A young wizard or witch who is trying to blend in with the Muggles could be a great addition. They could befriend Helen and teach her about the magic world in small doses. And of course, her school friends. You can show how they react to any strange behavior from Helen if she starts to notice the magic around her.
In a Helen Dursley fan fiction, you might consider a plot where she gets involved in a mystery. Perhaps there are strange happenings in her neighborhood that seem to be related to the wizarding world, but she doesn't know it at first. As she starts to investigate, she uncovers secrets about her own family's past and their connection to magic, which could be a really exciting story arc.
Obviously, Vernon Dursley could be a main character. We could explore his thoughts and feelings more deeply, especially if the fanfiction takes a different turn on his personality, like making him more sympathetic.
Kakashi could also be included. He has a history with Obito, and his relationship with Itachi was also complex. His skills and his role as a mentor - like figure can bring a different dynamic to the story. For example, he could be the one who suspects something strange is going on between Itachi and Obito and tries to figure out their motives.
Grogu is an obvious choice. You can write about his further training in the ways of the Force. Maybe he starts to show some unexpected powers that even the Mandalorian is surprised by.
Patrick could be a great addition. His simple - mindedness could contrast with Sandy and Squidward's more complex personalities. He might accidentally cause chaos while Sandy and Squidward are trying to do something important, like a science experiment or a music recital.
Obviously Beavis and Butthead themselves are essential. Their unique personalities and idiocy drive most of the stories. Also, Mr. Van Driessen can be a great addition. His attempts to educate them often lead to hilarious situations.
An old - time medicine man could also be included. He could either be a healer who tries to cure Doc Holliday's illness or a trickster who causes more problems for him. This would introduce elements of Native American culture and mysticism to the fan fiction.
Chunk is always a great character to include. His funny and sometimes clumsy nature can add a lot of humor to the story. For example, he could accidentally trigger a booby - trap while the Goonies are exploring a new cave, but then also be the one to find a way out of it in a really unexpected way.
Yasha would be a great addition. Her relationship with Beau and Jester could add an interesting dynamic. She could be the muscle when Beau and Jester get into trouble on their adventures.
In Knight Rider fan fiction, aside from the obvious Michael Knight and KITT, characters like Tanya Walker can be really interesting to include. She was a journalist who got involved in some of the adventures. Captain Darien Lambert from the 'Team Knight Rider' spinoff could also be incorporated for a different take on the Knight Rider universe. And then there's Russell Maddock, a technician who could provide some behind - the - scenes knowledge and add a bit of humor to the story.