Inseparable

The things you thought you knew about vampires and demons are nothing like this. Try to imagine how these 2 great and powerful breeds become bitter enemies. Would they kill each other in cold blood in order to end this never ending feud or will they be able to bring their families together again?

A young princess has been living in a palace and taught that demons will kill in cold blood but what would happen if she meets their abandoned living heir?
Would he kill her as she has been told or will they start something that could end the never ending war between their kinds forever?