A master vampire can bring someone over with little risk, as can a normal vampire with a master helping out, but a lone non-master vampire attempting the process often creates an undead psychopathic homicidal monster instead of a peer. Such a rogue vampire is often called a 'Revenant', roaming the night and tearing into anything animate, leaving corpses and perhaps more Revenants in its wake. This situation also rarely can happen in a normal bringing over of someone in a manner not unlike a birth defect, and is called "Vlad's Syndrome". Like any other impassioned vampire, the eyes of Revenants contract down to seem like they have no pupil in the center. Unlike impassioned vampires though, they do not glow when caught up in emotion.
Revenants generally have a three-way emotional switch: Feed, Kill, Rest. It toggles between the first and the last depending on if the sun is down or up, the middle setting only kicking in if either plan is ruined. Too much Power than Willpower can begin to lead to Revenancy, as can not feeding for an extended amount of time (months, if not years). When brought about by hunger, it is often "fixed" by feeding. Standard Revenancy is incurable though, and as such no Revenant PCs are available as character concepts (although it may happen post-CharGen if one wants their vampire character to go out with a bang, or if misfortune befalls them).
Some researchers theorize that Revenants are the only "true" vampires, while the more well-behaved vampires are merely staving off the inevitable. In the far East, Revenants who are in possession of some of their preternatural vampiric abilities (Flight, Control Shape, et cetera) are the origin of the raksasha myth.