You take up for your buddies no matter what they do. When you're in a gang, you stick up for the members. If you don't […] it isn't aging any more. It's a snarling, distrustful, bickering pack. (2.66)
Pony proves his own point at home. When he and Darry start to lose loyalty for one another, their home becomes a place of argument, anger, and mistrust.