[Editor’s note: The following contains spoilers for the “Game of Thrones” finale: Season 8, Episode 6, “The Iron Throne.”]. “Game of Thrones” was often about believing in the impossible. Accepting that heroes could return from the dead, that fire-breathing beasts could patrol the sky, that the fairy tale rhythms of old could be used for less-storybook ends. With its final stroke, “Game of Thrones” added something to that list. It delivered an ending that fit.