Funny seeing Hammer's Dracula as a Van Helsing-like character for once.
It's something the way that Hammer shuffles the roles around in their films. In one movie, Christopher Lee is Dracula. In another he's Kharis the Mummy or Frankenstein's Monster. Cushing could be a rather villainous Dr. Frankenstein or a heroic figure such as Van Helsing or Sherlock Holmes. Here, Lee takes on the role of the Van Helsing-like professor with an understanding of the supernatural and it's Peter Cushing who plays the villain of the picture.
It's a shame that we didn't get to see more of the role reversal in play. Christopher Lee and Peter Cushing only had two scenes together, but there were two of the best in the film. I think that Cushing is equally gifted at playing the hero or the villain, but I still like Christopher Lee better when he's playing the nastier characters. Even so, I did enjoy getting to see him play the hero for a change. He's by no means bad at playing a hero. It's just that he's so great at playing the villain.