Diabolique was seemingly a six year old girl, who continuously sought out new foster parents, which she killed before moving onto new ones. At some point she became the daughter of Randolph DeGuzman, who was trying to assemble the pages of the Darkhold and slay Victoria Montesi. She acted as the loving daughter, while in actuality she was sacrificing several Darkholders with the aim of enchancing her power and creating Playmate. DeGuzman realized that a large number of Darkholders had gone missing and encountered Diabolique slaying her own mother. To keep him happy, she promised to give him a glimpse of Chthon knowing it would drive him mad.
Diabolique moved on to a new set of parents, Blanche and Merle Haverford and spent a week with them before killing them in exchange for three questions from the Whisperer which were all aimed at finding more information about Victoria Montesi. She also gained information from Victoria's fathers files in the Vatican.
She later surfaced in New York City, having found another couple to be raised by and began another killing spree to enhance Playmate. Her new parents managed to break free from her control and killed themselves, this brought Diabloquie into contact with Lt. Michael Badalino who was investigating the deaths. She wanted to make Badalino her father but changed her mind when he transformed into Vengeance. He discovered Playmate killing another person and Diabolique sent Zoroaster to aid Playmate. She then sensed Salomé whom she missed to take on as her mother. Salomé only agreed with Diabolique could kill Vengeance. She pulled out a voodoo doll and injured Vengeance. Vengeance managed to destroy Playmate and left her powerless. Salomé saved Diabloqiue by teleporting Vengeance away and agreed that there was potential for a future collaboration but she would need to create a new Playmate.
Diabolique ended up in a childrens hospital, unable to create a new playmate. Here, she befrieneded Rebecca Taylor. She was tracked down by Mike Clemson who wanted Vengeance dead and took her to Reverend Nice to regain her powers. To this end, they sacrificed the Reverend's wife Wendy Sue to become her new playmate, and using her new power she killed Rebecca and framed Vengeance for her death. She teleported away and her current whereabouts are unknown.