“Game of Thrones” Season 6, episode 9, “Battle of the Bastards,” had its fair share of casualties. Because “Game of Thrones” is fiction, fans can feel cheated with an unsatisfactory conclusion or an ending that feels unwarranted. That’s why the fate of Rickon Stark feels like a wasted opportunity when “A Song of Ice and Fire” seemed to be setting the youngest Stark up for something important.