Gavalle was an only child, born in Lyon, France in 1961. Her parents died in a fire at a cinema when she was twelve. She became a police officer after leaving school. She started working for the military branch of the United Nations in 1985. Her vocal opinions about the political machinations there earned her the nickname "Le coquin".
In November 1987, Gavalle became a part of UNIT. By March 1988, she was in charge of the UN military complex on Réunion, where an alien, Tko-Ma, had been kept for twelve months. Two months later, on 4 May, it escaped and slaughtered all the soldiers except Gavalle. He erased her memory of their encounter, but implanted a trigger word in her mind. When she heard that word, Njah-Ma, she would become his mind controlled servant. She disappeared after that, turning up in 1991 at an airport in Nice, not knowing what had happened to her in the interim.
She was removed from military service, signing a non-disclosure agreement first. A new home in London was provided for her, and she worked for a publisher as a translator of comics like Tintin, Asterix and Lucky Luke
After being contacted and agreeing to work for John Doe, Gavalle met Tko-Ma a second time in 1993. He erased her memory again, but shortly thereafter used the trigger so she would help free her new master from his dimensional prison. She killed Charles Dickinson when he begged her not to do so. Ironically, the energy released through the opening to that dimension disintegrated Gavalle. (PROSE: Instruments of Darkness)