A Lineage is a line of Prometheans who can trace their origin back through their Promethean creators to one of the Progenitors—the first Prometheans, created by human demiurges. A Lineage is primarily defined by the element used in its creation rite and the humour which the resulting Promethean has in excess.
Since the same techniques are used to create all the members of a particular Lineage, many aspects of the Promethean condition are defined by Lineage, including how Pyros may be replenished, the effects of Disquiet, and the disfigurements displayed when using supernatural abilities. Each Lineage also grants certain advantages called Bestowments, including such things as superhuman strength and stamina.
Lineages are named for a prominent figure in their history, usually their demiurge or Progenitor, though each also has various nicknames. There are only five known Lineages, and most are very old: the Tammuz and Osirans date back many thousands of years, and the Ulgan and Galateids both predate Christ. Frankenstein, the most famous Lineage—among modern mortals, at least—is a very recent addition.
A sixth Lineage has supposedly appeared in the last few decades, born not from a natural element but from the power of the atom. Sighting of "Nuclear Prometheans" are considered little more than legends, but the fact is the Zeka do exist. However, because of their dangerous natures and methods of creation, they tend to remain extremely reclusive, content to exist in secret.