Chance is a young, immature American bulldog owned by a young boy named Jamie who cares for him very deeply. Given his early life, he was abandoned as a puppy and sent to the pound. Fortunately, he was adopted by Jamie and given a home. His pet comrades are Shadow, a wise, old golden retriever and Sassy, a Himalayan cat who is constantly annoyed by Chance's antics and is usually tortured by him. During Bob and Laura Seaver's wedding, he ended up eating the wedding cake before the newlyweds could cut it, which eventually ended up working against him where it gave him indigestion and forced him to vomit up what was left of it after launching Sassy into the sandbox. Due to his immaturity, Chance has a tendency to get himself (as well as his pet comrades) in trouble. He considers Shadow an old fusspot and calls him "old timer", but still has respect for him. His fear of going to "the bad place", AKA the pound, seen in the second film leads him and the others to be left behind. The second film also implies he has a bit of a paranoid nature to him, as he vomited up a green kibble (implied to be a sedative) due to thinking the owners were going to do something bad to him and the other pets.
Chance with Shadow and Sassy in Homeward Bound: The Incredible Journey
Chance in Homeward Bound II: Lost in San Francisco
Chance lounging about
Chance leaping at Kate in attempt to take Shadow's dog bowl for himself.
Chance stealing and eating Sassy's food
Chance foolishly returning to the airport lobby, resulting in him and the others getting left behind
In Homeward Bound II: Lost in San Francisco, even though Chance is still called an American bulldog, he was actually portrayed by an American Pit Bull Terrier. This is apparent in that in the first movie, Chance's face was more mushed in, whereas in the sequel, his face was stretched out. American bulldogs have mushed-in faces, while pit bull terriers do not.