Lady Death (or Hope, her original name) began 'life' in Europe during the medieval era. Her father, Mathias, was a sorcerer of great power as well as a feudalistic warlord. Mathias was also a 666th generation descendant of the fallen angels, a strong contrast to Hope's mother, Marion, who was of such purity that her bloodline reached all the way to heaven. Before her marriage to Mathias, Marion was married to the Viking Agnar, to whom she bore two daughters, Vulnavia and Vandala, previously unknown sisters of Hope. Marion's attempts to escape Mathias' brutality proved ineffectual and led to her murder at his hands. He, in turn, captured her soul for use in maintaining a gate to hell.

Mathias' aspirations for power included deals made with demonic overlords in Hell. In exchange for the souls of the newly dead, which were harvested through constant warfare, the overlords granted the sorcerer power. The constant battles eventually even claimed the life of Hope's beloved, Niccolo, who had taught her medical knowledge from distant places. It was when the plague struck the town in which Hope lived that she was forced to put this knowledge to use by saving the life of Agnes, the only friend she had. The town's church leaders saw this display and declared it unchristian. The town declared her a witch and prepared to burn her at the stake. Meanwhile, the townspeople found Mathias cavorting with demons and after a bloody struggle managed to kill the sorcerer. Unfortunately, it was their hatred he had sought all along, as it was the key to his ascension to power in hell

Sentenced to an unjust death, Hope renounced her humanity, allowing demons to transport her to Hell. There she met Lucifer, who offered her power and the advice that in hell, desire equals power. Her response was to spit in his face. He cast her into a pit, where she fought to tame two demonic wolves, which would be her companions in times to come

Meanwhile, Mathias had lead a great army against Lucifer and apparently vanquished the prince of lies. As the ruler of hell, his first action was to hunt down and kill his daughter. Hope had in the meantime decided to fight for herself and, renouncing her name, took on the name of Lady Death. With the help of the demonic blacksmith, Cremator, Lady Death fought and overcame hordes of demons only to face Mathias and learn that Lucifer was still alive. Lucifer had set out to create a creature of darkness from a pure soul such as Hope, and had engineered the entire war in hell to accomplish this task. Mathias' soul was locked away as Lucifer revealed the intricate plot he had weaved

As he had revealed to Hope, in hell desire equals power, and Lady Death took this lesson to heart as she battled Lucifer. Angry at being used for mere 'amusement', Lady Death desired nothing so much as the death of Lucifer. After a fierce battle, she struck the mortal blow which apparently killed Lucifer. With his dying breath, he cursed Lady Death to never again walk the Earth until all life on that planet was extinguished

Her solution was a pragmatic one. She would wipe out all life on Earth. Hell itself was transformed into a gigantic graveyard where Lady Death ruled supreme. For four hundred years she attempted to wipe out humanity until at last she met Ernest Fairchild. He proved to be her most loyal and destructive servant ever, and at last her goal seemed to be approaching completion
Hell was then turned upside down as the vampiric goddess, Purgatori, attempted to defeat Lady Death and take her god-like blood as a prize. It soon became apparent that Lucifer was still alive and well, having concocted an incredibly complex scheme to further evil through Lady Death. By aiding the destruction of life on Earth, Lady Death had performed splendidly for the Prince of Lies. Lady Death was completely overcome by Lucifer and her demonic side emerged, creating Lady Demon. This demonic incarnation cast Purgatori out to Earth and became Lucifer's consort

This did not last however, as Marion's spirit contacted Lady Demon and Lady Death returned to her senses. Absorbing her mother's angelic powers, Lady Death returned to battle Lucifer. This time her defeat seemed certain, until she remembered a transdimensional portal known as Heaven's Gate was said to destroy creatures of pure darkness. With her last strength, Lady Death managed to kick the dark prince through the portal, effectively destroying him

Weakened, Lady Death found ruling Hell far more difficult. Lucifer's defeat was said to foretell the Judgment Era of the Fallen Angels, but Lady Death merely wished to return home to Earth. Before she got to test the theory she was cast out of Hell through the vile cunning plans of Pagan, the court jester of Hell. She ended up floating in a void known as the Unknown, a place where all theologies coexist

For a brief time she returned to Earth through the efforts of Evil Ernie. The curse proved yet effective, and she was forced to bid her emissary farewell. Returned to the void, she was unknowingly sent on a series of missions by Vandala to prove that she was the chosen one to save the Asgardian people from Genocide. Having completed the missions successfully and having destroyed a demon seeking vengeance for Lucifer's death, Lady Death went with Vandala to Asgard, where she began to learn the true nature of her existence, but was also forced to battle to save Asgard, and reality itself, from the forces of Genocide

This info is not complete, but it gives a basic understand on how Lady Death came into existance and some events that happened.