I don’t consider Coates’ version of Black Panther to be fanfiction. Marvel Comics hired Coates’ to write for the brand. Even though he is and has been a fan of Marvel comics for years, he was both an employee and fan when writing the Black Panther. Marvel Comics still owns the IP rights for Coates’ work, therefore it is not an independently created work. Nor does Coates’ story offer commentary on preexisting Black Panther comics. It is an original work created under brand ownership. It is not fanfiction.