The guy tortures himself? Yeah, it's that intense. Jason Isaacs (Lucius Malfoy) is really into this role. He recently gave an interview with Ain't It Cool News stating that:
"...Harry Potter, it's been such an enormous part of my life for years now, and almost everything I do, I knock myself out to try and make things real-- I research them, I over-research them... I steep myself in it and torture myself at night trying to make something interesting and believable and human... You really have to hit the ground running."
But there's a lot more than Harry Potter in this interview, click on the link above to get the scoop on Isaacs.