 Billy uses a wheelchair, having been paralyzed from the waist down in a freak engineering accident in India; Will happened to be on the scene and took a photo of Billy moments before he became paralyzed.Billy came across the photo after his accident and kept it as a reminder that he was fortunate to have survived.Once the house's irregularities become more extreme, Billy joins Will and Tom in a thorough analysis; after Holloway and his men go missing, Billy insists on joining Will on the rescue mission, navigating the maze in his wheelchair.