Well, at first, it would be a bit of an adjustment for both of them. Pikachu is used to following Ash's lead, but now with Ash as an Eevee, Pikachu has to be more proactive. He might start teaching Eevee - Ash things that he learned from their previous adventures. Their relationship could also become more equal in some ways, as Eevee - Ash would have his own new abilities and perspectives to bring to their partnership.
His relationship with Pikachu would become quite different. Pikachu might have to take on a more protective role. Instead of Ash being the one in charge, Pikachu would be looking out for Eevee - Ash. They would still have a strong bond, but it would be based more on Pikachu's guardianship now.
In the fanfiction, when Ash becomes an Eevee, his relationship with Pikachu is bound to change. Pikachu would be confused at first but then would quickly adapt. Since Eevee are generally smaller and more vulnerable compared to a human - like Ash, Pikachu would be constantly on guard. Their communication might also change. Eevee - Ash might communicate in different ways than before, and Pikachu would have to learn to understand these new signals. Over time, they would develop a new dynamic where Pikachu is the more experienced and protective partner, while Eevee - Ash is learning and growing in this new form.
His relationship with Pikachu might become more competitive at first. Since Ash already has a strong starter in Charmander, Pikachu might feel the need to prove itself more. But over time, they could learn to work together better, with Pikachu using its electric attacks to complement Charmander's fire attacks in battles.
At first, Ash and Eevee might be a bit cautious around each other. Ash is excited to have caught a new Pokémon, but Eevee is in a new and strange environment. As they start training together, they build trust. Eevee might learn new moves from Ash's guidance, and Ash learns more about Eevee's unique abilities.
It makes his relationship with other trainers rather unique. Other trainers might view Ash with a mix of awe and envy. Since he was raised by Legendary Pokemon, they may assume he has some special training methods or insights. Some trainers might be eager to learn from him, while others could be intimidated and see him as a rival to be defeated at all costs.
Well, perhaps Ash starts to idolize Pikachu after seeing its unique powers in a battle. He might try to imitate Pikachu's moves and even start collecting Pikachu - themed items.
One popular type of Pokemon Ash and Pikachu fanfiction might be adventure - based. For example, Ash and Pikachu could embark on a journey to a new and mysterious region filled with undiscovered Pokemon species. They might face challenges like difficult terrains and powerful, previously - unseen Pokemon. In this fanfiction, Pikachu's electric powers could be enhanced in some unique way, and Ash would have to strategize differently to overcome the obstacles.
It could be a trainer who hates Pikachu and wants to capture all of them. This would put Ash, as a Pikachu fan, in direct conflict with this trainer.
Another way is to create a character with a mysterious past that ties into the world of Pikachu and Eevee. Maybe the character was once part of a secret experiment that involved the powers of Pikachu and Eevee. This backstory could drive the character's actions and decisions throughout the fanfiction. They could be on a quest to find out more about their past while also interacting with Pikachu and Eevee. This character could have unique skills or knowledge that they share with Pikachu and Eevee, making the story more engaging. For instance, they might know a special training method for Eevee to quickly evolve into its most powerful form. And they could also have a special bond with Pikachu, like being able to communicate with it on a deeper level than normal trainers.
His Pokémon might be really confused at first. They're used to Ash as a human, so seeing him as a Pikachu would be quite a shock. But some of them, like Pikachu himself, might feel a closer bond since Ash is now in a similar form.
His Pikachu would probably be very supportive. It would stay by his side as he studies, maybe even help him in small ways like fetching medical tools. It trusts Ash completely and would be happy to see him pursue something new.
His Pikachu might feel a bit jealous at first. But eventually, they would all accept Mew as part of the team. Ash would have to spend more time getting to know Mew's unique abilities, which might mean less training time for the others temporarily. However, in the long run, Mew could teach the other Pokemon some new tricks.