Lucius relationship with his son Draco, a role reprised by 14 year-old Tom Felton (Anna and the King, The Borrowers), is vital to the story, as well as the key to understanding why Draco is such an antagonistic bully. Draco has a monstrous home life, says Isaacs. Lucius bullies him, which makes Draco bully others. Hes a chip off the old block.

The true nature of Lucius and Dracos relationship was surprising to young Felton. I always thought that theirs would be quite a loving relationship, since Lucius and Draco are both really mean people, but I think theres actually something quite scary going on between them, Felton observes. Draco always gets the rough end of the stick and is quite afraid of his father. I was a bit daunted when I heard Jason Isaacs was going to play my Dad, but hes the nicest guy youd ever meet and we just clicked!

Isaacs, in turn, found Feltons performance in Harry Potter and the Sorcerers Stone to be so convincing, he arrived on set expecting him to be this thoroughly unpleasant, slimy kid. In fact, Tom is a tremendously charming young man and very professional.