News flash: The same writer who gave Dexter its shocking season finale is also the one responsible for the swoons you'll hear coming from theaters on June 30, the day that The Twilight Saga: Eclipse opens across the globe. That's right -- serial killers and sparkly vampires both live in the mind of Melissa Rosenberg, who's scripted all three Twilight films to date (and is currently writing the two-part Breaking Dawn films to close out the franchise).

Rosenberg worked closely with novel author Stephenie Meyer to adapt the third book, Eclipse, in which Bella Swan (Kristen Stewart) finds herself torn between Edward (Robert Pattinson) and Jacob (Taylor Lautner) as a vicious army of vampires led by Victoria (Bryce Dallas Howard) comes to kill her. With the threat of Victoria and her protégé, Riley (Xavier Samuel) looming overhead, plus horrific flashbacks to Jasper and Rosalie's origins and a number of head-ripping fight sequences, Eclipse is by far the darkest film in the saga thus far.

I caught up with Rosenberg to discuss her work on Eclipse and the impact that critics, fans, and Stephenie Meyer herself had on the ways the film differs from the book. She also shared her thoughts on where to split Breaking Dawn into two films, how she intends to stay true to the novel's gory details, and -- oh yes -- I made sure to champion the grassroots Twi-hard campaign to see lots and lots of feathers. (Read my previous New Moon chat with Rosenberg here.

One of the additions to the movie that wasn't necessarily in the book was Bella's big "I'm confident!" speech at the end. How important was it to include a scene like that in the film?

You're the first person to notice that! The character of Bella in the movies, and as portrayed by Kristen, has taken on a life of her own in certain ways. She's a strong character, so it was about really being true to the character as it developed in the movies. She just struck me as someone for whom that would be true. It goes to the bigger theme of the movie; it's not just a choice between Jacob and Edward, it's about her choosing who she is, what kind of life she wants to lead. So it was really about addressing the bigger themes and staying true to the character of Bella as she has evolved in these films.

You've now written three full films in the franchise; how much has each script responded to critiques, from fans and/or critics, of the previous films?

I'm not sure; everybody who's involved in them, we really try to do our best to stay true to the book. There are going to be some people who don't like that and some people who do, and if you start responding to the people who don't like it you start pissing off the people who did. So you have to be true to your own creative instincts for what works and what doesn't. If people ignored the movie and boycotted it coming in and it didn't do well, then I think we would be listening. But the movies have done tremendously, so obviously somebody likes them! So we keep going with our gut.

Eclipse really ramps up the action from the previous two films -- it's darker, what with all these vampires going a-killin' and coming after Bella. When you were writing the script, how much did elements of horror factor into your vision?

They factor in a lot. The books have horror elements in them, so a lot of time for me it was threading those through from the beginning. The book lends itself to really building a suspenseful situation, keeping the threat hanging over the entire time. So it was kind of fun going down that path.

How early on did Stephenie share with you the events and character details that made it into her new Twilight novella, The Short Second Life of Bree Tanner?

It would have been in the outline stage. I knew from the beginning that I wanted to introduce Riley; that was one of my first ideas: let's open on Riley and how he was created. Coming up with a back story for him and all of that. I think I had probably finished a draft of the outline, it was somewhere around then, and I was asking [Stephenie] about what the newborns were up to -- what was going on for them while Bella's living her life, because they're living it simultaneously? And that's when she shared it with me and I was really able to fill out some of their activities and how Riley was directing them. So it was right there in the beginning.

I read it the other weekend, because I'm a nerd --

[Laughs] You and me both!

In reading the novella, I learned so many new things about vampire science in Twilight, like how vampires re-attach their limbs -- who knew?

Exactly! I didn't until I read that. And the underwater stuff -- in the movie, there's this great sequence where the newborns come out of the water; that was her visual, absolutely. I was trying to figure out, okay so these vampires are coming after the Cullens -- how do they get there, do they take a boat, or they fly? And she's like, 'No, man…' That was her visual right from the beginning.

It struck me that perhaps because of the timing of your writing the script and Stephenie finishing the novella, that you included events from Bree Tanner but tweaked them a bit -- for example, in the movie Riley is more present, but Victoria and the Volturi's motivations aren't explained as clearly. How does that change the idea of authorship, where you're writing scenes that didn't necessarily happen in Stephenie's books?

I guess I'm more attuned to Stephenie's mythology as we go through, so I feel more confident to invent in her world. I'm always very cautious about not violating her mythology, and I think that's the most important thing; when you're talking about sci-fi/fantasy stories, the rules of that world have to be very solid and very intricate and very well designed, and Stephenie has done that. That is her genius. I now have a much better sense of what the boundaries of that world are, so within that world I can be let loose. She gave me permission, and I think I gave myself permission, to do that, moreso in this book than any of the others. That said, it was always very important to me to stay true to the book, so there was a little bit of give and take, but it just sort of lent itself to a little more expansion. It was very much a dance between her and I.

You two seem so collaborative at this point.

You know, it's a blessing. She could be one of those writers who's like, 'It has to be this way, this is the way I saw it,' and she's not at all. She's not precious about it. As long as it's not violating the franchise, violating the characters and the mythology, she's really open. She's just a really great creative partner. It's great having another writer to bounce stuff around with.

Jumping forward to Breaking Dawn, where are you in the scripting stage now?

Deep in the center. Kind of right in the first draft mode, dead center in the middle I'd say. Of both [parts]. I'm kind of writing them simultaneously -- writing both outlines and then writing both first drafts because we're shooting them together. [The producers] need things to prep off of, because they have to find locations, so in some ways I've been treating it as one film, but on two different pieces of paper. It's a huge challenge. It's a lot of pages!

Where exactly do you envision splitting Breaking Dawn into two parts?

We're still talking about specifically where, but I think there's kind of a natural break. You have the first half about Bella being human and a newlywed and pregnant, and the second half is about her being a vampire and a parent. I think somewhere in that transition is where it breaks. We've tried a couple of things and I think we're settling on one, [but] we're not sure.

You and I spoke before about how you stay true to the gory events of Breaking Dawn without going beyond a PG-13 rating. Is that any more of an issue, now that you're writing it?

You know, I just don't find that to be a challenge at all, honestly. I worked on Dexter, and I've said that pint for pint, there's more blood on CSI than there is on Dexter, and yet Dexter is far more disturbing. So I think it's not about how much gore you see on screen, it's more about, are you conveying the terror of the scene, the physical pain of the scene? The tension of the scene? I don't think you need to see gore to know what's going on, and in some ways I think that's actually more interesting. And I think that's true for sex as well. I think the hottest sex scenes I've ever seen are more suggestive than they are graphic. So I don't have an issue with it; I think we can do absolutely everything without having to see specific things.

Just so you know, certain fans of age would like to see lots of pillow-biting and feathers…

[Laughs] Okay! I think they may see some feathers. They may, indeed, see a few feathers.

Check back for more exclusive interviews from The Twilight Saga: Eclipse this week!