Obviously, Harry Potter himself. Given his heroic nature, he would likely be the first to approach Jessica Rabbit if she were in trouble or if she was causing some sort of stir in the wizarding world. He would be curious about her and her very different appearance compared to the wizards and witches.
Well - developed characters. A great fanfic would really dig into the personalities of Roger and Jessica. It should show their relationship in a new light, perhaps exploring their backstories more deeply or showing how they interact in different situations than in the original movie.
You can start by looking at fanfiction websites like Archive of Our Own. There are often a lot of fan-created stories about Roger Rabbit and Jessica Rabbit there. Just search for their names in the search bar, and you'll be presented with various fanfics to choose from.
Some fan fictions focus on Jessica Rabbit in a different genre, like a science - fiction setting. Picture her in a world where toons co - exist with advanced alien races, and she has to use her unique abilities to navigate this new and strange universe.
She could be a mysterious visitor. For example, she might appear in Konoha and immediately draw the attention of all the villagers with her unique appearance. Some might be suspicious of her, while others, like Naruto, would be curious and want to befriend her.
One common theme is the allure of Jessica Rabbit. Since she's such a iconic and attractive character, fics often play on that, with the reader being drawn to her charm. For example, in many stories, the reader might first see Jessica Rabbit on stage and be instantly captivated.
One idea could be that Jessica Rabbit somehow gets lost in the wizarding world of Harry Potter. Maybe she's on the run from some toons who are after her and stumbles through a magical portal into Hogwarts. The students are all amazed by her appearance, and she has to figure out how to get back home while also dealing with the strange new magic around her.
One way could be through a crossover spell or a magical portal. Imagine Naruto accidentally stumbling through a portal into the world where Jessica Rabbit exists. His ninja skills would be quite out of place there, but his determination and ability to adapt could lead to some interesting adventures. He might have to use his shadow clone jutsu to deal with the various situations in this new and strange world filled with toons.
You can start by looking on fan - fiction websites such as Archive of Our Own (AO3). It has a large collection of fan - created works, and you're likely to find a variety of Jessica Rabbit fan fictions there.