Siblings are expected to stand up for each other.
Even though both Gary and his brother both drew on the walls, their mom only yelled at Gary's brother.
Gary wants to decide what to do.
Gary steps in and tells his mom that he was involved as well.
Gary doesn't get involved and ignores his brother for the rest of the day.
Gary's brother is glad that Gary took some of the heat away from him.
Gary's brother feels betrayed and loses his trust in Gary.