Grimm, NBC’s new hour-long drama, is a police procedural with a twist: The perpetrators are all fairy tale creatures, from the Big Bad Wolf to the Three Bears. The series stars David Giuntoli as Nick, a homicide detective in Portland, Oregon, who discovers he's descended from a long line of monster hunters known as Grimms. Joining Giuntoli is veteran actor Russell Hornsby, who plays Nick’s police partner Hank.

Speaking Thursday with Spinoff Online and other members of the press, Hornsby and Giuntoli explained that the greatest obstacle to filming Grimm isn't getting into character -- it's coping with the Portland climate.

“The biggest challenge is trying to stay warm while doing your best to look cool!” Hornsby laughed.

Giuntoli, on the other hand, said the choreographed fight scenes matched the cold in difficulty, especially as the actor started off doing many of his own stunts.

“I was like, I can handle it, I’m young, I’m scrapping! And no, I was undone immediately,” he said

“After the 20th take his knees look like purple bruises,” Hornsby laughed.

“Twenty? After three!” Giuntoli corrected.

Although Nick leads a double life as cop and monster hunter, his partner Hank is completely ignorant of the secret world below the surface of Portland, something Hornsby said didn't significantly impact the way he approached the character.

“Since there are two elements of the show I’m greatly steeped in the procedural element and I lie in that world," he said. "So for me that makes it a lot easier for Russell the actor and for Hank to just focus on procedural elements of the show."

However, Hornsby revealed that as the series goes on Hank begins to become aware that Nick is hiding aspects of his life.

“As we move on further down the line in more episodes, I think the character will become a little more curious and interest will be piqued on how things are changing in the city itself with a lot of these crimes that are being committed,” Hornsby said.

“I think as the series goes on it becomes more and more difficult for my character to keep these two worlds separate,” Giuntoli agreed.

Explaining that, while in the first several episodes the world of the fairy-tale monsters and the humans are fairly separate, “As the episodes go on, the [monsters] come after me and my life, and my life includes the precinct,” Giuntoli said.

“Again, my character starts to see that things are getting a little weirder in the city, and he is seeing that the type of crimes being committed is out of the ordinary,” Hornsby added.

With each episode twisting a specific story from the Brothers Grimm, Hornsby cracked up as Giuntoli joked he hoped the writers eventually work in a fairy tale, “that allows me to sleep a full eight hours.”

Giuntoli said he was happy to see his favorite fairy tale receive the Grimm treatment. “My favorite has always been Rapunzel and we deal with that in Episode 107," he said. "It’s a wonderful episode, and Rapunzel is incorporated in a very fractured way. It would be difficult to figure out as a viewer that it’s Rapunzel."

“My favorite thus far has been the Pied Piper fairy tale, even though I’m afraid of rats!” Hornsby added with laugh.

Turning to their specific characters, Hornsby confessed that playing Hank uncovered a talent he never knew he possessed.

“I didn’t realize I had a sense of humor!” he laughed. “I am used to doing really intense dramas. The writers have weaved some very funny moments into this and a lot of levity into the script and into my character, and it’s actually a lot of fun to play.”

“I’m not as dour and dark as I normally am in other roles!” he added

By contrast, Giuntoli said he believed he had to be more grim as Nick.

“I feel I had to be very forceful and authoritarian in various episodes because these Grimm’s creatures have been raised to fear me," he said. "They run away from me when they see me on the street, and my character Nick is supposed to be this nice guy, a detective who wants a family." As a result, “Their response to me doesn’t sync with my identity and as the show goes on I try to fill that role and actually become this kind of fearful enemy of the creatures while they are around."

While Giuntoli and Hornsby play old friends and partners on the show, over the course of their talk their real-life chemistry was palpable, the two laughing and joking as they each praised the other’s work.

“It’s been an honor working with [Hornsby] because, as I like to say, he’s a youthful veteran of the world of theater and acting,” Giuntoli said.

The “youthful veteran” was equally complimentary of Giuntoli. “David is a very smart, intelligent actor and has a wonderful approach to the work as well, which is totally opposite to my approach,” Hornsby said.

Turning to the show's initial high ratings, Giuntoli explained that Grimm owes much of its early success to social media.

“For all of the followers of @NBCGrimm, we leaked the pilot episode a week in advance to them to get the buzz out there,” he said. Although he was initially hesitant, as he feared it would take away from viewership, Giuntoli was happy to be proven wrong as the show debuted to surprisingly high numbers. “I don’t know if it would have worked if it wasn’t a ‘genre piece,’ but Twitter has really helped launched us and helped us become this hit for NBC."

While Grimm marks Giuntoli’s first major television role, Hornsby has a wealth of work behind him, appearing on everything from HBO’s In Treatment to UPN’s Haunted. However, Hornsby said Grimm is different from all of his other cop roles, as he feels Hank is a more three-dimensional character.

“Hank has a more interesting personality," he said. "I think he’s a lot more well-rounded character. I’m having a lot more fun playing this role, and I think because of the concept and the show itself I’m able to add different element of Russell into the character."

Hornsby also said he wasn't bothered by the genre aspects of the show, although when he was asked to play Hank he had to give serious thought as to whether to accept the role.

“I mean, quite honestly, you’re reading it and you’re going, 'Wow, I would love to work on this show,'" he said. "But then the other part of you goes, 'Wow, how will this work?'” However, he said ultimately he thought Grimm has avoided straying into “silly” territory.

“It’s definitely a different spin on the procedural and fantasy, and I think their idea of enveloping the fairy tales with the real world is really what inspired me to want to be part of the show,” Hornsby said.

The two actors concluded by speaking about their co-star Silas Weir Mitchell, who plays Eddie Monroe, a reformed Grimm-creature who serves as Nick’s reluctant informant.

“My character [doesn’t] want Hank to know about Monroe and the Monroe/Nick relationship,” Giuntoli said. However, “In one case we use Monroe’s expertise as a watchmaker and a clockmaker and I have to reluctantly have all three of us together in the same room."

When asked how that turns out, the actor laughed: “Drama ensues!”

A new episode of Grimm, "Beeware," airs tonight at 9 ET/PT on NBC.