Yes, there might be some out there. You can try looking on popular fanfic websites like Archive of Our Own. Just search for 'ash x diantha x cynthia' and you'll likely find a variety of stories with different themes and styles.
One common theme could be friendship. Despite the potential for romantic undertones, they might start as friends and support each other in their Pokémon - related adventures.
Another option is Wattpad. While it has a wide variety of content, you can still find some unique Ash x Cynthia fanfics. However, you might need to dig a bit deeper as there's a lot of other non - Pokemon related content too. But if you're persistent, you can come across some interesting stories.
Well, there's 'Ash and Cynthia: Unlikely Allies'. In this fanfic, they start off as strangers who gradually become friends and then something more. It's really interesting how the author develops their relationship over the course of the story. Also, 'The Power Couple: Ash and Cynthia' is a fan - favorite as it imagines them as a powerful duo in the Pokemon world.
The contrast between their characters. Ash is this energetic and somewhat naive trainer, while Cynthia is a very powerful and composed champion. Their interactions can be full of tension and charm in a romantic context.
Ash could develop his ability to understand different Pokemon cultures better. Cynthia, being from a different region, has a lot of knowledge about various Pokemon traditions. Ash could learn from her and in turn, teach her about his own experiences. This exchange could make Ash more worldly and Cynthia more in touch with the broader Pokemon community. In terms of their relationship, they could start to rely on each other more, which would be a big step for both of them character - wise.
Finding good 'ash x cynthia x diantha fanfic' might take some time. You could start by looking at Pokémon - related fanfic communities. Sometimes, fans will recommend their favorite multi - character relationship fics in those groups. It's also a good idea to check the tags and summaries carefully to make sure it's the type of story you're interested in.
You can expect unique character interactions. Ash's adventurous spirit combined with Diantha's elegance and Cynthia's wisdom could lead to interesting plotlines. Maybe they go on a Pokémon journey together or face a powerful enemy as a team.
I'm not sure specifically as I haven't read this fanfic. But it might be about Ash being taught by Cynthia in the context of the Pokémon world. Maybe she's teaching him battle strategies or some special Pokémon knowledge.
Romance is also quite common. Fans like to imagine a relationship between Ash and Cynthia, so many fics will explore their feelings for each other, how they meet cute, and how their relationship develops over time. Another theme could be mentorship. Cynthia being an experienced trainer might mentor Ash in some aspects of Pokémon training, like teaching him new battle strategies or how to better understand certain Pokémon types.