Unlike some authors that sign away the film rights and then are left out of the movie making process, author Cassandra Clare is an active participant in bringing The Mortal Instruments: City of Bones to life on movie screens.  She explains that it started during casting:

"I called Constantin (the production company) and asked if I could talk to the casting director.  They gave me her number and we got really close, so we would talk about casting and then we would talk with Harold the director about it, and then [producer] Robert (Kulzer) would weigh in so that everything became a group decision."

During a group interview on set last year, Clare also talked about how the book originally got optioned, making sure key moments from the book made it on screen, her reaction seeing Jaime Campbell Bower and Lily Collins at the auditions, her relationship with the fans, and so much more.  Hit the jump to either read or listen to what she had to say.

Before getting to the interview, here's the official synopsis and trailer:

The Mortal Instruments is a series of six young adult fantasy books written by Cassandra Clare. In the series’ first book, the #1 New York Times bestseller The Mortal Instruments: City of Bones, set in contemporary New York City, a seemingly ordinary teenager, Clary Fray, discovers she is the descendant of a line of Shadowhunters, a secret cadre of young half-angel warriors locked in an ancient battle to protect our world from demons. After the disappearance of her mother, Clary must join forces with a group of Shadowhunters, who introduce her to a dangerous alternate New York called Downworld, filled with demons, warlocks, vampires, werewolves and other deadly creatures.

As usual, I'm offering you two ways to get the interview: you can either click here for the audio, or the full transcript is below.  The Mortal Instruments: City of Bones opens August 23.

Question: So what's it like for you to finally be on the set of this film being made?

CASSANDRA CLARE: It's my second set visit but it's amazing to see it come to life like this.  The sets are really beautiful. They are very intricate.  Hopefully you'll see them when we go out and tour the set, but they really recreated these sort of imaginary places with incredible attention to detail.  There’s a place in the books called The City of Bones that...the books are named after that...the underground city is built out of human bones and corpses and I think they made 1,000 or 2,000 different models of skulls and each one is different aged to look differently, each one has different sort of features and has been changed in a different way so even though you probably only see it in a glancing shot in the movie, I know every single one of those is different and I think it adds incredible texture to the film.

What was your initial reaction when you were approached regarding optioning your book into a film?

CLARE: I thought a lot of things get optioned all the time and they rarely ever get made, so I thought, "Well, okay, it's wonderful that someone likes these books so much that they want to option them," and it was originally an option project by Unique Features, which is Michael Lynne and Bob Shaye, who executive produced Lord of the Rings, which are my favorite fantasy series, so I thought, if you're going to sell your fantasy series to someone, who’s a more trustworthy bunch of people than them? So I thought, "Well, I'm happy to option it to these particular people;  probably nothing will ever happen."

When it started to really ramp up did you make a point to really be involved in the process? How did that work?

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CLARE: It was sort of organic. They brought in Constantin as a co-producer and to help fund the film, and then when we started to get into casting with Sony being our North American distributor and Constantin and Unique Features, there were a lot of voices, but I called Constantin and asked if I could talk to the casting director and I thought later maybe no one ever told them that they were supposed to tell me, "No, no you can't talk to the casting director because why should you?" but they were like, "Sure, you can talk to the casting director," and they gave me her number and we got really close so we would talk about casting and then we would talk with Harald the director about it and then Robert would weigh in so that everything became a group decision and I don’t know if that was ever an official policy that they adapted or if it just kind of grew organically out of the fact that from the beginning I assumed, surely, "Of course you'd want my opinion, why wouldn’t you want my opinion?" and they never...possibly because they have never done a book adaptation before...never got the memo that you're not supposed to include the writer.

When you wrote these six books, obviously you have a vision of what these characters look like. So when they started casting, what was your impression?  Were there moments where you were like, "Oh, that's interesting." or did it make sense to you when you started to see who was being cast?

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CLARE: I don’t know if this is the case for all writers, but certainly I have a very clear vision of what these people look like in my mind and what I did not expect was for them to reproduce that vision exactly, because there's no way you possibly can.  What I wanted was something that felt more organic, that we were going to kind of get people who somehow embodied the spirit or captured the essence of that character and that mattered more to me than whether their eye color was the correct eye color or their height was the correct height and I think we managed to do that.  Robbie Sheehan has that playful spirit that Simon has and I felt that he is such a good physical comedian and was so funny that he would be able to bring that to the role.  Jared Harris is so wonderful at playing conflicting characters that I felt that he would be a great Hodge.  He doesn’t look exactly like the character described in the book, but that doesn’t matter to me as much as the fact that I feel that he can really pull that off.  The only stipulation  that I ever made was that the character Magnus is Asian in the books and they must cast an Asian actor.  

Your book is like 500 pages. Obviously when you're adapting something, you're never going to get all the stuff from the book into the movie.  Can you talk about certain sequences that they wanted to cut out that you were like, "Oh no, this has to be in the movie."

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CLARE: It was always an issue of back story, it was never an issue of the actual sequence of events in the book.  There is always a balance between...the way you can convey a back story in the book is so different then the way you can convey it in a movie and indeed in a movie it is very difficult to have a character standing there and just talk and talk and talk for half an hour and have that be interesting and dynamic, so that was always the issue with Harald where we'd go back and forth and I would say, "This fact is very important and it somehow needs to be incorporated," and he would say, "Well how do we incorporate it dynamically?"  One of the most important ones was a particular thing about the past of one of the characters, Jace, and I felt there was a very significant thing about his back story and his childhood that we needed to get across and we kind of went back and forth about how we were going to get it in and then Harald decided to do it as a flashback, as a silent kind of flashback that has no words in it and I think it's going to be a really great way of getting that across. There is a visual shorthand that you can use in movies that you can’t use in books, everything has to be described, but with a movie you can use a repeating visual motif and I think coming to those kind of agreements about how "this is how we are going to convey this" was an interesting part of the process.

How do you feel Lily Collins has embodied the role of Clary Fray?

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CLARE: Lily is an interesting one because Lily is the only one I didn’t have anything to do with casting.  She was attached to the project really early on which was really great for us because she had just been in The Blind Side and before she had done a lot of work so we were lucky to get her.  I think that Lily, from watching her be Clary, she's been a fan of the books for a long time which I think is really helpful because she sort of admires Clary and she relates to her and I think that she brings to the character a grounded relatability to that character.  She's a real character, she likes Munga, she loves her nerdy music, she has her room that's covered with her favorite band posters and her sketches; you really feel that she's grounded in the reality of this girl who also discovers that she can be this warrior.  

What were your feelings when you first say Jaime and Lily together at the audition?

CLARE: It was really embarrassing.  I cried.  I was so happy.  We had been looking for Jace.  It was an ordeal process. Every young blond actor in Hollywood tried out and Lily, bless her soul, went in over and over for chemistry reads with people and Jace is a tough character.  He is a guy who covers up his vulnerability and is real personality with a lot of layers of just being a jerk and if you play him wrong he'll just come out as a jerk, but if you play him right he comes across as, "I'll use my wit to hide my broken heart and my pain and I’m vulnerable and love me."  Nobody was quite hitting that, so Lily did all these chemistry reads with all these different people and I was starting to think, "Maybe no one can play this role, maybe I have written a bizarre character that cannot be played," and then Jaime came in and he had come in off a long flight from London and literally just came straight in to the studio in his jeans and shirt and he auditioned with Lily and it was amazing.

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He knocked it out of the park, he was terrific. He was funny when he needed to be funny, he was vulnerable when he needed to be vulnerable and he got across all of the layers of what was going on with the character pretty effortlessly and I could tell.  Sony called me up and told me they were going to send me an audition tape and it's Jamie Campbell Bower and I thought, "Oh, the little guy from Sweeny Todd...really?" and they said, "Don’t make any assumptions, that was many years ago, just watch it," and I said, "I'll watch it with an open mind," so I started watching it and I was sitting there as they were just reading off literally the dialogue from the books and I just started to cry because I was like, "Those are my characters."  It was perfect.  So from then on, I was completely cemented with "I love Jamie" and didn’t want anybody else.

There was a little confusion as to what scene Lily and Jaime auditioned with?

CLARE: It was a set of scenes.  I hope I'm not getting this wrong, but I believe it's the first time they talk and he sort of explains what a shadow hunter is, then it was a romantic scene and then it was a scene in which they fight.  We were just trying to display the range of chemistry they can have.

Just seeing the immense machinery involved with doing a big production like this, does it give you a newfound appreciation for just doing the solo work that you do as a novelist?

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CLARE: It's an exercise in learning to let go, to a certain extent.  Part of it is amazing to see this huge machinery at work that's all focused on something that you created because writing a book is probably the most solo kind of artwork that I can think of.  You write the book and it basically comes from you unchanged into the world, untouched by anybody else, where a movie is completely a group project and I do come in here and I see them making paintings and I see them building sets and I keep wanting to thank them for doing all this.  This is a huge favor to me in which you build these beautiful sets, and beautiful people come and act scenes from my books and then I remind myself that this isn’t actually about me in any way.  It is a bit of an exercise in letting go.  There are my books and they're here and they are the thing that I control and then this is a movie and this is an artistic interpretation of my books and that's the director's vision and the actors' vision and they have to do what they think is right.

What have the fans been most vocal with you about in terms of wanting to find out about the movies or questions that they really want to know?

CLARE: There are a lot of questions and I have a really close relationship with my fans in terms of social networking: I tweet, I have tumbler, I have Facebook, so we are pretty interactive.  There's a lot of stuff I can't tell them.  A lot of it is, "Is my favorite scene going to be in the movie?" and it's always a different scene.  Sometimes the answer is "Yes" sometimes the answer is "No," but I can’t tell them because: A) I can’t tell them what's in the movie, and B) a movie is not done until it's edited, so a scene could be filmed but that doesn’t necessarily mean it's going to be in the movie or it could not be filmed but they come back and do a re-shoot and can be added in later, so a movie in progress...I can’t give you an answer like that, so mostly what they want to know: "Is my favorite scene going to be in there?  Is my favorite character going to be in there?" and they want to know what the actors are going to look like, are they going to dye their hair, are they going to wear contacts, what are their costumes going to look like, that kind of thing. 

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The producers mentioned that they actually looked to the fan communities to see how they visualized the characters in the world.  How big a part would you say the fan base has played in actually having some amount of creative input in this?

CLARE: I think they've had a significant amount of input.  They really scoured the internet especially for fan art, they really wanted to see how fans visualized the world and kind of see the repeating motifs over and over because there are things in the book that are never really described.  We know they exist, such as the gear that the Shadow Hunters wear to fight in.  I never really describe what it looks like, so one of the things that they did was go to the fan art and look for the repeating idea of how fans imagined that fighting gear might look and I think that served as a kind of template for their eventual development of the gear.

Have there been negative interactions with fans?

CLARE: When a movie is being made out of a book, there is a mixed reaction on the part of fans because they are both extremely excited and they are also terrified.  They are going to take my story and they are going to mess it up, they are going to ruin it, they're going to do this, they're going to do that.  When you have people who have passionate feelings, every piece of casting is a contentious piece of news they are going to get together and they are going to fight about, but I feel like that is a thing that really is another exercise in letting go.  One, you put books out into the world and people form their own visuals and images and attachments to characters, those characters become part of them and they have their feelings about them.  You kind of have to let them have their feelings and let them have that fight because they don’t know how it's going to turn out and the only way they can kind of reassure themselves is to engage in this exercise of talking and arguing.  As a book fan myself who's watched books that I love be turned into movies, I know that experience and I think it’s just something you have to let people do and eventually they'll see the movie and that'll make their judgment.

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Was there a moment where it just clicked, and you felt sure that this was the right way to go?

CLARE: When I first saw the dailies.  Robert Kulzer, the producer, was really excited about one of the scenes.  It was a scene with Jace and Clary, their big romantic scene that happens in a greenhouse and they’d just got the dailies back and he came running over to me and said, “You have to see this,” so we watched it.  It was really beautiful.  I thought that Harald did a wonderful job capturing this lush urban fairy tale look and I said, "How gorgeous!"  That’s exactly how I pictured it and I felt it did for me, at least seeing that scene, I felt confident that if he could handle that scene so well, I feel confident that he’ll be able to handle the rest of it too.  And Robert was clutching his iPad to his chest he said, “I’m a producer, my heart is cold and dead, but even I love this scene.”  I thought that said something.

The first book came out a couple years ago, but how long has Clary been a character for you?  I was wondering, your name is kind of similar...was she something that you were thinking about from the time you were 15 on or was it closer to when you wrote the book or was she more of an amalgamation of everything you wanted to see in a female character. Is there a little bit of yourself in Clary?

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CLARE: I think there’s probably a bit of ourselves in every character.  Actually, I’m much more like Simon; he’s the character to be written more like me.  Clary...Clare is my grandmother’s middle name and it was the county in Ireland that she was from so that’s why I picked it as a pen name.  I think Clary was a bit of a tribute to her; she died not that long before I started the book.  She was a small, fiery, red-headed Irish woman, really brave with a bad temper so I think there was a lot of visualization with my grandmother in there.  I wanted Clary to be a relatable girl.  You know that I had heard so many times people say things like, "You could never write Harry Potter and have it be about Harriett Potter because nobody would read it, people only want to read and adventure story if it’s about a boy," and I thought, “I don’t think that’s true. I think better of girls and I think better of boys and I think they would want to read an adventure coming-of-age heroic drama about a girl and that that would be fine," so I wanted to give her the characteristics that are often associated with boy heroes like Percy Jackson variety.  I wanted to make her really brave and give her a certain amount of recklessness and heedlessness and lack of judgment and throwing herself into adventure and not worrying about getting hurt, but also ground her in the ordinary teenage girl concerns that she has every once in a while: Am I a talented artist? Do I look pretty? Is it a problem that I’ve missed a lot of school?

When you’ve been on set, has any of the cast come to you for inside info on their characters?

CLARE: Sometimes they come and ask. I try to be really careful about not ever going over to them and giving them any advice, I feel they have to follow their own star, but sometimes Lily will ask questions about Clary.  The series isn’t finished so what they’ll often ask about is what happens to their character, how it finishes up, do I die? That was Kevin.  He was like, “I’m going to die right? My character dies, I’m pretty sure I’m going to die, I’m going to get it.” And I was like, “I’m not going to tell you” (laughs) I was like, “Look, none of us know if we’re going to die, so I’m not going to tell you.” Sometimes I’ll tell them things that are relevant to their characters that are either part of my notes that didn’t make it into the book or something that happens in a book that’s not out yet, but I don’t tell them if they’re going to die.

We were talking about how they aged Clary a bit for this movie, so we were asking the producers what they thought about that and did that make sense to you, did you have to change anything for her story or her journey because she was a little bit older?

CLARE: We went back and forth on it actually.  They did want to age Clary for a couple different reasons and I understood their reasons, but I also didn’t want to age her out of the phase in which I thought it made sense for her to be going on this coming-of-age journey.  Once you have aged someone past the point that they have already come of age, you can no longer tell a coming-of-age story, so what we basically agreed on was making her a bit older than she was in the books, which I was fine with aging her up from 15 which is quite young and kind of leaving it open to interpretation to a certain extent how old she is exactly.  Her definitive age is never mentioned.  I felt that was the compromise that we came to in the sense that, if you’re watching the books, you can read into it to a certain extent how old that you feel that she is.

For more from our Mortal Instruments set visit: