User blog comment:A.J AL/Where does Death fit in?/@comment-26271908-20160529023830/@comment-27016424-20160529074649

They could be twins, I guess, in a sense, but such was never confirmed. Anyway, I no longer take anything passed season five as canon, so the inconsistencies lying thereafter aren't a problem for me. In 5x22 "Two Minutes to Midnight," Death claimed that he could be possibly older than God, and that might've very well been the case. However, Death might've only just been an attribute personified, like the rest of the Horsemen.