Kirby is the lead dog (or so it would seem) of Mr. Simpson's mail team. He appears to be a wise dog, though he has his moments where he falters. He, along with his team mates, also dislikes Duke and his plane. Even suggesting the plane may have crashed doesn't concern them. They just boast about how dogs are "tough and reliable", and that he was trying to steal their jobs. However, Kodi, after having a conversation with Jenna, was able to knock some sense into team mates about helping others.