Fan Casting Canon Foreigner in Sort by Tropes

When an established existing medium ventures into the Expanded Universe, writers will often rely heavily on familiar characters and past storylines from the official canon to ensure that fans of the original material are happy. Unlike the original canon, however, an "expanded universe" adaptation also gives the writers freedom to introduce new, "never before seen" characters, as the production staff enjoys their newfound liberation from whatever codes and limitations ruled the original work.