Blood Exchange refers to the mutual sharing of vampire and human blood (each drinking from the other) in "The Southern Vampire Mysteries". Blood exchange can either lead to the creation of what is known as a "blood bond" between a vampire and human (if done on at least three separate occasions or in rare occasions less than three) or the siring of a new vampire (if the human dies and has his or her fluids replaced by vampire blood).
A "blood bond" links the pair empathically, enabling them to feel each other's emotions and causing them to feel safe and secure when in close proximity to one another. This empathic connection can also make it harder for the human and vampire to distinguish real emotions (such as love and hate) for one other as opposed to the artificial ones created by the blood bond. A blood bond also increases the physical attributes of the human, including but not limited to strength, speed, healing and beauty. Humans involved in a blood blond are much stronger than they would be naturally, but are not as strong as vampires. Blood bonds are also precarious because they can lead to the unintended siring of the human into a vampire. If a human in a blood bond either dies or is seriously injured and then imbibes the blood of his or her vampire partner the human may become a vampire. Blood bonds can also be disorienting to humans if they are in the presence of multiple "relatives" of their vampire partners. This is because vampire relatives share blood lineages and it causes the humans to be bombarded with the emotions of multiple vampires concurrently.
Vampire blood without exchange is sought after by humans as a drug that can enhance strength, heal wounds, and increase attractiveness, among other effects.