if it would be your first, i’d recommend something simple, that you don’t need to put much thought to. for example, the backstory of of your character and what type of role it has in the story. yet, it’s hard to find something that doesn’t need much thought. the only fandom i can think of is doki doki literature club. if you don’t know what it is, it’s kind of a slow burn, but it has a good story and i don’t think much planning will have to be done if you were to choose it