EW has a new interview with Ralph Fiennes. Here is the segment where he discusses Voldemort:

“That’s actually the hardest to do because you have to personify evil, and there’s such a history of cliches and villains and monsters. You’ve got to struggle not to play all the obvious notes. And with such extreme makeup, such an extreme look, that’s the challenge. Also, the style of the movies is so strong. The movie itself is its own machine, and you’ve got to fulfill a function of a bigger machine. It would be good to keep the sense of some kind of real psychology going on, even in all the special effects and everything.” That is, assuming that Fiennes reprises his role as Lord Voldie for the final movies, which he has every intention of doing. I’m not officially contracted to the last ones, but I think that’s in the cards. I want to do it. It’s just that they haven’t got a script yet, so the deal side of it isn’t in place. But the indications are that it’ll happen. Watch for the Dark Mark in the sky.