- "Blood is life, lackbrain. Why do you think we eat it? It's what keeps you going, makes you warm, makes you hard, makes you other than dead."
- ―Spike to Xander Harris on the nature of blood.[src]
Blood was a specialized bodily fluid that delivered necessary substances to a body's cells – such as nutrients and oxygen – and transported waste products away from those same cells. It was found in most beings, including humans.
- Vampires were well known to feed on the blood of mammals.
- In order to make a new vampire, the sire would have to drink a large amount of the victim's blood before letting the victim drink some of theirs.
- The Archduke Sebassis kept a slave of the same species whose blood was regularly extracted from his body and made into a refreshment for his master.
- The consumption of blood could provide details about the person. Glorificus instantly determined that Tara Maclay wasn't the Key by licking her bloody hand and Spike confirmed that Cordelia Chase wasn't a demon after drinking some of her blood.
- Mohra demon blood possessed potent healing properties and was even able to revert a vampire back into a human.
- The blood of the Slayer was the only known cure for the Killer of the Dead, a poison specifically designed to kill vampires.
- The blood of a specific type of telepath demon could grant telepathic abilities to whoever made contact with it.
- Slayer's blood could strengthen vampires. This was most evident when the Master used Buffy's blood to break free from his prison.
- The power of the Senior Partners was granted to Marcus Hamilton within his blood. Drinking his blood granted the consumer with his power.
- Blood from prophetic demons, when consumed, could give vampires visions.
Uses in magic
- Blood was a central ingredient in resurrection spells.
- Angel/Angelus' blood was the key ingredient in the ritual of awaken Acathla as only Angel's blood-soaked hand could remove the sword from Acathla's body. Likewise, his blood was needed to stain the blade of the sword used to deactivate Acathla.
- As the human form of The Key, Dawn Summers' blood possessed the power to tear down the barriers between Earth and other dimensions when used in the proper ritual. Since Buffy shared the same blood as her, she was able to close barriers.
- An unidentified shaman needed Darla's blood in order to identify her unborn child by mixing the blood with other ingredients and touching her stomach with the blood on his hands.
- Blood was needed to open the Seal of Danzalthar.
- The blood of any demon was required to open a portal to Beljoxa's Eye dimension.
- The Cloaking Dissolution Spell required arterial demon blood.
- The Sisterhood of Jaro Hull drank Connor's blood as part of a ritual to enhance their strength.
- Flesh Magic
- Spilling blood on the Mark of Gachnar would summon the fear demon Gachnar.
- According to Spike, blood smelled metallic, similar to a penny.
- According to Spike, demon's blood tasted astringent and oaky.
- Slayer's blood apparently was a great aphrodisiac.
- Eating the Doublemeat medley made the consumer's blood undesirable to vampires.
- Drinking blood could free the consumer from forms of mind control.
While the majority of beings had red blood, blood could come in various colors depending on species.
- Green: Mohra Demon, Fyarl Demon, Spawn of Sobek, Durslar Beast, Baby-killer Demon, Vampy Cat, Plagiarus Demon
- Yellow: Skilosh Demon, Kungai Demon, Wig Lady, Parasite Demon, Root Monster, Suvolte Demon, Spike's crew
Behind the Scenes
In the 2002 non-canonical Buffy video game, a pair of vampires were seen discussing whether they should eat out at a drive-through because one of the vampires claimed that the blood of fast-food clerks tasted delicious, while the other vampire considered them too greasy because their high cholesterol gave him gas as a result.