When we speak of "compassion," it is clear that this is a reflection of the boy's conscience. This conscience is what understands the need to be "the good guys" and is rooted in his compassion towards others.
The boy's conscience is interwoven within his character throughout his narrative. McCarthy creates the compassion within the boy as a part of his identity. It is difficult to find "one quote" because nearly everything the boy says is a reflection of his compassion. There are moments when his compassion is a reminder to the father of what he wants to teach his son, such as when the boy says to his father, "And we always will be [the good guys]." The boy seeks to be more than what the world around him is. While the father might on occasion become overcome with the savage brutality that exists, the boy's compassion is evident in how he envisions himself and his father as "the good guys."
Throughout the narrative, there are instances where the boy's compassion is directed towards the sad people they encounter. When the man and boy encounter a dead child, this becomes evident:
The boy shook his head. Oh Papa, he said. He turned and looked again. What the boy had seen was a charred human infant headless and gutted and blackening on the spit.... He bent and picked the boy up and started for the road with him, holding him close... I’m sorry, he whispered. I’m sorry.
The boy's compassion is on display here. He recognizes that he could have been this infant. The boy's compassion extends to a stranger, something that leaves an impression on him. To apologize is a reflection of the boy's compassion. He is struck by the level of human suffering around him, another instance of his compassion. In other instances, the boy implores his father to take other forlorn children with them, saying that "I'd give that little boy half of my food." These moments represent the compassion that the boy displays. The boy's compassion which is continually articulated is a reminder of how seriously the boy takes the belief that he and his father represent "the good guys."