As the Carl and Russell's story progressed, Pete Docter and Bob Peterson were joined by producer Jonas Rivera. The three men shared the film’s visual and stylistic approach of the film, but more important still, they agreed on the emotion and the spirit which had to be brought out in the film. Jonas Rivera explains: “Pete, Bob and I are ardent supporters of Disney movies. We wanted, through certain aspects to return to the essence of the films which the public and we ourselves enjoy. The great Disney classics have truly inspired us. We wanted to find the charm of films like DUMBO, whether in terms of design, the language level, or image structure. These films define themselves by a certain drawing style, a simplicity which makes the subject crystal clear and bright. That's what we looked for. We all worked on UP with the word ‘simplicity of spirit’.” Just the idea of a house hanging from balloons implied the notions of a journey and an adventure at the highest level, but the definition of the characters gives it a sense of affection, emotion and a tremendous potential for humorous situations. The mixture looked surprising…

Pete Docter tells us: “Jonas gave us one of the nicest compliments one can hope for. When he came to see what we had done, he looked at everything, listened to everything and then he told us that it made him want to go back home to be with his wife and hug his children. If that's the effect this film has on people, if by sharing this story they rediscover the happiness in living and the chance they have to be with their loved ones, then we shall have succeeded beyond everything we hoped for.”

The film is an exotic alliance between a unique universe and uncommon characters. To give them life coherently in a manner which does justice to the project's spirit, the creators had to define a visual style unlike any other. Producer Jonas Rivera explains: “Pete often takes an emotional approach to things and by working together we tried hard to express it concretely. He is never afraid of taking his ideas to the limit, not to undergo the extreme but in order to make sure he hasn't missed the core of what he wants to say. Since we're dealing with a flying house attached to thousands of balloons, there were at the same time poetic and realistic components which had to respond to each other through a precise balance. The film also speaks about memories, nostalgia, and all that makes up a rather particular universe and tone. To create UP's world, we could not use what had already been made. We had to reinvent how people were represented, their clothes, hair, water or any other element of the story. We had to define a graphic style in harmony with our subject for this fable and adventure. Our approach defined itself by looking for the real heart or for the dominant feature of each of its elements, which isn't very common for a caricature.”

The personality of the characters did not escape this rule. Bob Peterson confides: “For Carl's character, for example, I remembered my Irish grandfather. He liked telling us stories. He had been raised in the countryside of Ohio and he had thousands of anecdotes about his life on the farm or school during that time. His stories stood out to me and sustained me. They are like references for me. I adored my grandparents and what they passed on to me has given birth to some beautiful ideas.”