Image source: Paizo Publishing.
Asmodeus, the “False God”, is the supreme archdevil and lord of the Nine Hells. His power is swollen by divine magic, and some mortals worship him as a god of power and corruption; however, he is not recognized as a deity by the Celtic Pantheon or their followers.
Asmodeus is strengthened by corruption. Every time a mortal knowingly commits a sin, Asmodeus grows stronger. His priests, few though they may be, convince their followers that true power can only be achieved by abandoning moral codes and concerns.
NOTE: The following information is not common knowledge to the people of Miklagard. You should not assume your character has access to this information without a successful Religion check.
Asmodeus was born an angel, the exarch of a noble and kindhearted deity. At first, Asmodeus was the most beautiful and zealous servant of his master — but over the eons, he became corrupted. He desired his master’s power, and so he forged a plan to overthrow him. The deity’s other angels followed Asmodeus, enthralled by his charisma. Backed by the traitorous angels, Asmodeus struck down his master and absorbed their divine power.
With their dying breath, the fallen deity placed a twofold curse on Asmodeus. He and his co-conspirators were mutated into hideous devils, losing their angelic beauty and grace. Furthermore, the deity transformed their astral dominion, once a shining heaven, into a nine-layered prison. Outside its walls, Asmodeus’ power could not follow, and he would be merely a fiend. Only by remaining inside could Asmodeus exercise his full deific power. Thus, the devils and the Nine Hells were born.
The Pact Diabolus
Asmodeus had claimed the power of a deity, but had been mutated and restricted to his astral dominion. Refusing to give up, Asmodeus devised a plan to acquire more power, enough to break the seals on the Nine Hells and win his freedom.
The deities of the Celtic Pantheon were frustrated with the mortals, who often committed evil acts. Asmodeus proposed a new system: when mortals died, their souls would be sent to the Nine Hells, where the devils would punish them for their transgressions. With the threat of damnation looming over them, mortals would choose to avoid evil acts, and live as the Celtic deities wished. The Celtic Pantheon saw reason in this, and signed Asmodeus’ contract, the Pact Diabolus.
Centuries later, however, Asmodeus did not deliver the desired results. Mortals were sinning more than ever, despite the real threat of damnation. Belenus traveled to the Nine Hells to investigate, and found that Asmodeus had been busy. He had transformed the plane into an enormous prison, where the souls of countless damned mortals, tempted to evil by the devils, were tortured and gradually transformed into more devils. Outraged, Belenus claimed Asmodeus had broken the contract. Smug and glutted with power, Asmodeus replied:
Read the fine print.
Creation of the tieflings
From this day on, Belenus swore to foil Asmodeus’ schemes. Their proving ground was the mortal realm, where Belenus promoted kindness and honor, while Asmodeus urged corruption and deception. They fought many subtle battles for the control of mortal souls, neither gaining any significant advantage.
Centuries ago, Asmodeus devised a scheme to corrupt the humans that Belenus held dear. To accomplish it, he sought out the help of Branwen, goddess of love and Belenus’ sister, with whom Asmodeus had a forbidden affair. Asmodeus proposed his plan: to curse a fair and pureheated mortal with infernal blood. With Branwen’s power, he could make the curse infect any who had intercourse with a cursed human. Thus, he planned, the curse would infect more and more humans as they gave in to temptation. Branwen was appalled, and refused to lend her power to his plan. In a fit of rage, Asmodeus slew Branwen, shattering her power into pieces. He collected some of her power, but not enough to create the curse as he had pictured it. Nevertheless, he moved forwards with his plan.
Asmodeus selected the purest, most kindhearted human he could find: Esvene Kulenov. Asmodeus deceived Esvene and slept with her, instilling his infernal curse in her blood. She was transformed into the first tiefling, and passed her curse on to her children and descendants — although not to her sexual partners, as Asmodeus had originally intended. The tiefling race has been a spiritual battleground for Belenus and Asmodeus ever since, as they war to win the souls of the cursed race.