Look at this.
It’s called a fan fiction. Fanfic or fic for short.
Not entirely legal due to copyright reasons but has been around since forever. It’s when a fan writes fiction based on something that isn’t theirs (TV show, book, movie, etc) and uses someone else’s characters. Can’t be sold for profit and written for fun. They can be found on fanfiction.net, Ao3, wattpad and other sites. People normally don’t mind others playing in their sandbox and turn a blind eye to it. People who do mind say so and then people delete what they’ve posted and stop writing more.
There’s bad fan fiction and good fan fiction. There are ratings (stay away from M), filters (use to find the good stuff based on reviews/kudos/views), categories (gen, F/M, M/M), warnings (minor character death) and other stuff.
I gave you a link to an amazing one. Go ahead and read it. Being made into a web series on youtube because it really is that good.
“You may be the most interesting person I’ve ever met.”
“We haven’t met.”
“A minor detail.”
All dialogue AU in which John sends a text to the wrong number by mistake. Little does he know the person he just texted will impact his life more than he could have imagined.
A video about the webseries: