What is your favorite fictional character's world? ( canon/mythology/timeline/universe )
Because a fictional character can be used in many different medium/media and each of those medium/media can be different among themselves. So a story in a storybook, comic book or video game probably won't be mentioned in the tv show of the same fictional character.
As a fictional character grows over the years, those stories can change. These changes do not make the previous stories invalid or wrong, but grow and enrich it's world.