There might be some new characters introduced in the fanfiction. A mysterious Pokemon trainer who has some ancient knowledge about Arceus and can guide Ash. Or perhaps a group of Pokemon researchers who have been studying the relationship between Arceus and the world for a long time. These characters could add more depth to the story, providing different perspectives on the situation between Ash and Arceus, and helping Ash in his fight against the perceived betrayal.
Well, it could be that Ash makes a discovery that goes against Arceus' grand plan and is thus betrayed. Maybe he finds out something about the balance of the Pokemon world that Arceus doesn't want known.
In a fanfic where Ash betrays and captures Arceus, it could be a very dark and unexpected turn. Maybe Ash has been influenced by some powerful and malevolent force. This would completely change his character archetype from the heroic trainer we know. It could lead to a lot of chaos in the Pokémon world as Arceus is like a god in that universe.
Ash would likely be extremely heartbroken. He has always had a deep connection with Pokemon and believing that Arceus, a powerful and supposedly benevolent being, has betrayed him would be a huge blow. He might become withdrawn at first, not knowing who to trust anymore.
Perhaps Ash has been deceived by a false prophecy or a mysterious figure. This false information could lead him to believe that capturing Arceus is the only way to save the Pokémon world from an impending doom. So, in his misguided attempt, he betrays Arceus.
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 exactly how many fanfictions exist where Ash is the son of Arceus, but it's a very interesting concept. It could lead to all kinds of plot twists. For example, Ash might have some hidden powers or a special connection to the Pokémon world that others don't. This kind of fanfiction can explore the relationship between Ash and Arceus in ways that the original series doesn't.
In 'ash raised by arceus fanfiction', one could expect a lot of creative elements. For example, Arceus being a god - like Pokémon might raise Ash in a way that completely changes his understanding of the Pokémon world. It could involve Ash learning secrets about Pokémon that no one else knows, and this might lead to new adventures and challenges for him.
Yes, there are quite a few. You can find some on popular fanfiction websites. Some might focus on Ash's epic journey to catch Arceus, with detailed battles and his growth as a trainer along the way.
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.