You are is a royal (whether king/ queen,prince/princess), you are expected to have an heir soon. But you have a problem-youre unmarried and in need of a spouse. Though you host masquerades and balls you find no one ideal for a king/queen. Until you hear of (insert Character of your chooseing). They make a deal with (insert Character) that if they help them have an heir they will ally with them- which by the way- your kingdom is quite well known and has conquered and allied with the most kingdoms.