Quote 1
"I was sorry that his had happened to the old man. He was the only person who had ever been good to me after my mother died." (5.63)
Peter—like Alex—had his life saved by an unlikely father figure. He was saved from the streets by Jacob the Baker, who sheltered him, protected him, and taught him how to be a good man. Given this, it's only right that Peter pays it forward by doing the same for Alex.
Quote 2
"Here, at least, if we are hungry, cold, and filthy, we are those things while we are free," Peter had said. "We are alive and we are free." (6.96)
Hey, that's more than you could say about most Russian citizens. Peter has spent his entire life being abused by people who are more powerful than him, which makes him even more appreciative of what little freedom he's able to carve out for himself and his friends.
Quote 3
"And while you're at it," Peter shouted, "tell him that if he sends me to the police, I will tell the commissars a thing or two that he has done now and in the past." (10.40)
Although the book never says it directly, we're pretty sure Peter is implying that the director abuses the boys at his orphanage. We don't need to delve into the details of this potential abuse, but we think it's worth mentioning as yet another example of how power can be used for evil. This one is especially heartbreaking, though.