides to change things in a way that benefits him personally but goes against the greater good. For example, he could try to prevent the creation of certain magical laws that he sees as restricting his power later on. This would cause a rift between him and the wizarding community, including his allies. His friends would then be faced with the difficult decision of whether to side with him or oppose him.
One possible plot could be that the godlike fem Harry Potter is betrayed by the wizarding establishment. They see her as a threat due to her immense power. So they conspire against her, which leads her to go into hiding. While in hiding, she discovers secrets about the wizarding world that were meant to be hidden and she uses this knowledge to fight back against those who betrayed her. She may also form new alliances with outcasts or creatures that were also wronged by the wizarding society.
One possibility could be that Ichigo is betrayed by a close friend during his time - traveling adventures. Maybe this friend is jealous of Ichigo's powers or has been influenced by an enemy. This betrayal could lead Ichigo to question his relationships and his purpose in the time - traveling journey. He might then have to find a way to overcome this betrayal and still fulfill whatever mission he has in the different time periods.
Well, perhaps in this fanfic, Harry could be wrongly accused of a serious crime like dark magic use. Everyone, including his friends Hermione and Ron, might turn their backs on him due to false evidence. He would then have to fight alone to clear his name and find out who really framed him.
In a 'Harry Potter betrayed by Gryffindor' fanfiction, perhaps there is a prophecy that is misinterpreted. The Gryffindors think Harry is the cause of upcoming doom instead of the savior. So, they begin to betray him. Harry would then have to struggle not only with the external dark forces but also with the internal pain of being rejected by those he considered friends and housemates. He might start to question his own identity and values, and his journey would be about regaining the trust of Gryffindor or finding his own path without them.
The plot could center around Harry finding a mysterious spell that transports him to the 1940s. Once there, he discovers that the actions of a certain dark wizard in that era are linked to future threats he faced in his own time. So, he tries to stop this dark wizard's plans.
One possibility could be that during his time travel, Ichigo discovers that his friends or allies in the future have turned against him for some reason. Maybe they believe he has become too powerful and is a threat. So they plot to betray him, which sets up a conflict where Ichigo has to fight against those he once considered friends while also trying to figure out a way to fix the timeline.
In a 'Harry Potter betrayed fanfic', perhaps Hermione turns against Harry. It could be because she disagrees with Harry's more dangerous and reckless plans to fight Voldemort. She might think he's endangering too many lives without proper thought, and this leads to a rift and a sense of betrayal.
Perhaps in the fanfiction, the Quidditch team gets influenced by a dark wizard who has a grudge against Harry. The wizard uses a spell to make the team members believe Harry is a threat to them. So they start to betray him by not passing the Quaffle to him during the game, or even colliding with him on purpose during a fly - around. This would lead to Harry feeling extremely isolated and confused as he thought his team was like family.
Well, perhaps in this fanfiction, Percy Jackson is sent on a time - travel mission by the gods. But he discovers that his friends or allies have betrayed him. Maybe they've made a deal with an enemy from another time period. For example, they could have promised to help Kronos in the past in exchange for power in their own time. Percy then has to not only deal with the time - travel chaos but also face the betrayal and find a way to set things right.
In this fanfiction, the plot might revolve around Harry's transformation into a mob boss during time travel. He could discover that the wizarding world has a seedy underbelly that was hidden from him before. Harry may start to use his magic in new and unethical ways to gain power. He might face challenges from other powerful wizards who don't want a new player in the mob scene. His friends, like Hermione and Ron, could be conflicted about whether to support him or try to stop his descent into the dark side of the wizarding world.