Vampirism as a theme can be fabricated in many ways. One does not literally need to drink blood to be a 'vampire' as far as narrative elements and style goes. A vampire is ultimately a predator who preys on his or her own kind, so any idea you can formulate within the lore for needing to prey on others can feed into a vampire style of character. You could consume their energy, or aether, or souls, or minds, or whatever.Â
Traditional vampires do not exist, but unless you're super-attached to that very specific element, there are work-arounds.Â
In particular, I don't think the voidsent are too heavily understood. Lots of voidsent exist, but we don't know the full extent of what they are capable of. A 'vampire' in the context of FF14, could be as simple as a power-hungry individual who has made a Faustian deal with a powerful voidsent, and has gained some kind of power, but must now 'feed' on others to sustain it or sustain themselves.
Traditional vampires do not exist, but unless you're super-attached to that very specific element, there are work-arounds.Â
In particular, I don't think the voidsent are too heavily understood. Lots of voidsent exist, but we don't know the full extent of what they are capable of. A 'vampire' in the context of FF14, could be as simple as a power-hungry individual who has made a Faustian deal with a powerful voidsent, and has gained some kind of power, but must now 'feed' on others to sustain it or sustain themselves.