Eric Simon Payne grew up in Queenstown, Illinois, to an abusive and alcoholic father and battered mother. Payne sought salvation in enthralling books and mindless violence, in pretty girls and petty crimes. He would later marry a nurse, Cory, and join the American military and serve as a Marine in Vietnam. After his tour of duty, he was left bitter and shell-shocked, dismayed by the loss of innocent life and feeling betrayed by his country. Furthermore, his wife left him for another man. He felt his once-unquestioned obedience resulted in alcoholism and the loss of his innocence, his idealism, and his wife.
Payne made his way to the Italian mob, specifically Carlo Boccino. Boccino took Payne in, treating him like a brother and giving him a job as a high-profile assassin. Payne seemed grateful, initially. However, Boccino once ordered Payne to kill a journalist that had been hounding him, named Ian Fate. Unfortunately, the pipe bomb Payne used killed Fate's wife and child instead. Distraught by the loss of innocent lives, Payne fled Boccino's employ.
Payne was sought out by the Cult of the Harvesters of Eyes, who sensed his nascent psychic abilities. Payne was led to believe the cult's promise of a new way of life and he became an initiate. Payne excelled at his training in the cult, developing a fantastic array of physical and mental powers. He eventually grew into one of their highest roles -the Reaper of Souls- the cult's assassins of death. However, when Payne learned of the cult's true agenda, to unleash demons on the world, he believed the cult had used him and that he was betrayed once more. He turned against them and left, taking the powerful shadow cloak with him. Payne struck out on his own, becoming a renegade demon hunter, calling himself Devil-Slayer. He devoted himself to destroying the cult and stopping its so-called "xenogenesis" program that would restore an ancient race of demons to domination over Earth.
At one point, the cult managed to capture the powerful object known as the Eye of Agamotto from its owner, the Sorcerer Supreme Doctor Strange. The cult's leader Vera Gemini extended an offer to Payne to return to the organization in anticipation of its triumph, but Payne refused. Although they were at a restaurant, Payne transformed into his Devil-Slayer identity to fight Gemini, gaining the attention of the heroes Valkyrie and the Hulk. The two mistakenly battled Devil-Slayer, allowing Gemini to escape, until Payne could explain. Valkyrie took Payne to her team, the Defenders, and Payne agreed to join them. Together, the Defenders defeated Vera Gemini and stopped the xenogenesis. Payne parted company with the Defenders afterward.
Payne later found his wife Cory in Israel, a member of a cult following a self-proclaimed messiah named David. Payne confronted the false prophet with the Defenders, who were seeking out and battling various demons who formed the organization called the Six-Fingered Hand. Cory decided to stay with the few remaining followers of David, and Payne went on to join the Defenders against the Hand and, ultimately, the Hand's true masters, the lords of Hell and Satan himself. When Satan's true purpose was revealed, to keep his son, the Defender Hellstorm, in Hell with him, the Defenders returned to Earth.
As Devil-Slayer, Payne served with the Defenders for a brief tenure. At one point, he encountered a homeless drug user called Sunshine. Payne helped him overcome his dependency and Sunshine clung to Payne like a loyal puppy. Later, Payne was confronted by Ian Fate who was seeking revenge on Payne for killing his family years earlier. Fate had since become a powerful sorcerer, and he kidnapped Cory, holding her life in balance as his demon servants battled Payne. Sunshine put aside his own withdrawal pains to elicit help from the Defenders, who then proceeded to help Payne defeat Ian Fate. In the final battle, Cory seemed to be fatally stabbed by Fate's demons, but it turned out to be Sunshine, mystically altered to resemble Payne's wife, who sacrificed himself.
Payne suffered a crisis of conscience, spiraling into depression, drunkenness, and attempts at suicide by standing on the edge of the matter-annihilating dimension of the Negative Zone. He once again believed his legacy was only death of the innocents around him. His attempts at suicide were punctuated only by teleporting to Earth to confront various aspects of his past, but each left him empty and void of resolution. Ultimately, he ended up in Israel and was rescued by Cory. Cory, who had since found truth and solace in Christianity, professed her love for her former husband, and he returned to her and to her faith. Payne turned himself in for the crimes he committed in the past, and was remanded to custody in Israel, and later, to the witness protection program in the United States.
Years later, Payne resumed his Devil-Slayer identity. (The details of his reformation remain to be revealed.) He was somehow contacted by an American military general to ostensibly talk about the xenogenesis plot. Payne, intrigued how a military general would know about the xenogenesis, agreed. The general met Payne at a bar, revealing himself to be Belathauzer, one of Vera Gemini's first demons to be released on Earth. He had set a trap for Payne, drugging him to nullify his psychic powers and attacking him with a horde of demonic allies. Payne pulled forth the sword Dragonfang from his cloak, the sword once used by his teammate Valkyrie. Belathauzer hoped to gain control of the shadow cloak for himself, but the cloak mysteriously transported everyone on the scene to the other-dimensional land of the dead, where Valkyrie and her allies had seemingly died in defeating the Dragon of the Moon. Payne ultimately killed Belathauzer and his demons, believing that the Valkyrie had been the force that drew him there and helped him against Belathauzer.
Payne was suffering another attack of self-conscience when he was confronted by the spectral ghost of the Flying Dutchman on behalf of the demon Mephisto. The Dutchman took Payne aboard his ghostly pirate ship and hoped Payne would renounce his soul in exchange for his offer of luxury, wealth, and pleasure. Payne refused and was deposited in the Central American village of Potega, where the country was embroiled in a civil war sparked by communist revolutionists. Psychically disguising himself as a Rambo-like soldier of fortune, Payne used weapons taken from his cloak to fight back the communist People's Liberation Army and win the favor of the priest. He continued to fight for the defense of the village, even fighting against United States armed forces who were helping the country against the Liberation Army.
Determined to defeat Payne, Colonel McCloskey, the leader of the American forces and a former friend serving with Payne in Vietnam, and Colonel Ramirez, the leader of the People's Liberation Army, decided to team up against him. The Flying Dutchman enticed the two into receiving hi-tech weapons capable of combating Payne's in exchange for their souls. They were also aided by the treachery of the Mayor of Potega, who betrayed Payne's hiding place. In the resulting confrontation, the priest of Potega was killed and Payne's shadow-cloak was believed to be destroyed. The only weapon he was able to retain was a mystical staff with a curved blade. McCloskey, Ramirez, and the Flying Dutchman confronted Payne, seeking refuge in the church, in a climactic battle that seemed to literally verge on the brink of Hell. Ramirez fell into the flames, presumably lost, and Payne doused the Dutchman with a vial of holy water, defeating him. Potega and its people were back to the way they were before Payne arrived, although McCloskey's soul still appeared bound.
Payne took the opportunity to retire his Devil-Slayer identity, realizing that he won a second chance at freedom from his past. Months later, Payne appeared on the doorstep of Doctor Strange, a dagger plunged into his chest. He was rushed to the hospital and Doctor Strange began a search for his attacker, the magician-killer, Silver Dagger. Payne survived, only to be later found at the Rosewell Sanitarium, a mental hospital in Massachusetts. By this time, Payne had succumbed to the fact that, although he and Cory had remarried, Cory had died, a victim of mob retaliation, and with her, his faith. Payne spent his time often lost in telepathic hallucinations, and his only solace was a mute inmate named Sorrow, with whom he could communicate telepathcially.
When the magical gateway known as the Nexus of All Realities became fragmented, one of the fragments somehow became lodged within Payne. This brought him to the attention of the enigmatic Mister Termineus, who was interested in manipulating events to bring about the threatened end of creation that began with the Nexus' fragmentation. He confronted Payne, giving him a gift in the form of a demon. The demon turned out to be a physical manifestation of Payne's personal "demons" he always battled with, and Payne transformed into a form of Devil-Slayer, complete with cloak, in order to battle the legion of demons that were then unleashed. Not only was his madness given form, the entire hospital and soon the city itself began to be subsumed into a nightmarish parallel dimension. The dimensional guardian Man-Thing and his wife Ellen, who were charged with reconstructing the Nexus of All Realities, teleported to the scene, and Payne turned on the Man-Thing. The battle ended in a conflagration and, as the two burned, reality began to reassert itself. Ultimately, Man-Thing reverted to his normal state, and Eric Simon Payne was reborn. The fire had apparently burned away the cocoon of suffering and madness that had been tormenting him, and Payne turned the fragment of the Nexus over to Ellen.
Thus reborn, Payne partnered with his fellow inmate Sorrow, whose sole purpose seemed to be to call people to the Rosewell Sanatorium, people who needed spiritual healing and provide such healing by allowing them to follow her to an astral plane connected to the hospital. The two appear as luminous beings to those they help, while maintaining their identity of patients at Rosewell.