William Dupont was an avid medieval and fantasy fanatic, essentially a nerd from the 70s growing up on D&D. In his older life he became a tour guide primarily, travelling around Europe showing people historical landmarks from the middle ages.
His travels took him all over the world. Dupont was scouting in Chernarus for new tour expeditions, and took a particular fancy for the castles there.
He spent a year in Chernarus, despite all the political turmoil, he enjoyed the culture. Until one day he witnessed an atrocity, people murdered in cold blood, Dupont was hiding, but witnessed it all. The psychological trauma took an impact on William, He was never the same again, retreating into a fantasy world and being diagnosed as clinically insane.
During the outbreak, the asylum where William was held lost power, doors were open and people flocked out.
William has since been wandering around Chernarus in his own delusional world.