Vampire venom
Venom is an organic, poisonous fluid that is produced by saliva glands within a vampire's mouth. It serves five roles: as the basis for their physiology; as a mean to paralyze their prey in pain to prevent them from escaping; as a pleasant scent to lure in the vampires' human victims; as a toxin poisonous to animals and shape-shifters; and, very occasionally, as a means for vampires to procreate their species.
Riley transforming into a vampire by the venom.
When a vampire bites a human, the venom will be passed from the vampire's mouth into the person's bloodstream. If the blood contaminated with venom isn't fully sucked away, the human's heart will pump the venom throughout his or her cardiovascular system and start to infect every cell it passes within the host's body. Over the span of 2-5 days, the venom will have saturated all cells within the host, completing his or her transformation into a vampire. The process is known to be painful, described with the feeling of being burned alive.
Vampires may 'drip out' some venom from their teeth while smelling something irresistible, as shown by Jasper in Midnight Sun.
Real werewolves are the only known species to be completely immune to vampire venom, whether in the painful or transformative departments.[1]
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