Properties of the Blood

More than anything else, blood defines the Kindred. Within seconds after a vampire consumes blood, the vital fluid changes into something quite different that the Kindred call Vitae. Vampire Vitae looks like mortal blood, but it doesn’t flow like mortal blood. A vampire’s Vitae moves through her body at the behest of the character’s will, not because of a beating heart. Kindred don’t bleed when they are wounded; Vitae might pool slightly in the wound, but it does not flow forth unless the vampire wills it to do so.
Vitae retains its supernatural properties for a few minutes after it leaves a vampire’s body and is exposed to air, and then reverts to ordinary blood. A scientist who examines a sample of former Vitae would find a mixture of blood from many sources, with some of the cells broken down. Some Theban Sorcery practitioners know procedures to preserve the supernatural power of Vitae outside a vampire’s body, and blood that came from a vampire always retains a mystical connection that ritualists can exploit.
Kindred employ their Vitae for many purposes. As a vampire calls upon the occult power in her stolen blood, the actual mass and volume of Vitae in her body decreases. As a character uses up her Vitae, her skin tightens and blanches and her body shrinks slightly. She looks less alive. Feeding enables her to restore her lifelike appearance — as lifelike as the character can manage, anyway.
A player may spend Vitae in the same turn in which he spends a point of Willpower. Spending a Vitae is always a reflexive action. Even if the actions that doing so enable might not always be reflexive themselves (such as with certain Disciplines), the act of spending the Vitae is.