CM: Very much so. To me, he was a blank page: instantly recognizable but a peripheral nursery rhyme character. I wanted to create a character that was definitely an outsider, picked on, on the fringe of his little orphanage, but really smart, and very much a da Vinci mastermind. And a dreamer. At least when he was young, his ambitions were artistic and not destructive. When his dreams didn't come true, greed took over and a sense of entitlement. And that coupled with desperation when it looks like he's losing his one friend in the world. The brotherhood story really drives everything for him. He's very complex: jealousy and resentment and it made for a really compelling character. And he makes some horrific choices: the betrayal. One of the biggest tricks for us was, after he sets Puss up, trying to redeem his character honestly. If that didn't work, I don't think the film works at all.

Kitty Softpaws adds a bit of unpredictability to the story.

BD: The whole thing is predicated on reversal of expectations.

CM: Yes, definitely. Humpty Dumpty isn't as he seems; Jack has a strong maternal streak; and Kitty and Puss are unpredictable.

BD: What was del Toro's biggest contribution?

CM: He loved the film already and followed the path that we were on and supported it. He was really helpful in actions scenes. In particular, there's a great action scene when they're escaping the castle and all the spectacular shots were in there of the landscape, but we couldn't figure out why it was so disconnected. We thought it was really long yet we kept cutting stuff out and it still seemed disconnected. We brought Guillermo in and asked what he thought, and he just looked at it and said we needed to add stuff. You need to add a close-up here; you need to add a character reaction here; you're not with the characters in this world. It didn't feel long anymore -- it felt right. Point of view in a big set piece. You can fall in love with the incredible artwork you've created. He was invaluable in those kinds of situations.

Bill Desowitz is former senior editor of AWN and editor of VFXWorld. He has a new blog, Immersed in Movies (www.billdesowitz.com), and is currently writing a book about the evolution of James Bond from Connery to Craig, scheduled for publication next year, which is the 50th anniversary of the franchise.