There’s a well-worn literary plot in which a modern American is sent, by some contrivance, to medieval England. Mark Twain likely invented the genre in 1889 when he dealt a time-bending crowbar blow to the head of his protagonist in A Connecticut Yankee in King Arthur’s Court . The trope has endured across the decades through a library’s worth of children’s adventure books as well as films like Sam Raimi’s Army of Darkness and the Martin Lawrence vehicle Black Knight . Bill and Ted famously wound up in a 15th century castle, where they came face to face with their beloved iron maiden—no capitalization, unfortunately for them. These fish-out-of-water tales typically deal with the perceived gulf between the technology, brutality, and enlightenment of the writer’s era and those of the medieval period. Poison Ruïn have always seen more similarities than differences, especially for the people at the bottom of the feudal system.…