J.C. mentioned that he was reading a Vampire sourcebook while watching Game of Thrones. Game-deprived as I am, I replied with the following:
Or you could just rip-off the plot, whole hog. Your buddy is prince and needs you to take a job in the city that does not suit you. You live in the country with the werewolves in relative peace. The vampire clan you deposed has a lost bloodline in exile somewhere. In order to secure the princedom, you had to bond your friend to a vicious clan in order to secure your power-base and they have taken over his court.