I think that there isn't really much of a fanbase to put vampires of any sort in this game. Nitara will be accepted because she had a small role to play in the past and because she has distinctive moves based upon her species. A samurai vampire, maybe, could be interesting if, and only if, (s)he was made to be very different from Nitara both in terms of moves and appearance. I don't think you'll convince many people on this site that any other vampire characters would be a good addition. Except maybe bringing back Kahil Grigesh or whatever his name was - the vampire holder of the Kriss mentioned in Nitara's Armageddon ending. He might possibly be an interesting vampire addition. Possibly.
Try thinking more in terms of Eastern mythology or take inspiration from other fighting games if you want to keep suggesting new characters. And please, don't just take something and add the word 'vampire' in front of it!
C-Sword, I wish I could Thank you for that post over and over again