In the 1800s, Dorian Gray was Oscar Wilde’s lover (a situation implied but not stated by Jenkins). He was very heavily involved in magic and had a narcissistic personality. Dorian had commissioned a portrait of himself and bound his soul to it meaning that every excess he committed transferred to the painting. He inspired Oscar Wilde to write 'The Picture of Dorian Gray' which was really a cautionary tale about using magic.
In modern times, Dorian Gray owned club effigy and an art gallery under the alias DG Trust. He used the art gallery to hide his original portrait. At club effigy he found a way to make a photo mosaic portrait out of pictures of the club patrons. The hundreds of people who attended his club ended up absorbing his sins. The price for Dorian’s immortality is that he was unable to feel.
Real Life Counterparts
Dorian Gray is the main character of Oscar Wilde's book The Picture of Dorian Gray. He was a rich and extremely beautiful young man, who, depressed with his own mortality, sold his soul in exchange for eternal life and youth. Like his in-universe counterpart, Dorian's sins were transferred into a magical painting, which became more and more hideous every time its owner made something amoral.
Wilde's real-life lover/muse was Lord Alfred Douglas, known as 'Bosie', who was the dissolute son of John Sholto Douglas, 9th Marquess of Queensberry, the thuggish peer who gave his name to the 'Queensberry Rules' for boxing.