Whispers in the dark
Pinpointing precisely when the first Slave to Darkness was born is difficult to achieve. Since the dawn of time within the mortal realms the Chaos Gods’ tendrils would reach through and warp reality, whispering dark thoughts to anyone who would listen. Khorne would urge Generals to strive for evermore glory, Tzeentch would encourage further study into the arcane, Slaanesh would speak of pleasure to aristocrats and artists alike, and father Nurgle would call out to those who lived off the land. It is when the first of these individuals gave in to the dark voices which lurked within and pledged themselves to these mysterious forces that the first Slave to Darkness came into the Mortal Realms.
A crippling defeat
Sigmar and his Pantheon were the all-powerful Gods who sought to shepherd all the races within the mortal realms. Aware of the existence of Chaos, they prepared for the eventual day that the Ruinous Powers would invade the mortal realms. As the age of Chaos began, the daemons poured in, slaughtering all who did not join them. At the battle of the Burning Skies Sigmar was betrayed by Nagash, and in turn was decisively defeated, retreating into Azyr. Those few who remained would either be forced to concede and accept the Chaos gods as their own or be slaughtered in the wake of their victory.
The Great Game
Tzeentch, Nurgle, Khorne, Slaanesh, and the Great Horned Rat though allied against Sigmar and the forces of order, are only allies of convenience when it suits them best. Otherwise, they forever compete within The Great Game, in which each god seeks to dominate the others within the realm of Chaos. This Game of course extends well within the mortal realms, where they constantly vie for control of land, resources, and followers.
Archaon the Everchosen
Perhaps the greatest encapsulation of the Great Game is no other than Archaon. The mortal champion of Chaos, accepting gifts from all gods, but pledging himself to none. Archaon is a mortal, who is speculated to have lived for eons, having ushered in the end of the world that was, and potentially having destroyed other realities since then. His ultimate goal is to pierce into the realm of Azyr, and destroy the last bastion of Order and Sigmar along with it.
The Dark Master
Belakor, the first Daemon Prince to have ever existed, as Archaeon, has existed since the formation of the world that was. Indeed prior to the existence of any Everchosen having been crowned, the ruinous powers would compete over his soul as they now do for Archaon. Belakor would go on to betray the Gods, in an attempt to serve his own purposes, and would in turn fall right into their trap. Cursed to forever crown the Everchosen, but never become him, Belakor lives in a state of pure envy. Envy of the great Archaon, to whom so many swear their loyalty. Belakor, seeks to usurp Archaon’s place within the eyes of the Chaos Gods, and return himself to the glory of his past.