The Fallen One

The Fallen one was known as the first Sin bound. Beings carrying the sins of the ancients ones and are cursed with great power destined to bring about the end of the world. The Fallen one was once a young andelic woman, a priest task with guarding the heart of the fallen. It was said she had a great beauty about her that would bring an honorable knight to ask for her hand. Though when the Volza began their march on the andelic nation, he was called to duty. To save his people and protect the woman he loves.
Though when she heard he was to go to the front lines she feared for his death as she heard the red knight of the volza would be leading the charge. Fearing for her loves life she snuck into the main chamber of the temple and took the heart into her bosom. The power that surged through her would be enough to save her people and end the war. Though sadly she was too late to the battle and was there just in time to see her man ran through.
In that moment she was filled with anguish that quickly turned into rage. Unleashing her newfound power upon the enemy and ally alike. All were left lifeless husk upon the ground as she rushed to the corpse of her love. As she made her way the bodies of the now-dead rose up to serve her will. Though when she tries to raise her love she was left with nothing.
With nothing left she marched her newfound army of the dead upon the Volzian army. Wiping out each fort they held and even marching all the way to the heart of their lands only to curse it and them to sire no more upon these lands. The Volza would become a footnote upon history about what price you pay for conquest.
Though that was not the end. When she returned to her native land triumphant over her peoples' enemies. She was met with fear and betrayal. For they have set a trap upon her return to seal her deep into the earth, to break her wings which had turned black as sin, and to leave her power drained. Though before they had her sealed away she placed a curse upon her people. That no andelic shall ever live to see the next age and that when she is set free she will show the world her pain.
Even now her power still surges as dead rise to free her from her prison. Thus she was labeled sin bound and would only be the first of her blighted kind as mortals shall always repeat their past.