During the Black Plague era, there was a doctor called Bartholomew Ortez. One day he came home to find his wife and two children dead. Later that night, when he was praying to Virgin Mary(He's Catholic 'cause everyone was back then), he was approached by red mist, and a disembodied voice--the Scarlet King--that said it could help him eradicate all disease from the earth--the true Pestilence, the ancient affliction of Mortality.
Dr. Ortez agreed, and the deal was sealed by him putting on a mask made from human bone(thus explaining the x-rays in the actual document). It was glued onto his face with a black liquid, rotting his true face away. He quickly found out that, by touching people, he killed them. That night, he begged the Scarlet King to remove his powers. SK responded to this, saying that this was the first step to immortality. Ortiz was given an everlasting supply of mysterious dark liquids, and a bottomless, black leather bag to hold them in.
While he was sleeping, he was administered the dosage of the liquid, forcing him to live forever, all part of The Scarlet King's plan. Now, Ortiz could be a host for the King, furthering his goal of wiping out Humanity so he could return to Earth and rule it.
However, due to his great intellect, Ortiz can, for the most part, repel SK's instructions. However, years of his mind being inhabited by the Scarlet King has clouded his senses, forcing him to believe the lies told to him by the Scarlet King. He is miserable with his eternal life, and desires to return to his family in Heaven. The Scarlet King will allow him the pleasure of death, but only if he can convert 40% of the human population into mindless husks.
In an alternative ending to my book, he completes his quest. As the Scarlet King begins manifesting himself, Ortiz feels his mind unfogging, his mask finally relinquishing it's grasp on his face. He is now nothing more than an embalmed corpse. In his last moments of life, as the sky turns scarlet, signaling the arrival of the End of the World, and the angel Uriel leaving the gates of Eden, Ortiz finds the cemetery containing the bodies of his wife and children.
He mourns, and crushes his mask in his hands, regretting allowing the destruction of the very world he hoped to save.
He sobs, and dies on the grave of his wife.