How did Darry act when Ponyboy came home? Why did he act like that?

Darry is relieved and angry at the same time. Acting as Mom and Dad for his two brothers is a difficult task. It also makes him see things differently now that the boys are alone, and he is responsible. After their inital talk, Darry takes Ponyboy to task for his grades, for walking alone, and for not carrying a knife when he's going to walk around alone at night. All in all, he acts like a parent, older brother, and cherished friend all at the same time. And that is because he is in fact all three.