A scholar at Columbia University, Gabriel and his wife Andrea were expecting their first child when Gabriel found Andrea brutally killed by her own hand. After months of grief, Gabriel sought solace in the priesthood at the Cathedral of St. Benedict; but three months after being ordained, he was possessed by the demon Catherine, a centuries-old witch cursed to Hell who had possibly possessed Andrea. Forced to tear out his own right eye, Gabriel fought back, branding his chest with a red-hot cross and driving Catherine out. As he walked out, he met Desadia, a clairvoyant and precognitive woman with his wife's words and voice, but no memory of her own. Desadia assisted Gabriel as he became an exorcist.
Much of his history is unknown, but in the 1970s he worked out of the 13th floor of the Empire State Building, exorcising Catherine from his former teacher Father Artemis; a demon of Darkness and Slime from Veronica Miller, daughter of exorcist Dr. Craig Miller; a demon calling itself Satan from Satanist Mr. Chesterton; an unnamed demon from the infant Jenny Christopher; and Belial, Elima, Nirrem, Pythonissa, and Saphira from the corpse of Esteban Ramirez. At some point he exorcised demons from Jason Maldonado, though one remained hidden within him and would later merge with Maldonado as Soulfire. In the modern era, he helped Agatha Harkness use the Fantastic Four's love to drive Nicholas Scratch from the possessed Franklin Richards.
Constantly plagued by demons, Gabriel occasionally descended into drinking binges often aborted by Desadia. Demonic influences briefly inverted the cross on his chest, but the spirit of Andrea merged with him to drive Catherine from presidential hopeful Senator Bill Bohannon. The fate of Desadia and Andrea is unclear, but they were taken from Gabriel via the demon Vermiphage. Gabriel lost his faith, making a living selling fake exorcisms as new age therapy. Hellstorm recruited Gabriel to oppose a demonic Hellstrom impostor, but Gabriel was devastated after backing Rev. Joshua Crow and learning that Crow's faith healing was actually placing Souls of the Damned into coma victims. Descending into alcoholism, Gabriel was seduced by the Asura, assassins of "Heaven," who filled him with the narcotic sacrament K, made from angels. His will subverted, Gabriel stole the Breathing Gun and assaulted Hellstorm, but when the K was abruptly purged from him by Hellstorm's mystic wards, Gabriel suffered severe withdrawal and was left in a deep stupor. He was last seen at Fire Lake mansion under the care of Isaac Christians (Gargoyle).