I don’t mean legally. I just mean morally.
Here’s the backstory; The video game developer CDProjektRed, made a very popular series of games based off of a very popular fantasy novel, The Witcher.
In The Witcher, these superpowered monster hunters are known to be trained at three different schools. School of The Wolf, School of the Cat, and School of the Griffin.
The games later added four more schools that are not official book canon. The Schools of Viper, Crane, Bear, and Manticore. The writers who wrote this certainly got paid, but of course not nearly as much as the original book author.
After the popularity of the franchise, a fandom was formed, and fan fiction writers developed