Werezompire is even better.
Frankly, I believe I saw the werepire concept executed more than a few times. The most recent one is the Vampyr video game that I already mentioned above, where werewolves are treated as an animalistic subclass of vampires.
Sava Savanovic is a serbian character. He is kind of famous because the book about him - Ninety Years Later - came out in 1880 before Bram Stoker's Dracula. He is also mentioned rather extensively in the following movie:
https://www.imdb.com/title/tt0200800/
The Butterfly is in the name because, according to several slavic myths, vampires were believed to turn into butterflies rather than bats. Though in many myths vampires are just shapeshifters altogether, with werewolves being just one of their forms.
Also, in slavic myths vampires are rarely undead and/or refined aristocrats like Dracula. More often then not they are just evil men, who are wizards and/or sold their soul to various devils. They are usually monstrous in appearance, barely resembling human.
All in all, slavic vampires is an entirely different breed from the western ones that you are used to. Much like asian vampires too. I guess, everyone heard about weird hopping chinese vampires, no?