Fan-Watching Is a Fan-Fiction Thing, If It Has an Original Protagonist! ! !

I want to read a book similar to "(Mainnet King) The Uncrossable Line". It's the kind of book that is a second creation by a fan, and then a fan or a fan of the original work watching the movie. It can be a standalone book or, well, it's okay to have extras in a book and watch the movie, but it must be