Dr. Gaines is one of the main minor villains of Supernatural TV show. He is a supporting antagonist in Season 7 of the show and was a surgeon who works at Sioux Falls General Hospital until his form is taken on by a leviathan.
He made his first appearance in episode "Hello, Cruel World". The story started from a moment when Castiel went into public water supply, all Leviathans, which were inside of him, spreaded in every water place. In park, small girl called Annie was possessed by one of the Leviathans and she he was thinking only about evil plans of Leviathans. Later, in her house, she was watching the Tv show about medicine and operations, which were provided in hospitals. She's got the interest to it. Few days later, Annie meets up with another leviathan, Edgar.She tells him that she and the others are hungry, but the Edgar is unsympathetic. Annie tells him that she has a plan. At Sioux Falls General Hospital, Sheriff Jody Mills is recovering from an appendectomy. Her surgeon, Dr. Gaines, sees a young girl alone in one of the hospital rooms and approaches her. The girl is Annie the Leviathan, and she takes his form and then kills him. Now as Dr. Gaines, he begins feeding on patients in the hospital. He is noticed by Jody Mills who escapes the hospital. Later Edgar comes by with the two swim team boys and Gaines shows them the hospital as well as providing them new hosts. Gaines later catches Bobby in the morgue investigating the body, and Bobby shoots him, but Gaines is unaffected. Bobby flees the morgue.
His second appearance was in episode "The Girl Next Door". At Sioux Falls general, Dr. Gaines and the Leviathan Head Nurse are preparing a patient for surgery - or "dessert" as they call it. The Leviathan impersonating Dr. Gaines receives a call alerting him to the Winchesters' arrival at the hospital, but he is too late to stop Bobby from driving away in a stolen ambulance with Dean and an unconscious Sam. Three weeks later, Bobby reports that the Leviathans at the hospital - Dr Gaines, the head nurse and an administrator - have disappeared.
His final appearance was in episode "How to Win Friends and Influence Monsters". Gaines begins experimenting on humans to make them more compliant. However, a small number of humans react badly to the Gaines' experiments and become ravenous, cannibalistic creatures which go on to commit a spree of murders. These killings caught the attention of the media. Dick Roman shuts down the project and makes Dr. Gaines "bib" himself as punishment for his carelessness. This punishment involves Gaines being forced to wear a lobster bib and then literally eating himself starting with his right arm. After the punishment is complete, nothing is left of Gaines except a black stain on the bib.