Rosacarnis

6th Century BCE - 539 BCE
Rosacarnis was the product of a rather grim love affair between Death of the Endless and the Archdemon Nergal. Nergal had escaped from the Void long before Hell was a thing and had been living on Earth for many centuries, gaining a cult of followers and worshipers when he met Death of the Endless. Death was living among other pilgrims from the Void, helping them develop a pantheon among Earth's humans in the lands known as Babylon, Sumeria and Akkad.

As Nergal sought to partake in some of his worship, he found a way to merge his cult with the developing church and worm his way into the pantheon. Once he became vital to the flow of worship, the other gods decided to arrange a political marriage between the demon and the "goddess" known as Ereshkigal (Death). Rosacarnis was the result.

539 BCE - 2000 CE
When the worship dried up, eventually Negal chose to take Rosa with him back to the Void. Once returned to the Void, Nergal was surprised to find that an archangel named Lucifer had now united much of the infernal realms under the banner of Hell. Negal was a powerful demon, but he was too smart to challenge Lucifer and instead did his best to broker political power in the infernal courts. To accelerate this process, Nergal tasked his daughter with becoming a succubus. When she was not on Earth collecting souls to grow Nergal's wealth, she was in Hell being used as a pawn for her father's political machinations.

2000 - 2004
In the 1990's, Nergal had ran afoul of a human mage and exorcist, John Constantine. After the better part of a decade exchanging threats and enacting ploys against the Laughing Magician, Nergal sent Rosacarnis to seduce Constantine. Rosacarnis offered the mage intel on his missing lover, Zatanna Zatara, in exchange for him siring three children with her. John, being the horn-dog he is, agreed to the deal and only after the first tryst had been concluded did Rosacarnis tell John that she was the daughter of Nergal. Their relationship was understandably rather awkward for the next three years. When the deal was completed, Rosa gave John the information he needed but warned him that the next time they saw each other, she would use his own children to ruin him.

2004 - Present
The threat was ultimately rather hollow as the next time she saw him, Rosa was barging in on John requesting his aid in helping to protect her, her angelic lover, and their unborn child from the Host of Heaven. Despite John's efforts, the angels took both the father and the child and also attempted to kill Rosacarnis, but thanks to John's friend Chas, Rosa was spared that fate, though John still attempted to exorcise her.

Following John's aid, Rosacarnis and John became uneasy allies, with their relationship slowly transforming from enemies to friends, and even to lovers and allies. It was a bumpy ride for the next decade, but ultimately after Rosa betrayed the First of the Fallen and her own father for John, and was captured and tortured for it. Eventually, John chose to make a deal to get her freed and in so doing, earned the demon's trust.

Supplemental Reports

 * (Submitted by Four-Eyes) The child of Rosacarnis and her angelic lover remains a topic of speculation. Though the angel father described himself as "Tali" to John, I have my doubts. No known angel exists in records by such a name ever prior to this incident, and why would the Heavenly Host go to such efforts to retrieve some no-name angel? Curious, huh?
 * (Submitted by Four-Eyes) Although her true form resembles that of a classical demon with red leathery skin, horns, bat-like wings, razor-sharp fangs and claws, Rosa prefers the human form she took to seduce John Constantine—a form that some have likened to a Hispanic version of Zatanna Zatara.

Resources

 * Immortality
 * Seductive
 * Shapeshifter
 * Telekinetic
 * Telepath
 * Enhanced Senses
 * Infernal Sorcery

Trivia

 * She can't cook, at least nothing suitable for human digestion.
 * Thanks to Endless heritage wards against demons don't work on her.

Links and References

 * Appearances of Rosacarnis
 * Character Gallery: Rosacarnis