Ever wondered why there is a mention of vampires in almost all cultures ? Mythology with multiple accounts usually points towards truth. But, how come humans with all their technology are unable to provide any evidence towards their existence ? That is because humans are mortal with limited accounts, and their is someone higher up that governs the vampires, that keeps their existence hidden. Someone, a group of kings and queens that set the rules for the vampires, and they might have made peace with humans before, but they want their home back. They want Solenstown back, and they are not going to let anyone stand in their way.
Just think of this 'fictional' possibility, starting with a group that never ages, has access to infinite time and powers to control anyone. To what extent will they go to keep their identities hidden, make their victims disappear and control their habitat. Imagine if someone does exist with these endless powers, would you ever even know who they are.