In an article with New Zealand Stuff, The Hobbit: An Unexpected Journey co-writer Philippa Boyens discussed returning to Middle-Earth, handling various story elements and why they decided to invent a new character for the films.
On returning to Middle-Earth:
When asked, there's a long pause before she answers. "I loved the world. I loved [JRR] Tolkien's writing. [But] I think there was a quality about myself where I felt like 'I'd done it'," she says while in Wellington. "But that feeling didn't last very long because The Hobbit is a whole other fantasy really, a whole other work. Once we got into it and started writing it I felt really good about it and then I started loving it more and more. It was a natural process of falling back in love."
Re-writing after Guillermo del Toro left:
"...we were writing a film that would have been a different Hobbit to what this is. I would have loved to have seen that film because I think he [del Toro] is an incredible film-maker. But once Guillermo made the decision that he couldn't do it and Pete made the decision that he would step up and do it, we had to start again. You need to write for the director, or in this instance, a vision that the director has."
Handling the two "endings" of The Hobbit:
"You don't want to be restarting the story. The death of the dragon has to be part of a bigger whole," Boyens says. "And the story shifts and changes. It starts as a rollicking kids' book. Then if you look at the last few chapters of that story, it gets darker. It does move towards the world of Lord of the Rings. That was always going to be a challenge – that shift in tone."
Juggling the 13 dwarves:
"There are certain things that are sacrosanct and those dwarfs are one of them. And in the end it was a relatively easy solve. It's in the storytelling. I sort of had this eureka moment one day when I realised that it's not about it being too many dwarfs but about there being too few. Once you shape the story and you understand that there's only 13 of them and they are going to try to take back a mountain from a dragon you're off."
On creating Tauriel the Elf for the films:
"This is a decision where you move away from being a Tolkien fan and you have to be a fan of film. It was a fairly easy decision as well because it just gets a little much – the weight of this masculine energy. It is pretty unrelenting. It's in a good way and it's wonderful, the dwarfs remind me of a really good rugby team. They are very staunch, hard dwarfs. We could have introduced a female human character. But we decided on an elf. There was a little story thread in Lord of the Rings that we wanted to pick up on and develop and it involved a very feminine energy, so we decided to use it and the character of Tauriel came into being."