The writing style can be different. French writers may have a more flowery or descriptive style compared to some English - language fanfiction. They might focus more on the emotional and psychological aspects of the characters, delving deep into their feelings and relationships. For instance, in a French fanfiction about Harry and Hermione's friendship, there could be long passages exploring their unspoken thoughts and mutual respect.
There are likely some out there. Fanfic writers often come up with all sorts of imaginative ideas. A French bunny in a Harry Potter fanfic could be used to add a touch of whimsy to the story. It might have a distinct French accent when it communicates (in the magical way that animals do in the Potter world) and be involved in adventures across the wizarding world, from the streets of Diagon Alley to the grounds of Beauxbatons Academy.
In some 'Harry Potter Knows French' fanfictions, his knowledge of French could be a part of his family heritage. Maybe his mother or a distant relative was French and passed on this knowledge. This could lead to him exploring his family's past in France and uncovering secrets related to the wizarding world there.
Well, often the French OCs are depicted as having a certain charm. They might have a more flamboyant style compared to the British characters, like wearing more stylish robes. For example, in some fanfictions, the French OCs are excellent at French cuisine - based magic, which is really unique.
One interesting 'Harry Potter family' French fanfic could be one that focuses on the Weasley family's daily life in a more detailed way, perhaps exploring how they manage with all their children during the holidays. Another could be about the Potter family's legacy and how it affects future generations in the wizarding world. There are also fanfics that might explore the relationship between Harry and his parents in a magical realm where they can interact more, like in a dream - like scenario.
The storylines often bring a fresh perspective. They can explore how the wizarding world in France interacts with the rest of the wizarding world, especially in relation to Hogwarts. There could be international magical events that involve Beauxbatons students, or they could be dealing with threats that are specific to the French magical community. Fanfic writers can also play with the idea of different magical creatures native to France and how they are incorporated into the school's curriculum and daily life.
You can try websites like Fanfiction.net or Archive of Our Own (AO3). These are large platforms that host a wide variety of fanfictions, including ones related to Harry Potter having knowledge of French. Just use their search functions to look for relevant stories.
In the fanfiction, it might be that Harry is sent on a mission to France. He then has to fully immerse himself in the French - speaking wizarding community there. He uses his French to gather information, make friends, and ultimately complete his mission, all while dealing with the differences in French magic compared to what he's used to in England.
It could be a messenger. Since bunnies are fast, a French bunny could be used to deliver important letters or small items between wizards in the fanfic.