In ages hence, Moradin was the sole god of what would eventually become the Dwarvish pantheon. His origins are unknown; for those dwarven cultures that do tell tales of his own orgin, most myths among the dwarves point to a potential elemental origin within the planes of Earth or Mineral, possibly Magma, but details vary. Whatever his origins, though, from the very beginning he embodied the role of the Smith, for his Soul Forge was an element of his existence in the very first stories.
By the most common dwarven creation myths, he originally crafted the dwarves personally from pure iron and mithral, each of the first individually crafted at his Forge, every detail formed by his hand, in his first realm: the Caverns of the Everlasting Flame deep within the core of Magma, millennia before Moradin took up residence upon Mount Celestia. Once formed, these first dwarves were dispersed throughout the Prime to thrive beneath the mountains and hills, pushing back against the twisted forces below that would claim the soil for darkness alone, and the humanoid tribes above that would see craftsmanship and beauty shattered. His long-standing enmity against Gruumsh, god of the orcs, was formed from the moment the first dwarves walked the tunnels of the Material, and his people have been theorized to have even been the motivating force behind the initial creation of the dwarves.
His creations soon surpassed even his own divine hopes, as they — in their creator's image — produced wonder after wonder from the raw material that surrounded their homes. So great were their creative energies that their efforts soon began to manifest in other divinities alongside Moradin. First among them was Berronar Truesilver, the goddess who would shortly after take Moradin as husband, tempering him and bringing mercy to his ways. Many soon followed, every aspect of the dwarves made manifest through a power, whether good and ill: Clangeddin, Abbathor, Dumathoin, Muamman, and many others.
Despite disagreements, for a time there was peace amongst the pantheon, if uneasy. Only for a time, however. Though duergar tales vary strongly from dwarven canon, the dwarves claim Laduguer as once one of their own, and the source of the first schism amongst the pantheon. By their telling, Laduguer the Practical (as he was then known) was discontent by what he saw as shiftlessness and laziness amongst the others, he began to feel unwelcome amongst his brethren. Dugmaren was wasting his intellect on pure theory. Muamman spent too long away from the hearth, and not enough time at his work. Dumathoin was too focused on the new to care about the proven. And Moradin himself? Wasting his time on artistry that could be spent on greater production. (There are some myths that claim a spark of jealousy towards Berronar helped to motivate Laduguer, but this would seem quite out of character for a god whose attention has always been wholly on the craft.)
Speaking out against Moradin and their mutual kin more and more, the final straw is said to have come when, in exploiting a favor offered by Berronar as an olive branch, Laduguer entered Erackinor at a time when Moradin was away battling Gruumsh in the days before the Compact, intent at using the Soul Forge to prove his ways better. He crafted his own dwarves, dour and bland, empty of expression and empty of joy but skilled at all crafts. Upon his return, Moradin was enraged and banished Laduguer and his creations, the duergar, to the "wastelands of the orcs" — a voluntary departure, to hear Laduguer's words. Still, ever since, among the dwarves the god has been known solely as Laduguer the Exile.
Fewer myths are told about the departure of the brothers Diirinka and Diinkarazan; all that is known is that these twin divinities of magic, having gained some awareness of Ilsensine through Dumathoin, thought to raid its realm for power in a very ill-thought out strike. Diirinka with a portion of Ilsensine's strength, leaving his brother to the mercies of Ilsensine, who shattered the mind of Diinkarazan and left him trapped in an endless insanity within the depths of the Abyss. Placing thoughts of his brother out of his mind, Diirinka continued to flee, the magic urging him onward to Pandemonium. Once there, once safe, he offered gifts of the stolen magic of the mind flayers to his most devoted followers, not realizing that the minds of himself and his people alike would be twisted and shattered themselves by such energies, if much more slowly than his brother; and thus, the derro were born.
- The Complete Book of Dwarves, pg.7
- Deities & Demigods, pg.106
- Deities & Demigods (3e), pp.83-84
- Monster Mythology, pg.27
- On Hallowed Ground, pp.76-83