Vitae

In it's most basic sense, vitae is a term vampires use to refer to blood. More specifically, it is the source of a vampire's unlife and powers. The "blood" in a vampire's body is more than the admixture of plasma, platelets, hormones and whatnot which courses through the veins of mortals. When blood enters a vampire's body it is mystically transformed into vitae, giving it the power to form blood bonds, create childer, and infusing it with a power that is attractive to mages.
Furthermore, vitae is almost always more "condensed", meaning that while vampires have the same amount of blood in their systems, they possess more blood points. In VtM the maximum amount of vitae a vampire can have at any given time is determined by their Generation, as described on p 139 of the Vampire: The Masquerade Revised Edition. In VtR the maximum amount of vitae is determined by their Blood Potency, as described on p 99 of the Vampire: The Requiem Rulebook.
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