In one way, Helen and the parents are similar in how they treat Krebs. All of them treat Krebs the way that they treated him before he went off to war; however, this is also the key difference. Helen has always thought the highly of Krebs. He was her heroic big brother before going to war. Now that he's back, he is still that same person to her. She adores him and accepts him for who he is. It doesn't matter to her that he has come back a changed person. She loves him nonetheless, and she wants Krebs in her life.
"We're playing indoor over at school this afternoon," she said. "I'm going to pitch."
"Good," said Krebs. "How's the old wing?"
"I can pitch better than lots of the boys. I tell them all you taught me. The other girls aren't much good."
"Yeah?" said Krebs.
"I tell them all you're my beau. Aren't you my beau, Hare?"
That contrasts sharply with how Krebs's parents treat him. His parents still treat him like the little boy they once had. They nag him about mussing up the paper, and they have to discuss whether or not Krebs can be allowed to borrow the car. They nag him about jobs and girls and all kinds of things. On one hand, this is understandable. He's their son, but Krebs creates distance from them because his parents don't recognize that he has come back a different person. Another possibility is that they don't accept that he has come back a different person. Their nagging and demands have to sound small and petty to Krebs because he is now a man that has gone off to war, operated all kinds of war equipment, taken lives, and seen horrific things. He might be young, but he is absolutely a changed man, yet his parents treat him like the little boy that he was. Helen treats him like the Krebs that he is. Her older brother.