Shaun Mars is the second son of Ethan and Grace Mars, and the younger brother of Jason Mars. After the death of his older brother, his parents divorced and now have joint custody over him. Shaun appears disconnected from his father and other people in general. He seems melancholy, preferring to watch TV rather than talk to or play with his father. He also does not take the initiative to play on the playground, whether it be playing by himself, with other children, or with his father. If Ethan instigates the playtime, Shaun will likely join in and enjoy himself. Shaun frequently mentions his brother Jason, and how he wishes his life was still the same as it was when Jason was alive.