"Human beings are always trying to bend and manipulate time to be in their favor and trying to defeat the ravages of age," he tells "Reuters" of his new movie, in theaters Friday. "And vampires are eternally young, although it'd probably be very annoying to be turned into one at 97, or 6. And then how they attack and feed off their prey seems very sensual and erotic -- biting the neck. You don't have to be a vampire to partake in such activity, but it takes it to an extreme. Blood is the liquid of life."
Wearing the fangs was "easy!" Farrell adds. "They do the mold, then file them down, and you don't even notice them wearing them. And it's great fun. You put them in, and instantly, because of all the films you saw as a kid, you start acting a certain way."
Farrell says he was a "huge" horror fan as a kid.
"Growing up I loved "Nightmare on Elm Street," "Halloween" and "Friday the 13th," and there was nothing like being scared. And still to this day, just sitting in the cinema and being frightened and sharing laughter -- there's nothing like it," he says.
He was eager to take on lighter roles this year.
"I felt like I'd had four or five years where I'd done more dramatic pieces and played characters that weren't really having a good time in their lives for a variety of reasons, and I'd wanted to do something lighter. Then these two films ["Horrible Bosses" and "Fright Night"] came along and it was happy days -- time to go and play," he says.
Of doing a horror remake, "I was dubious at first," Farrell admits. "I loved the original and you like to think of yourself as mixing things up and being a bit original -- and this is a remake of a vampire film in 3D. That's kind of three for three in unoriginality."
"But I felt I was in good hands with [director] Craig Gillespie who did "Lars and the Real Girl." I was a big fan of that, and I just loved the script. I didn't want to like it, but it was a blast of a read," says Farrell. "And playing the villain was great, although I think my character's more on the periphery than he was in the original."
– The Hollywood Reporter