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.
He might go on adventures to find different Eevee evolutions. Since Eevee can evolve into many forms like Vaporeon, Jolteon, and Flareon, Ash could search for special stones or places that trigger these evolutions. He could also enter Eevee - only competitions in the fanfiction world.
One possible fanfic could be where Ash discovers an abandoned Eevee. He decides to take it with him on his journey. Eevee quickly becomes a valuable member of his team, evolving into a Vaporeon to help him in water - based battles.
In many fanfictions, Ash achieving the status of a Pokemon Master often involves him having extraordinary battles. He might defeat powerful legendary Pokemon that no one has ever tamed before. His Pikachu could evolve into a more powerful form, which gives him an edge in battles. Also, his bond with all his Pokemon, not just Pikachu, becomes so strong that they can execute complex strategies without any communication barriers.
Well, in such a fanfiction, Ash might experience the life of a Pokemon in a very different way. He could understand their thoughts and feelings more deeply. Maybe he'd have to learn how to use Pokemon moves in his new form, which would be a really strange and exciting adventure for him.
It could be a powerful and evil Pokemon trainer who wants to capture Ash in his new Pokemon form. This trainer might be after Ash because he believes that a human - turned - Pokemon has some special power or value.
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.
His Pokemon could be his potential allies. They've been with him through thick and thin and would likely still support him even with his new vampire state. As for enemies, there might be those in the Pokemon world who fear or dislike vampires and would see Ash as a threat. Maybe some powerful and evil Pokemon trainers who want to use his new situation against him.
In Pokemon fanfiction, Eevee's bark and growl can be used to show different emotions. For example, a high - pitched bark might indicate excitement, like when it sees its trainer coming back. The growl could be a sign of it feeling threatened, perhaps when facing a wild and unfriendly Pokemon. Writers often use these vocalizations to add more depth to Eevee's character in their stories.
In Pokemon fanfiction, an Eevee pack leader could be depicted as having extraordinary leadership skills. It might lead its pack to find the best hiding places from predators or to discover the richest sources of food. For example, it could use its different evolutions' knowledge to guide the pack. An Eevee pack leader could also befriend a trainer who respects its leadership role and helps it protect its pack in a dangerous world filled with other powerful Pokemon.