Bloodline is a term used to describe a group of vampires who share a common lineage. While the term can be used to refer to vampires who share a sire, grandsire, or so on, it usually refers to those lineages that have some inherent distinction from the thirteen traditional clans of Caine, be it in their weaknesses, Disciplines, or both. Many of these bloodlines are, in effect, a clan within a clan.