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.
Jiang Cheng could potentially be the one to betray Wei Wuxian in some fanfictions. Their relationship has always been complex, and with some twists in the plot, Jiang Cheng might be influenced by the outside world or his own insecurities to turn against Wei Wuxian.
One possible plotline could be that Wei Wuxian discovers he has a unique ability or curse that results in him being able to give birth. This then leads to a journey of him coming to terms with this new reality and the reactions of his friends and loved ones.
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 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.
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.
One possible plot could be Percy being framed for a crime he didn't commit by the Olympians. Maybe they needed a scapegoat for something that went wrong in the mortal world that they didn't want to take the blame for. Another plot might involve Percy discovering a dark secret about the Olympians that they don't want him to reveal, so they turn on him to keep him silent. It could also be that a new powerful enemy has influenced the Olympians against Percy, perhaps by spreading false rumors or using some form of mind control on them.
Maybe there's a prophecy at camp that some misinterpret to mean Percy will bring destruction. So, the campers, out of fear for their safety, betray Percy. They could lock him up or try to send him away, even though Percy has always been loyal to the camp. He then has to find a way to either clear his name or find a new place where he belongs.
Perhaps in the fanfiction, Natsu is betrayed by someone he trusts in a mission. For example, they might leave him behind in a dangerous situation to fend for himself while they take the credit for the mission. Or it could be that a love interest betrays Natsu by choosing someone else over him due to some false perception or external pressure.
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 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.