One of Isaacs' most famous anecdotes involves the moment he found out his character, Lucius Malfoy, was completely absent from the sixth book, The Half-Blood Prince. He was at a midnight bookstore release event signing books, surrounded by over 10,000 enthusiastic fans and live TV crews. Hoping to see his future storyline, he asked a bookstore employee to sneakily look through the book and fold down pages featuring Lucius. The plan backfired when a young boy casually walked up to the doorway and spoiled the news, telling Isaacs that Lucius was actually stuck in Azkaban prison and not in the book at all. Devastated by his temporary "unemployment," Isaacs had to spend the next two hours smiling brightly and signing books for ecstatic children.