Maria was daughter of John Constantine and Rosacarnis. She and her two brothers, Saul and Adam, were born and grew up in a pocket dimension created by her mother. As a child, a boy named Oliver tried to rape her and she instinctively used her demonic abilities to burn him to death. This was her first kill. By the time she'd reached her mid-teens, Maria was rounding up friends to torture and murder homeless men, for fun. Upon discovering this, John broke the pocket dimension and came back to reality, bringing the kids with him. Maria left with her mother and brothers, but before she did so, she slashed John across his left cheek, scarring him. Rosacarnis had made the mission of the children to defeat John Constantine, their father. But they could not just kill him, because his life is required for them to continue to live. So they devise a plan to kill everyone John's ever cared about. Maria kills Alba Suria, but turning Alba's own power inward and killing Alba, and everyone who was in the hair salon with Alba. Maria tricks a truck driver into giving him a ride then distracts him, and his truck is driven off the edge, into a house, where Chas Chandler was staying, attempting to kill Chas. She fails, and then realizes someone is working against them.
Maria was created by Mike Carey and Leonardo Manco.
Maria is truly a half-demon and goes through a character evolution that reflects that. At first like her brothers she thinks little of murdering dozens of people at her mother's command, but unlike them she develops enough self-awareness to question both her mother's commands and the false childhood that her mother put her through. She goes from being a true blue demon to acting a lot like her father John.
Maria tried once more to kill Chas after Nergal had left his body, but doubts about her mission and non-existant childhood, coupled with her interest about a strange presence in Chas's body, stayed her hand. After finding and removing a sliver of her grandfather's essence from Chas, she and her brothers fled home to warn their mother of Nergal's presence.
After notifying her mother of her grandfather's return, Maria began to question why her mother would continue her war against Constantine - she suggested that Nergal could reclaim his throne and enact his own vengeance and that she, Rosa, Saul and Adam could go away somewhere and become a real family. Rosa, believing that her daughter was becoming weak, forced her to cut her lips open on a knife.
A New Mission
Later, in Hell, the First of the Fallen tells her and her brothers, after he killed their mother Rosacarnis, that he has to convince him to let them live. And, unlike her brothers, Maria does not beg. When the First of the Fallen asks why, offended by her not begging, she says that if this is what life is like she doesn't want to live. Liking this answer the First of the Fallen allows her to live, killing her brothers. Maria appears to very much want a normal life, and not the one she leads.