First, they didn’t call them vampires. They were either called moroi, which comes from the Romanian word “mort” meaning “dead” or the Slavic word meaning “nightmare,” or they were called strigoi, which apparently come in both live and dead versions.
Living strigoi were more like witches. They had two hearts, or two souls or both. At night they would send out their souls to visit with other strigoi and, on occasions snack on local livestock and neighbors.
Dead strigoi were reanimated corpses that consumed blood and attacked members of their living family.
Interestingly enough, you could be born with an predilection for becoming a vampire in Romanian lore. If someone was born with a caul, an extra nipple, a tail, or extra hair — no doubt about it, he or she was doomed to vampirism. And, watch out families with lots of children. If the first six were the same gender, the seventh child of the same gender would become a vampire. And poor preemies — they were also doomed.