If we were to have an actual vampire... (Vladimir and Evelynn don't count)
League lacks an actual Vampire Champion, with Vladimir and Evelynn being "close, but not quite there". Vladimir never bites people to suck out their blood (and doesn't drink it, AFAIK), and not even Riot knows what the hell Eve is supposed to be.
If Riot were to make an actual vampire, how do you think they should go about it?
already fill the Niche, Unless you deliver the same fantasy in a new way.