Blackbloods

In Atlantis there are the so-called Blackbloods. Atlantean families are divided into Redbloods, Bluebloods, Yellowbloods, and Greenbloods, depending on who you were descended from. These are all relatively equal, however, even the Redbloods descended from the Gods - the Blackbloods, however, are below all of them.
In the early years of Atlantis, when the Gods were still alive, the young state was often beset by enemies, many of whom were defeated eventually. Once conquered, the common people of these states were usually assimilated into Atlantis easily enough; however, the ruling classes were distrusted for obvious reasons, especially after many of them often rose in rebellion. Their descendants became the Blackbloods, a living reminder of the villains who opposed the Gods. Though the Gods did not approve of this, people were already discriminating against the Blackbloods by the time the last God died in 88 AY. By the late 100s AY, there were official governmental and religious policies that enforced this discrimination. Blackbloods often got crappy jobs or had to turn to crime, and lived in slums throughout the Atlantean Empire, a far cry from their upper-class origins. Some religious fanatics believed even being near one would corrupt one's soul. Also, though, Atlantis technically had universal suffrage, the Blackbloods were not allowed to vote out of tradition (think Jim Crow) and had no representation in government.
In the Kingdom of Mason, a heretical rebel state that split from Atlantis in 300 AY, the Blackbloods were treated even worse, and became slaves to the state in all but name. There, the concept of Blackbloods was extended where the government could assign Blackblood status to anyone, their family and descendants as a form of punishment - at least in Atlantis, in theory, Blackblood status could only be conferred if there was proof that your ancestor was one of those people who opposed the Gods.
Note that not every leader who opposed Atlantis was considered Blackblood. Only those who fought against Atlantis in its early years, when the Gods were still alive, and were believed to be actively against the Gods in popular perception, were considered Blackblood. For instance, the descendants of the Exeran general who ambushed and killed the God Gregory Wei, are Blackbloods; the descendants of his subordinate commanders, who were said to have advised him against it, are not. In fact, there is one Blackblood family who are descended from a God - the descendants of Robert "Bob" McEire, who tried betraying his fellow Atlanteans to their enemies and attempted to bring about the second Collapse. Occasionally, the Blackbloods are called the Sons/Daughters of McEire because of the association with him.