A queen who once sought to destroy the world had her heart made soft by love. For a time there was peace and she saw the world for its beauty, not as disgusting and deserving of destruction and hollowing before she lost her lover, leaving her to endure the birth of a child they concieved. Then at the young age before he took the throne, neighbouring kingdoms united to kill him and called it justice. A victory for the Light.
She would unveil her heir's body of mourning sheets and she would wail, the halls coveted by the horrible shrieks of a loss nothing can replace. The heart of motherhood would be stripped from her soul leaving only behind the shattered visage of a threat the world tried to seal away in a box, a darkness now set loose as the entity of her form takes flight and blankets the realm in a foreboding eclipse.
And her vow is so, "You took the last that remained of my light -- so now I will shroud your world in endless dark."
This is her vengeance on a world crowned by cruelty first and cloaked by the swaddling falsehoods of divinity.