What are the possible reasons for Arceus betraying Ash in fanfiction?

It could also be due to some external influence. Perhaps an evil organization has manipulated Ash in some way, forcing him to act against Alola. They might have used mind control or blackmailed him with something he holds dear, like the safety of his Pokémon.

One possible plotline could be that Ash is raised by Arceus to be a sort of Pokémon messiah. He is taught the true essence of Pokémon and is sent on a quest to save the Pokémon world from an impending doom.

Another plot could be that Arceus is in some sort of trouble and Ash is the only one who can save it by capturing it. This could involve a complex story where Ash has to figure out what's wrong with Arceus and how to use his skills to capture it in a way that helps it.

One possible plotline could be that Ash is influenced by a powerful and evil force. This force convinces Ash that Cynthia is somehow a threat to his ultimate goal, like becoming the greatest Pokémon trainer. So, he betrays her by stealing a crucial Pokémon of hers during a big tournament. This would lead to a lot of drama and conflict as Cynthia would be shocked and heartbroken, and Ash would start to realize the error of his ways as the evil force begins to control him more.

In some fanfictions, Percy might betray Natasha due to his own ambition. He could see an opportunity to gain more power or status by siding against her. For example, if there's a power struggle within their group or world, and he thinks that by betraying Natasha, he can get on the winning side and be rewarded. It could also be a case of jealousy. If Natasha has always been in the spotlight or has more skills and abilities, Percy might feel overshadowed and his jealousy could lead to betrayal.

It could be because of a power struggle. Suppose Naruto discovers a new, extremely powerful power within himself, but the village elders or some members of Team 7 are afraid of it. They try to suppress him. Feeling cornered and betrayed first, Naruto could then turn against them. He might believe that he has to protect this new power and use it for what he thinks is right, even if it means going against his old team.

Perhaps Natsu feels betrayed by the guild first. There could be a situation where he believes the guild has turned its back on one of his closest friends or on a principle he holds dear. This sense of being let down by the guild might lead him to take extreme actions that seem like betrayal. It could also be related to a power struggle. If there's a new power within the guild that Natsu sees as a threat to the guild's original values, he might try to oppose it in a way that looks like betrayal from the outside.

It could be that Arceus betrays Ash by revealing that all of Ash's Pokemon encounters and relationships were fabricated. Arceus made it so that Ash would form bonds with certain Pokemon to further its own ends. For instance, Arceus wanted to study the power of friendship among humans and Pokemon through Ash's experiences. When Ash finds out, he feels used and betrayed. He might then set out on a journey to free his Pokemon from Arceus' control and restore their true free will.

I'm not sure specifically if there is an existing fanfiction with that exact title, but it's a very possible concept in the Pokémon fanfiction community. Writers might explore Ash's darker side in relation to Korrina, perhaps due to a conflict over different ideologies within the Pokémon world, like how to train Pokémon or what the true purpose of battling is.

A frequent theme is Ash's growth and development. When paired with Arceus, Ash is often put in extraordinary situations that force him to become stronger, both as a trainer and as a person. Also, the theme of good vs. evil is quite common. Arceus, being a symbol of good in the Pokémon universe, teams up with Ash to fight against various forms of evil, such as evil Pokémon organizations or dark, power - hungry trainers.