Eric didn't ask to be a vampire. In fact he didn't even believe in them. Biting your own tongue with your fangs does a lot of convincing. Even so, being a part-time undead isn't as easy as you might think. It can let you hold down a day job, true, but sometimes the night "life" can be more than a little difficult, what with those bloodthirsty urges and predatory instincts kicking in.
"Ahh no fair no fair"
It's not easy being king. Especially when you've got an allergy to sunrise and sunset, a fire goddess for a mother-in-law, demonic adversaries, random assassins, and a basement full of insecurities to cope with. Add to that his daughter, the fire priestess/princess; a couple of lightly deranged professional magicians; a whole city full of wizards; and enough squabbling princes to resemble a kindergarten argument. It's enough to make a man want to just go home.
We all have inner demons. We fight them all the time. Some of us achieve inner peace by coming to terms with them. But how do you come to terms with inner demons that tear free and become outer demons? Eric has been a vampire for nearly a century, and his demons are more than metaphors. While they controlled him, he was the Demon King. Now he has to avoid the monsters in his own mind, as well as angry nobles, fanatical religions, assassins, magi, other vampires, criminal organizations, and more.