You can start by looking on fanfiction websites like Archive of Our Own. It has a large collection of fan - made stories from various fandoms, and there's a good chance you'll find some villager x isabelle fanfiction there.
One popular villager x isabelle fanfiction might be those that focus on their friendship. For example, a story could be about how they work together to organize a village event. They could be planning a flower festival, with villager using their unique skills like fishing to contribute to the decorations, while Isabelle takes care of the administrative tasks and announcements.
One plot idea could be that Isabelle and the villager team up to organize a huge festival in the village. They face various challenges like getting enough resources and convincing all the villagers to participate. Another could be a story where the villager gets lost in a mysterious part of the island and Isabelle goes on a quest to find them. It could also be about them working together to beautify the village and during the process, they discover a long - forgotten secret about the place.
To develop Isabelle's character, focus on her organizational skills. Show her making detailed plans for village events. For the villager, emphasize their relationship with the other villagers. Maybe they are the one everyone goes to for advice on gardening. You can also show their reactions to different situations. Isabelle might be calm under pressure, while the villager could be more impulsive.
A fanfic like this could be really interesting. Maybe it delves into the backstories of both Fe Chrom and the villager maiden. It might show how their paths cross and how they interact with each other. It could also add new elements to the existing lore of the Fe universe, like perhaps a new magical ability that the maiden has that helps Chrom in battle.
Common themes in Sabel x Villager fanfic can be quite diverse. Besides friendship and romance, there could be themes related to community. Maybe they work together to improve their village or help the people in it. Another possible theme is mystery. They could be involved in solving a mystery that plagues their village or a nearby area. There might also be themes of sacrifice, where one of them has to sacrifice something for the other or for the greater good of their community. These themes often add depth and interest to the fanfic stories.
The relationship could develop through shared dreams. Isabelle and the human start having the same strange dreams every night. At first, they are confused, but as they start to communicate about these dreams, they find a deep connection. This unique way of communication could be the starting point of a very special relationship.
A common trope is the 'enemies to lovers' or at least 'rivals to lovers'. Since they have different personalities and ways of doing things in the Shadowhunter world, it can be interesting to see how they overcome their differences. Another is the 'hurt/comfort' trope, where one of them gets injured or is in a difficult situation and the other provides support and care.
There could be a lot of character development. For example, the maiden might start as a shy and simple villager but grow into a strong and important figure with the help of Chrom. And Chrom might also change, becoming more empathetic perhaps due to his interactions with the maiden. The fanfic may also include details about the world they live in, like the local customs of the village that the maiden comes from.
Romance is also quite prevalent. Writers might explore the relationship between Isabelle and the wolf, how they fall in love, overcome differences, and build a relationship. There could be cute moments of flirting and getting to know each other.