Poisoned Kayla Brady in 1987
Became the Riverfront Knifer in 1988
Took Kimberly Brady and Kayla Brady Johnson hostage in 1988
Took Kayla hostage again after breaking out of prison
Attempted to kill Steve Johnson in 1990
Harper Deveraux was a rich and powerful senator who came to Salem with his wife Anjelica in 1987. Harper soon became involved in the mysterious computer disk that Victor Kiriakis and Serena Colville were after. When the disk ended up in his possession he was almost killed by an explosion set up in Mike's lab where the disk was stashed. Harper enlisted the help of Steve Johnson to fake his death, but the blanks in Steve's rifle were replaced with real bullets, and Harper fell into a coma after being shot by Steve.
Harper recovered and hired Kayla Brady to be his son's nurse. Jack had come to town and was sick with Hodgkin's disease. When he and Kayla married Kayla moved into the Deveraux mansion. Meanwhile Harper learned that Jack's true family was looking for him, so to keep his identity a secret he stole the adoption papers from Jo Johnson. When the papers turned up missing he thought Kayla had them so he tried to kill her with poison. Later Melissa Anderson was arrested and charged with the attempted murder.
When Harper's wife Anjelica became pregnant Harper ordered her to have an abortion. Angelica refused, not knowing that Harper was hiding a secret from her. When Jack learned he was adopted Anjelica learned that Harper was sterile, so the father of her unborn baby was Justin Kiriakis.
Harper, who was angry at the women in his life for betraying him, began attacking the women of Salem. He attacked Eve Donovan, who survived but war scarred by a knife slash across her cheek. Harper then attacked, and killed Janice Barnes. His next victim was Kayla Brady, who survived the attack but went deaf and mute as a result. Harper then attacked Kimberly, who was working undercover as a prostitute. Kimberly survived, but lost the child she was carrying.
When Kayla recalled the identity of her attacker she rushed to tell her sister Kimberly. Unfortunately Harper took them both hostage and planned to finish the jobs he started on them Harper was eventually stopped by Steve Johnson. Harper was sent to prison, but vowed to get revenge on Steve.
Later that year Victor Kiriakis, with the help of Jack Deveraux, arranged a jail break so that Harper could leave the country. The scheme didn't go off as planned; Harper was shot while trying to get to the airport. Jack took him to the Riverfront Clinic where he took Kayla hostage again. Steve rescued Kayla, and Harper was sent back to prison once again.
Harper later escaped from prison in 1990 and tried to stop Kayla and Steve's wedding. He fell to his death while fighting with Jack on the bell tower.