On Good and Evil

The god of time, having created the universe, sees harmony all around him, but feels that there is still something very important missing—a companion with whom to share all this beauty.
For a thousand years, he prays for a son. Not entirely sure to whom he prays, given that he is omnipotent, the sole, supreme lord; nevertheless, he prays and, finally, he becomes pregnant.

When he realizes he has achieved his heart's desire, the god of time is filled with remorse, suddenly conscious of how fragile the balance of things may be shattered. But it is too late and the child is already on its way. All his lamentations cause the son he is carrying in his belly to divide into tow. And there u have it... just as good is born out of the god of time's prayers so too Evil is born out of his remorse—twin brothers.

{paraphrased from the devil and miss prym}