The Vampires of lore are described as very old people who suck the blood of youngsters to stay alive. The parts about them fearing sunlight, or garlic, or whatever, might just be based on side-effects of this cure for ageing. The inaccuracy of "sucking" instead of transfusion, might be because nobody survived to recount the exact way in which vampires took their blood and what they did with it. All they knew was that bodies of young people would sometimes be found, drained of blood and with tiny syringe-like marks on their necks.
In fact, they might still be among us, ruling our world from the shadows :-)