Vampires

Vampires are magically reanimated human corpses which are inhabited by the spirits of the deceased person and who closely resemble the living human they were before their transformation. Vampires feed and survive on the blood of the living, typically on that of humans, and they can also transform other humans into more of their kind.

Creation
A human who has consumed vampire blood and has subsequently died with the blood in their system will be magically revived as an undead vampire, just like the vampire who sired them. The exact nature of the human's death is irrelevant to this process; the only condition that must be met is that the body has to be more-or-less intact and able to function once they reawaken in transition. In order to complete the transition into a vampire, the person must then consume a significant amount of human blood, at least a sip's worth, within the next twenty-four hours, or else they will die. Vampires can only feed on human blood to complete their transition. Until a vampire drinks human blood to complete their transition, they will be not be susceptible to the standard weaknesses of the species they are soon to become (i.e. they can still walk in sunlight and can enter homes without an invitation)

Physiology
Vampires' diet consists mainly of blood, human, animal or vampire. Blood (especially human blood) does not only satisfy a vampire’s thirst, but it also heightens their supernatural abilities, making them stronger, faster, and able to heal much more quickly than they would after not eating for a significant period of time. The longer a vampire abstains from blood, the more likely the vampire will becoming feral and unable to resist feeding on whomever they come upon. In many cases, a vampire who has been starved for a long period and is risking desiccation will eventually become so overwhelmed with hunger that the lose all sense of their humanity and rationality altogether and finally give into their bloodlust. It has been demonstrated that vampire blood, just as with human and animal blood, can be used to revive a vampire who has been desiccated (even if they ordinarily do not partake in the consumption of vampire blood), and it can also help a badly injured vampire heal more quickly if human or animal blood is not available. However, human blood is most compatible with a vampire's dietary needs, and because of this, the majority of vampires rely on it as their sole food source.