Perhaps an OC who is a young child with an uncanny ability to sense danger before it arrives. This could add an interesting dynamic to the group as they try to protect the child while also relying on the child's special ability to avoid walker herds and other threats.
There's also 'The Unseen Heroes' which is a fanfiction that explores the stories of the background characters in 'Fear the Walking Dead'. It's fascinating as it shows how these often - overlooked characters can have important roles in the overall apocalyptic world of the show.
Fear the walking Dead does have its roots in a comic. The comic provides the framework and inspiration for the TV show, with some creative adaptations made for the screen.