Written by Kristina
Xander: Why blood? Why Dawn's blood? I mean, why couldn't it be like a, a lymph ritual?
Spike: 'Cause it's always got to be blood.
Xander: We're not actually discussing dinner right now.
Spike: 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. Course it's her blood.
~ The Gift
Blood plays a vital role in the Buffyverse. Angel's blood restored Drusilla, Ben wondered where the blood that covered his hands was, the blood of a deer was used to resurrect Buffy, and Dawn's blood was required to open, and close, in inter-dimensional portal. But why is blood so important?
As Spike so aptly reminded Xander in the beginning of "The Gift," "blood is life." Not only does blood transport oxygen throughout our bodies, it purifies as well, as it carries away impurities. In ancient times, people believed that by drinking the blood of their enemies, they would absorb their strength. Or, like Elizabeth Bathory, bathing in the blood of the innocent would help to maintain the appearance of youth.
"It's what keeps you going. Makes you warm. Makes you hard. Makes you other than dead." Vampires require blood to stay alive… or in their case, undead. Without regular feedings, vampires become weakened, and heal less rapidly than normal, as was shown with Angel in a flashback during "Becoming Part 1." With his soul, Angel was reduced to finding blood from other sources, and in the alleys of Manhattan, he chose to feed on rats. But rats are small, and only contain a small portion of the blood that vampires require to survive. Perhaps there is more than just as physical need for the blood. As Giles mentioned in "Welcome to the Hellmouth," the first vampire was created in our reality when a retreating demon bit a human, and mixed their blood. The human became "possessed" and spread his curse by feeding on others. Every time a vampire feeds, they repeat this first vampiric act, and doom others whom they share their blood with to repeat this act as well.
As well, Dawn was created from Buffy -- from her blood. Although sisters share a blood tie, the tie between Buffy and Dawn is much stronger as Dawn IS Buffy in a sense. "No. She's not. She's more than that. She's me. The monks made her out of me," Buffy remarked in "The Gift." This was proven when Buffy stopped the flow of HER blood by jumping into the portal. Blood brings the Buffy/Dawn saga full circle, too. Dawn was born of Buffy's blood, and Buffy shed her blood, and subsequently died, to stop the world from ending. Despite knowing Dawn wasn't her true sister, Buffy couldn't help but feel a bond with her - after all, it was her blood that formed Dawn.
Blood is life. It is a constantly recurring image in "Buffy the Vampire Slayer" and "Angel: the Series". And it will continue to be as long as blood remains life. Blood is essential to the functioning of our bodies, and is the basis of mythology for the vampires in the Buffyverse. Without the transfer of blood, the first vampire would never have been created. Without the use of blood, Dawn would never have been created. Summers' blood created Dawn, and in the end, destroyed Buffy.
For more information on vampires and blood try reading Vampire Book: The Encyclopedia of the Undead. By J. Gordon Melton. Published by Visible Ink Press, 1999, USA.