At a very early age, the Demonic Three all found their way to a hidden school of Black Magic on the edge of the Flatlands. It is suspected that Balthus and Zagor were sent there by their fathers, both of whom were known to have practised magic and to have a certain level of influence in these matters, but the method of Zharradan's arrival is unknown. As it thought that he is the son of a Hell Demon and one of the Hag-Witches of Dree, it could be that one of those harridans - perhaps even the Women of Dree, who took care of him in his infancy - conveyed him there herself.
For a period of about a decade, these three trained under the infamous Volgera Darkstorm, surprising even this depraved old horror with their natural aptitude. So gleefully malevolent were they, that it was a common occurrence for them to sneak away from the school and go deeper into the Flatlands, seeking the camps of Horse-nomads to burn or wither. Each one had a favourite type of magic. Marr was a lover of Necromancy, while Dire was better skilled in the arts of Battle Magic. Finally, Zagor was an expert on Elemental Magic.
At the age of seventeen however, they grew tired of Darkstorm's increasingly rare and stilted lessons, for he had begun to fear them and now sought to limit what he taught. However, they confronted him in open battle and cut him down with a carefully disguised Rain of Knives spell. Congratulating themselves on this bloody murder and wishing each other the luck of the Dark Gods, they went their separate ways.
Balthus knew exactly where he was headed, and moved south towards the Craggen Heights, avoiding the Forest of Yore, its scent of Goodness making him feel physically ill. He soon came to the dark castle that his grandfather had built and was now inhabited by his father - both were themselves warlocks of no negligible power. As his father embraced him, Balthus slipped a poisoned dagger between his ribs and claimed the citadel for his own. He began to build up his Goblin and Chaotic army, seeking to prove to his rivals just how evil he could be.
Zagor journeyed north with Zharradan for a while, skirting Darkwood Forest and onwards past the Moonstone Hills, where the other peeled off. Eventually, he reached Firetop Mountain, which he had seen in Demon-sent dreams for a long time. Using all his arts of necromancy and wizardly persuasion, he amassed a terrible force of Orcs and undead, and marched directly on the Dwarven stronghold within. Whilst some fled and were never caught, most perished and provided yet more deathless troops for the Evil wizard.
As for Zharradan, his movements were almost impossible to trace, though a burning Elven settlement here or the butchered corpses of a Woodling village there suggested that he had passed by. Upon reaching the heart of the Moonstone Hills he simply vanished, only to suddenly reappear years later with incredible power and influence. Disguised a prospector, he took command of a number of natural caverns and was astonished to discover that there actually was gold down there. The revenue of these Yellowstone Mines enabled him to hire or "acquire" many powerful allies and servants, and to build a huge army rivalling that of Balthus.