Gary Oak is a likely character. He has always been a rival to Ash and in fanfiction, he might betray Ash out of jealousy or a desire to be the ultimate Pokémon trainer. Another could be Misty. Maybe she gets influenced by some external force or her own insecurities and turns against Ash. Brock could also be a candidate in some stories. If he falls in love with a girl who has a vendetta against Ash, he might be forced to choose between his loyalty to Ash and his new love interest.
In 'pokemon ash betrayal fanfiction', Jessie, James, and Meowth from Team Rocket are often the ones to betray Ash in a different way. Instead of their usual comical attempts to steal Pikachu, they could form a more devious plan where they pretend to befriend Ash only to double - cross him later. Also, some fanfictions might have Professor Oak betraying Ash. He could be hiding some dark secrets about Ash's past or Pokémon in general and use Ash for his own experiments without Ash's knowledge.
Their closest friends like Brock and Misty would surely be affected. They've been through so much with Ash, and his betrayal would be a huge shock. And for Lyra, her friends in her own region might be deeply hurt.
Gary could be a likely character. He has always been Ash's rival and there could be a plot where his jealousy or some other motive leads him to betray Ash. Another could be one of his so - called friends from the Pokemon League who might be influenced by power or some dark secret. Or, in some really dark fanfictions, it could be a Pokemon that Ash trusted deeply but for some reason turns on him.
Some fanfictions might have Misty betray Ash. Perhaps she gets lured by the promise of power or some valuable reward. She could be tricked into believing that Ash is no longer the friend she thought he was and that betraying him is for the greater good.
In certain fanfictions, a Pokémon professor or an authority figure in the Pokémon world could betray Ash. They may have their own secret agendas. For example, a professor might use Ash's research data without his permission or manipulate him into dangerous situations for their own experiments. This would make Ash feel extremely betrayed as he looks up to these figures for guidance.
In fanfiction, Gary could be a likely character to betray Ash. He has always been a rival and might have ulterior motives. For Dawn, Zoey could potentially betray her. Zoey has been a tough competitor and might be jealous enough to take some underhanded actions. Another possible betrayer for Ash could be Team Rocket. They've been after his Pikachu for a long time and could use betrayal as a new tactic. For Dawn, perhaps a new coordinator who is envious of her popularity in the coordinator world.
One likely character could be a rival trainer. They might see Fem Ash as a threat and betray her to get an edge in competitions. Another could be a so - called friend who is jealous of Fem Ash's success.
He'll surely meet the Alola region's professors. Also, the local trial captains are very likely to cross paths with Ash. And of course, the regular Pokémon trainers in Alola.
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.
Obviously, Ash would be the main character since he's the one collapsing. His Pikachu would most likely be a key character as well. Pikachu is always by Ash's side and would probably be very concerned and try to help when Ash collapses.
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.