Similarly, Simon explained that he got the idea that to show how little Lancel cares about his physical appearance, he intentionally grew out his own fingernails for three months without cutting them. When Lancel is having the Seven-Pointed Star carved into his forehead in episode 5.4 "Sons of the Harpy", the character grips the wooden arm of his chair in pain so hard that his nails break. For this shot, Simon weakened the long nails on his right hand by discretely cutting vertical lines into them, to make them break when he gripped the handle very hard. Simon's fingernails are actually breaking and bleeding in this shot, on-camera, with no props. As he said, "I put my hand on the side of the wood, I squeezed, and my nails broke. And we got the shot! It's used in the footage, my actual nails being broken. It was so worth it!"
Simon said that an unfortunate side-effect of this happened in the preceding episode, "High Sparrow": when the Sparrows burst into the brothel and Lancel drags the old High Septon out onto the street naked, he accidentally ended up unintentionally gripping him so hard that his long nails cut the other actor deep enough to draw blood. After the shot was done he looked down at his hands and at the other actor's bloody ribs, and realized he had his blood under his nails.
Due to his commitment to method acting, because Lancel is a barefoot penitent starting in Season 5, Simon also doesn't wear shoes between takes (other actors playing Sparrows/Faith Militant will put shoes or slippers on between filming due to how cold it is on set).