Ahriman and Ahura Mazda, they are gods in the Zoroastrian Mythology from Persia and they are twin brothers. In stories like this, when there is good, there would always be evil.
Thus Ahriman was the evil one, he was the force behind anger, greed, envy and other negative emotions followed by chaos, death, diseases and all the bad things in the world
While Ahura Mazda was the supreme diety, the creator of earth, heaven and humankind. He was the force behind all things good and everything positive in the world.
Their story started when they were still in their mother’s womb. Their father, Zurvan anticipated that Ahura Mazda would be born first, so he ordained that between the twins, the first that comes out from the mother’s womb would rule the world.
He shouldn’t have said it out loud.
While in the mother’s womb, Ahriman heard the pronouncement. Being a supreme being, he was more than a mere baby and understood every word of his father. So as soon as he heard what the father ordained, he ripped open his mother’s womb and slowly but hastefully walked to find his father to receive his father’s promise.
He went to his father and asked for the power to rule the world, even lied saying that he was in fact Ahura Mazda, but the father did not believe him because the time wasn’t right and he was dark. While the confusion was still going on, Ahura Mazda appeared and his father immediately knew in his heart that Ahriman was lying and right then and there made Ahura Mazda he ruler of the world.
Enraged, Ahriman reminded his father of the promise he made and that he was technically the first born thus making all this ordeal unfair. Hearing this, Zurvan could not go back on his word thus he finally made Ahriman the ruler of the world BUT with a condition that after nine thousand years, Ahura Mazda would then reign supreme.
With this, Ahura Mazda created the heavens and brought light, beauty, goodness and life into the world while Ahriman brought darkness, ugliness, evil and death.