Pete's team began designing characters to match the personalities in the storyline. He explains the development process. "The hardest part is getting the story and characters to relate to each other. Carl's an amalgam of our grandfathers and my friend Joe Grant, one of the animators who worked on 'Snow White and the Seven Dwarfs.' Joe wasn't really a grouch, but we drew lots of inspiration from him as well as George Booth cartoons, Ed Asner [who provided Carl's voice], Spencer Tracy, Walter Matthau, and other gruff but lovable old-time actors. Production designer Ricky Nierva drew Carl based on our gut feelings of what we knew of him -- a stuck-in-his-ways kind of guy who just wants to stay put ... and we kept coming back to this square shape."

According to Pete, costume design in animation is an often-overlooked but extremely important factor in developing memorable characters. "There's a lot of work in getting just the right amount of bagginess in the pants while still being able to see Carl's knees. Old folks kind of shrink a little, so the clothes that used to fit now feel a bit oversized ... they're slightly bigger," he says.

Russell was born out of Pete and Bob's collaboration with co-writer Tom McCarthy -- and the little boy's relationship with cranky old Carl truly gives the story its heart. "This is about a guy who's finally rejoining society and we were looking for ways to really get him reconnected. It just seemed like this relentlessly optimistic kid would be the perfect way to do that. We imagined Russell to be kind of round, the opposite of Carl, so we designed him with that in mind. At first they have absolutely nothing in common ... yet both have these empty holes in them that the other has to fill," Pete continues.

As their amazing adventure unfolds, Carl and Russell come across some pretty intriguing animals, like a whimsical "snipe" that's really a rare tropical bird they nickname "Kevin." Dug's a talking retriever who adopts Carl as his master. "Kevin, Dug, and the talking dog pack were designed as another way of luring Carl out of his shell. Kevin represents a surrogate baby that needed to be cared for. Dug is this needy character that desperately wants to belong ... so it's all about an oddball family coming together."

Casting voice actors to bring Carl and company to life wasn't easy but Pete agrees the resulting performances couldn't be better. "We listened to hundreds of voices before agreeing on Ed Asner -- he's gruff yet completely lovable. When Jordan Nagai came in to read for the part [of Russell], he started talking about judo and had this charming innocence to his voice. He's not an actor but his voice was really appealing. And of course, we needed explorer Charles Muntz to be a symbol of vitality and adventure. Christopher Plummer is fantastic ... he's an instinctively strong actor with just the right amount of vigor."

To capture the look and feel of Paradise Falls and its surrounding landscape, the animators visited Angel Falls, Venezuela, to experience it firsthand. "We didn't know where to start, but we found this location -- an island in the sky, completely removed from the rest of the world -- that just seemed to mimic Carl as a character."

One of the toughest technological challenges was the film's most stunning visual – an uprooted house floating through the sky via balloons. Pete adds, "At one point we had 20,000 different balloons all bumping into each other and interacting with the wind as well as the strings that connected them to the house – it was a bit of a challenge."

How does he hope audiences will react? "There are some funny scenes, action, adventure ... but then there's real emotion that speaks to people. The central theme is redefining what adventure really is. Many of us have lofty goals, things we want to do, places we want to visit ... but often we stop paying attention to what ultimately matters. These real-life moments between family and friends are what adventure is really all about," Pete responds.

"Up" promises a hilarious yet heartfelt journey that the whole family will talk about long after leaving the theater!