Many scholars, vampirologists, and vampire hunters alike believe that vampirism is a kind of "supernatural disease", for which there is no known cure. It has been long theorized that the vampire's bite deposits a kind of enzyme found in the vampire’s saliva into the bloodstream of its victim.

If the vampire draws too much blood to cause its victim to expire, the enzyme triggers a metabolic change in the victim's body, beginning with the production of a strange dark-green liquid called "ichor" within the victim's bloodstream. In about three days, there is enough ichor to nourish the victim's body the way that blood once did. If the "host-vampire" is not properly destroyed within this three-day period, the victim will return to "life" as a vampire.

If the victim's blood loss is not significant enough to cause death, the victim will show signs of progressed anemia due to the effects of the enzyme in his/her bloodstream, but will not die. Until the enzyme has fully metabolized, the victim will be weak and sickly -as well as being susceptible to the hypnotic commands (whether conveyed verbally or telepathically) by the vampire that attacked him/her.

The victim will almost always develop a perverse, often amorous attraction toward the vampire that bit him/her as well. The victim may be spared the horrible fate of becoming a vampire (and returning to normal) if the host-vampire is properly destroyed before the enzyme metabolizes itself -claiming the victim as a vampire. Likewise, should the victim suffer more attacks from the vampire-host during this time, the metabolizing process will be expedited, causing the victim to "turn" at a much quicker rate.