I'm pretty sure there were many instances where it was made obvious that Sienna should kinda butter up to Nya and marry him, BUT he has also called the emperor of the western empire "uncle". That would mean that Nya and Sienna would be cousins... I know that this was common in such times because the families did not want other blood mixing with their pure family's one but all I can say is SWEET HOME ALABAMA
Am I the only one who's curious as to what happened to the magician at the end?