Well, often in such a 'ash gets betrayed fanfiction', the story might start with a seemingly normal day for Ash. Then, out of the blue, someone he trusts deeply, like Pikachu or one of his human friends, does something that he perceives as a betrayal. This could be something as simple as not believing in him during a crucial battle or siding with an enemy for a reason that's not clear to Ash at first. It can create a lot of emotional turmoil for Ash and make for a very engaging read.
One possible reason for Ash getting betrayed in the fanfiction could be misinformation. A villain might spread false rumors about Ash, making his friends believe he has done something wrong. His friends, without verifying the truth, turn against him. It's a sad situation where lack of communication and trust plays a big role.
A plotline might involve Ash being betrayed by a new acquaintance he meets on his journey. This person could pretend to be his friend, gain his trust, and then use that trust to steal his Pokémon or important items. Or perhaps Ash is betrayed by a Pokémon he just caught. The Pokémon could have been planted by an enemy trainer to spy on Ash and then turn on him at a crucial moment.
The story could end with Ash forgiving everyone. Despite the betrayal, he realizes that his friends were misled or acting out of weakness. So he takes them back and they all learn from the experience, growing stronger together.
One possibility could be that in the fanfiction, Ash betrays Latias out of a misunderstanding. Maybe he was tricked by a villain into believing that Latias was a threat to the region. This would create a lot of drama and conflict in the story as Latias, who probably trusted Ash, would be deeply hurt.
In fanfiction, a story about Ash and Latias being betrayed could be really heart - wrenching. Maybe it could involve Ash being wrongly accused by his friends and Latias being forced to turn against him due to some dark magic or false information. It might explore themes of trust and friendship being broken.
One possible revenge scenario in the fanfiction could be that Ash was betrayed by a close friend in a Pokémon journey. Maybe his so - called friend stole his Pokémon. So, in revenge, Ash might train harder, find new and powerful Pokémon, and then challenge his betrayer in a huge battle. He could use his new skills and Pokémon to defeat the one who wronged him, regaining his honor and his Pokémon.
Ash could get angry. He has a strong sense of justice, and he might feel that May has violated their friendship. He could challenge her, not in a violent way, but more in a way to get an explanation and to try to make her see the error of her ways. He would likely be determined to show her that what she did was wrong.
Ash would be extremely devastated. Pikachu is not just his Pokémon but also his closest friend. He would likely first try to reason with Pikachu, not believing that Pikachu could truly betray him. He might be in denial for a while.
He might be initially shocked. Ash has always been surrounded by friends and supporters, so suddenly being betrayed by everyone would be a huge blow. He could be in disbelief for a while.