On his very first day filming the Harry Potter franchise, Isaacs was deeply intimidated to stand opposite acting legend Richard Harris, the original Albus Dumbledore. While waiting between takes, Harris completely shattered the grand illusion of the wise old headmaster by regaling Isaacs with jaw-droppingly filthy, hair-curling, and highly detailed stories about his wild sexual escapades from the 1960s. When the cameras finally rolled, Harris suddenly stared blankly at Isaacs for what felt like an eternity, prompting the terrified younger actor to twitch and sweat in a panic thinking Harris had forgotten his lines. It turned out Harris was just delivering a masterclass in dramatic timing, utilizing a terrifyingly long pause that worked perfectly for the scene.
