I'm going to echo everyone else who is dissapointed they only get 1. They really need two so unless Jason can be in two places at once one of them, most likely the boy, is going to be left without a guardian. I really don't like when fiction treats twins like they are one person. In this context it makes less sense. Even if they never get married, society will naturally separate Arjen and Arien based on their gender and then what?