A possible fanfiction plot could be that Ash, Serena, and May are invited to a mysterious island full of unknown Pokemon. They have to work together to survive and discover the secrets of the island. Ash's leadership, Serena's ability to communicate with Pokemon, and May's quick decision - making skills would be crucial.
One idea could be a story where Ash, Serena and May team up for a special Pokémon tournament. They each bring their unique skills and Pokémon to the competition. Along the way, they face challenges that test their friendship and teamwork. For example, they might have to deal with a devious trainer who tries to sabotage them.
In some fanfictions, Ash might develop a special bond with both Serena and May. For example, they could be exploring a new region together and encounter a rare Pokemon. Serena could use her knowledge of Pokemon behavior to track it, May could come up with a battle plan, and Ash would be the one to catch it. This kind of adventure would strengthen their friendship and show how well they work together.
One common theme is friendship. They often go on adventures together, and the fanfictions show how their friendship develops. Another theme is Pokémon training. They share their experiences and learn from each other about training different Pokémon.
Misty had a feisty relationship with Ash. They were like two kids always bickering but having a deep bond. May's relationship was more about shared goals in the Contest world and learning from each other. Dawn was similar to May in the Contest aspect, but her friendship with Ash seemed more innocent and supportive. Serena, she had a relationship with Ash that had a touch of romance. She was inspired by him and as they traveled together, her feelings grew. Each relationship is unique and offers different possibilities for fanfiction writers to explore.
Well, it really depends on different aspects. Misty was one of the first to be with Ash and they had that classic bickering relationship that was really cute. May brought a whole new dynamic with her Contest journey and her growth with Ash was more about mutual learning in that regard. Dawn also had her Contest focus and her relationship with Ash was full of support and friendship. Serena, on the other hand, had a more romantic undertone to her relationship with Ash. So, there's no definitive 'best'. It varies from person to person based on what they like about each character's relationship with Ash.
One common theme could be friendship. Since Ash, May, Serena, and Lemon are all characters, their relationships can be explored in terms of how they become friends and support each other.
A great plot twist could be that one of their Pokémon turns out to be a legendary in disguise. For example, Serena's Fennekin could be revealed as a Zoroark that was sent to protect her, but she had no idea all along. This would completely change the dynamic of their journey.
Another place to look is Archive of Our Own (AO3). There are often creative takes on the relationships between Ash, May, and Serena. For example, some fanfictions might explore their friendship growing deeper over time as they each pursue their own Pokémon - training dreams. It could be about how they support each other through tough battles and difficult decisions.
I think Serena is more popular in Ash fanfiction. Her character development in the anime was quite significant, especially in relation to Ash. In fanfictions, this can be taken further. Her determination to follow Ash and her own dreams simultaneously makes for great story material. While May was a great character, Serena's more recent and somewhat more complex relationship with Ash gives fanfiction writers more to work with, like exploring how they might reunite or continue their journey together in different scenarios.