When not chomping at the bit for "Underworld: Evolution" to finally land in theaters on January 20, die-hard fans of the vampire (or Death Dealer) and werewolf (or Lycan) thriller spend a lot of time debating the seemingly ambiguous rules of the "Underworld" universe. Here, writer/director Len Wiseman and leading lady (and real-world wife) Kate Beckinsale shed light on some of the films' murkier details, including who, exactly, is evolving, what happens when hybrids gnaw on one another and why focusing on furry women might be too frightening for even hardcore fans.

MTV: Do the film's immortals age physically?

Len Wiseman: No, they're immortal in the traditional sense. They stop aging once they become immortal. Selene became immortal when she was bitten, and she was as we see her. The elders were older when they became immortal.

MTV: How old was Selene when she was bitten?

Kate Beckinsale: She was, I suppose, in her early 20s, so I related to her very well.

MTV: Is the Corvinus family responsible for the creation of both the Lycan and Death Dealer armies?

Wiseman: Yes. The original source was Alexander Corvinus (Derek Jacobi), who possessed a special [trait or genetic makeup] that spawned the first vampire and the first werewolf. Michael (Scott Speedman) was the human strain of that bloodline.

MTV: Since Selene bit Michael [in the first film], does he have all her memories?

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Wiseman: Yes.

MTV: If Michael now has Selene's memories, and Selene was originally bitten by Lucian (Michael Sheen), does Michael have Lucian's memories, too?

Beckinsale: You get much more adept at controlling the genetic memories as you go along. Michael has Lucian's memories, but it's much harder for him to sort of rifle through that Rolodex and really know how to access all of them. There are other people in the movie with Lucian's memories who can access them much faster. Michael is a bit glitchy and slow.

Wiseman: Michael started to get Lucian's memories in the first one, and he continues to have those [in the sequel].

MTV: So if a vampire bit five people, the sixth would have all five of those peoples' memories?

Wiseman: They do, although what we're establishing is that not everybody has the capability to really file these things away and has the ability to use these memories the right way. You know, it's only the elders who have the capacity to make this memory thing work. With the younger ones, it can get a bit more chaotic. It's kind of like shuffling through a DVD but knowing exactly when to press "pause" and when to press "play." But the older and the more powerful you are, like Viktor (Bill Nighy) and Marcus (Tony Curran), you're able to file these things away and access them in a heartbeat.

MTV: These vampires break some traditional rules — they can see their reflections, they aren't afraid of crosses. Why?

Wiseman: It's just my personal taste, really. I feel like there are realistic vampires and there are fantasy vampires, and I could never understand or get my head around a vampire who cowers at a cross or at a bunch of garlic. I know I get slammed for it all the time, but I like to approach things as realistically as possible, and if I treat it more like it's a genetic anomaly or something that just happens in the blood, then it seems a bit more grounded for me.

MTV: Could Michael start his own army and create other hybrids by biting them?

Wiseman: If Michael got hold of somebody who had the same bloodline of the Alexander Corvinus strain, he absolutely could. But only those in the family line have the ability to turn into a hybrid.

MTV: So if Michael bit an average guy, that guy would just drop dead from the conflicting blood entering his body?

Wiseman: Possibly. Michael hasn't done that yet. That's an interesting question.

MTV: When Selene bit Michael in the first one, did she get any of his blood?

Wiseman: She didn't get his blood.

MTV: If she had taken in his blood, would that turn her into a hybrid?

Wiseman: There's a lot of speculation about what Selene could become. You have to have the right genetic makeup to actually be able to house the blood of a vampire and the blood of a werewolf and not die. It's established in the first movie that most people die if they're bitten by both [a werewolf and a vampire]. But because of Michael's lineage, he has the genetic makeup that allows [him to absorb] the two. That's why he was so special in the first film.

MTV: Lots of fans suspect that when Marcus wakes up, he'll be ticked off that he's a hybrid.

Wiseman: We'll just have to find out. All I can say is that some fans are right on the mark, and they know what's going on. The ones that really dialed in to every word of what's said in the first one, some of them are getting quite close.

MTV: Are you thinking about a third movie?

Wiseman: We are. There's been a lot of talk about doing a prequel, as well, because there's a lot of history I was dying to tell in the first one and that I'm trying to squeeze into this one. Bring back Bill [Nighy], bring back Lucian and Alexander Corvinus and William, the other brother, and there's a lot still to be told. So [the idea of a prequel] has been tossed around, as well as talk of a third one.

MTV: The title, "Underworld: Evolution." Who, exactly, is evolving?

Wiseman: That would be Selene.

MTV: The first movie said that both sides of the war could have offspring. But why don't we ever see any kids? Why don't we see Lycan women?

Beckinsale: Because that could be really horrifying. Hairy, thuggish women.

Wiseman: And you don't actually want to see little furry children. I've seen furry women.

Beckinsale: [Laughing] Not here!

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Check out everything we've got on "Underworld: Evolution."

"Underworld: Evolution: Inside The Action" premieres Tuesday, January 17, at 8 p.m. ET. Tune in and see how the moviemakers created the film's amazing stunts.

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