I hate summaries...Lelouch and Suzaku meet as children. They are engaged to create an alliance between Britannia and Japan. They are other reasons why it's between two males and not a "traditional marriage" (if that is what you call a marriage between opposite genders.) I talk about it later.. the plot is not the only reason. At first Suzaku agrees Lelouch is beautiful, but isn't confident about being engaged to a boy and Lelouch sees it more so like a mission and never thought he'd find himself in love. Eventually they blossom into a beautiful flower. (You choose the flower.)