The aggressor, dubbed the diablerist, automatically loses a point of Humanity and is branded by black streaks in their aura that may persist for several years.
Most vampires consider it a heinous act, akin to cannibalism. The act of diablerie, also called the Amaranth, involves one Cainite draining another vampire of blood and then devouring their soul. Diablerie The consumption of another Kindred's blood, to the point of Final Death.