Arliss is only five years old, and, in Travis's estimation at least, "doesn't know much". He is uninhibited - he does not try to keep from crying when his father leaves, and thinks nothing of running around naked when Travis threatens to "whale him" for playing in the drinking water. Arliss is a noisy child who always seems to be screaming and hollering about something. When Travis takes him hunting, he knows he is not likely to catch game very easily because of all the commotion his little brother always makes. Arliss, like any young child, can also be annoying, and needs to be protected. When Travis is chopping wood, he knows that his brother will be standing "in exactly the right place for the chips from (his) axe to fly up and maybe knock his eyeballs out". Finally, Arliss is feisty. He does not hesitate to defy his older brother at every opportunity, and when he is angry, as he is when Travis kicks Old Yeller, he takes a battling stick and comes after Travis swinging.
Papa is "tall and straight and handsome". He sits high and straight in the saddle, and wears a high-crowned hat and a black mustache "drooping in cow-horn curves past the corners of his mouth". He is a good parent who gently tries to instill a sense of responsibility in his older son. Papa is hard-working and practical, braving the rigors of a six-hundred mile trip on horseback to sell cattle to make money for the family, and he is strong and hardy enough to endure the demanding undertaking. When Papa returns home and discovers what has happened to Travis in his absence, he shows that he is also wise, knowing what words to use to help his son to carry on.
Mama is a strong woman, the quintessential pioneer woman who has what it takes to survive on the farm with her two boys for months while her husband is away. She loves beauty, having chosen the place where the family built their home because "it was all so pretty and smelled so good and the singing birds made such fine music". Mama is stubborn; there was no question but that Papa would build the house at the location she chose once she made up her mind. She also tries to be fair and reasonable, insisting that Arliss be allowed to keep Old Yeller because he is lonely, and because Travis also had a dog when he was Arliss's age. Finally, Mama is capable and resilient; she always seems to know what to do when disaster and the unexpected strike when she and her sons are left on their homestead alone.