The ker is an eidolon [image], or winged sprite, which wears a sinister aspect - it is an object of fear. If it is angry and seeks vengeance, it is an Erinyes. Considered as allotted to the individual at his birth, it is his moira - the span or limit of his vital force, the negative and repressive aspect of his fate.
Greene defines ker as the individually allotted, sinister aspect of personal fate — an eidolon that collapses into moira and, when vengeful, into the Erinyes, distinguishing it from the beneficent daimon.
, The Astrology of Fate, 1984thesis