It could be a rival trainer. Rival trainers are often very competitive in the Pokémon world. Maybe this rival is jealous of Ash and May's progress and decides to betray them to slow them down. They might spread false rumors about Ash and May, causing other trainers to be distrustful of them.
The main characters are Ash and May, of course. Ash is a well - known Pokemon trainer with a passion for catching and training different Pokemon. May is also a trainer who has her own goals and journey in the Pokemon world. In this fanfiction, their relationship takes a turn due to the betrayal aspect.
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.
In such a fanfiction, they might be betrayed by a so - called friend. For example, a fellow trainer could steal their Pokémon in order to gain an advantage in a big tournament. This would be a huge shock to Ash and May, and they would have to figure out how to get their Pokémon back and also deal with the sense of betrayal.
One possible analysis could be that in such a fanfiction, the idea of Ash being betrayed might be a way to create drama. It could involve his friends or companions in the harem turning against him for various reasons like jealousy or misinformation.
Well, sometimes the antagonist can be an internal struggle within Ash or May themselves. For example, Ash's over - ambition to become the best Pokémon trainer might lead him to make choices that seem like a betrayal to May. His single - minded focus on winning battles and collecting badges could make him neglect May's feelings. In this case, Ash's own ambition is acting as the antagonist in the story. Similarly, May's insecurities could make her misinterpret Ash's actions as betrayal, and her insecurities then become the antagonist in the relationship.
It could be his rivals. For instance, Tracey or Paul might see Ash's potential in the new region as a threat and decide to betray him. They could try to sabotage his battles by giving false tips to his opponents or stealing his battle strategies.
Ash would be extremely hurt. He's a very loyal person, and having someone he cares about like Lillie betray him would be a huge blow. He might initially go into denial, not believing that Lillie could do such a thing.
In many such fanfictions, the plot might involve Ash's friends suddenly turning against him due to some false accusations or misunderstandings. For example, they could believe that Ash has been secretly working with an enemy group, which leads to his betrayal.
Well, it might be that his rivals in the fanfiction somehow manage to deceive his Pokemon into thinking Ash is a bad trainer. Maybe they spread false rumors about how he doesn't really care for them, which causes the Pokemon to betray him. This would shatter Ash's world as his Pokemon are his closest friends and partners.