Definitely not. Paranorman is a work of fiction. It's a product of creative minds coming up with a unique and imaginative tale, not drawn from any true events or people.
One common theme is the exploration of Norman's powers. Fanfictions often expand on how he can interact with the spirit world and what new things he can do. Another theme is friendship. Since Norman is a bit of an outcast, many fanfictions focus on him making new friends, either among the living or the dead. Also, mystery is a big theme. The idea of solving supernatural mysteries in the town is quite popular.
One common theme could be the exploration of unrequited love, just like in many other fanfic. The characters in 'Paranorman' might be put in situations where they have feelings for someone but are afraid to express them due to the nature of their relationship or the circumstances around them.
Sure. One popular Paranorman fanfiction is 'The New Adventures of Paranorman'. It continues the story after the movie events, with Norman facing new supernatural challenges in his town. Another one might be 'Paranorman's Secret Allies' which delves into the idea of Norman making some unexpected friends in the spirit world. There's also 'Paranorman: The Next Chapter' that imagines what would happen if Norman had to pass on his gift to someone else.
Maybe a powerful demon that has been lurking in the shadows of both universes. This demon is attracted by the unique magic in both Coraline's and Norman's worlds. It starts to possess the people and creatures in both places, and Coraline and Norman must find a way to exorcise it. The demon could be very cunning, disguising itself as friendly beings at first.
I'm not sure who Mitch Campbell is without more context. There could be many people named Mitch Campbell. Maybe he's a character created specifically for this story.
Once upon a time, there was a little girl named Lily. She lived in a small village surrounded by beautiful forests. One day, while exploring the forest, she found a hidden path. Curious, she followed it and came across a magical pond. The water in the pond was glittering like diamonds. There was a tiny fairy sitting on a lily pad. The fairy told Lily that she could make one wish. Lily wished for her village to always have enough food. And from that day on, the village had bountiful harvests every year.
I'm sorry, I'm not aware of specific 'Paranorman' gay fanfic to recommend. You could try searching on some popular fanfic websites like Archive of Our Own, where there might be some works related to it.
A plot could involve Coraline getting lost in Norman's town and Norman has to help her find her way back home. Along the way, they discover that there are some common elements in the spooky things happening in both their places. For example, the same kind of magic or curse is at work, and they use their unique skills to figure it out. Norman with his ability to see ghosts and Coraline with her courage and inquisitive nature.