Blood

Blood is a bodily substance found in most living creatures, including humans. Supernatural creatures such as vampires and wraiths also possess blood, which can have slightly different properties and effects.

Human Blood
In humans, blood is a substance that is essential for life. Blood carries oxygen and nutrients to different areas of the body, whilst transporting waste away. The average adult human has around ten pints. Men tend to have slightly more (between ten and eleven pints on average) compared to women (who on average have nine to ten pints). Human blood is deep red in colour. Human blood provides sustenance to vampires - it is better tasting, more satisfying and provides more strength and power than animal blood. Humans can lose around one to two pints of blood without causing serious harm, though they may feel slightly faint. Blood will eventually replenish itself if only a small amount is lost. However, losing more than two pints can be dangerous; humans who lose a lot of blood will usually have to be hospitalised and given a blood transfusion and it is possible for them to die of blood loss.

Vampire Blood
Vampire blood does not provide nutrition for vampires, but rather information, as it allows a vampire to glimpse inside another vampire's mind, seeing and sensing their thoughts, memories and emotions. Sharing blood amongst vampires is generally considered to be an intimate act and, in some circumstances, quite sensual. That being said, it can be done in a more violent manner, as demonstrated when Bianca Olivier forcibly bit Erich to see what he wanted with Raquel Vargas. The more blood a vampire consumes from another vampire, the more access they have to their mind. This works for born vampires as well as ordinary vampires. It is not known what would happen if a human drank a vampire's blood or if it would even have any effect on them at all. If a wraith drinks a vampire's blood as part of a ritual, it can temporarily give them the power to allow a male and female vampire to conceive. Mixing wraith and vampire blood can also restore a vampire's humanity, though the process is very difficult to perform correctly, with the only truly successful attempt being Bianca's resurrecting of Lucas Ross. Like human blood, vampire blood is red in colour.

Wraith Blood
Wraiths have very different blood compared to humans and vampires. It is surprising that they have blood at all, given that they are technically dead and mostly lack corporeal bodies; however, they do have blood or at least a substance similar to blood. Wraith blood is silvery in colour. Vampires usually cannot consume wraith blood, as it is poisonous to them and burns them. However, in special circumstances, mixing wraith and vampire blood can result in a vampire being resurrected as a human, or allowing a female vampire to be impregnated, which is usually impossible.

Psychic Blood
As psychics are human, their blood remains functionally the same as ordinary humans, but carries unique properties for vampires. Drinking a psychic's blood allows vampires to vividly relive human memories - either good or bad - to the point where it can seem as though they are truly there. As a result, drinking a psychic's blood can be addictive for vampires, with some vampires, such as Redgrave, enslaving psychics and selling their blood, whilst tribes have been known to go to war with each other to gain access to a psychic's blood. Other vampires will simply drain psychics of all their blood, unable to control themselves. It has been suggested, though never confirmed, that if a psychic were turned into a vampire their blood would no longer have these qualities.

Animal Blood
Animal blood serves the same purpose as human blood. Usually, they also have red blood, though their are exceptions. Vampires can live on animal blood and many choose to feed primarily on animals either out of convenience, morality or both. However, it is mentioned that animal blood is not quite as satisfying as human blood and does not grant vampires as much power. In addition, vampires cannot survive indefinitely on animal blood and must occasionally consume human blood to maintain their health.