I wish I could remember the name but I remember reading a book for a class in high school where the first 2 chapters follows a pair of protagonists as they travel together, and they basically keep telling each other how important it is to always help people and fight injustice, and right at the end of the second chapter they get to the city they've been traveling to and they're so hopeful that they're going to make it a better place. And then the start of chapter 3 skips like a year forward and one of the characters is working at a clinic and lives in the slums, while the other is an enforcer for a mob boss/slave trader and living in a rich neighborhood.

I remember a classmate insisting that the author was promoting being a terrible person because the good character had a hard life and the bad character was living easy, and would not accept the idea that the author was exploring how people are willing to abandon their stated ideals if doing so will guarantee them comfort and luxury. It's been over 15 years since I've read it but I remember the character living in the slums having a pretty good time throughout the book despite living surrounded by poverty. Meanwhile the book the mob enforcer character literally burns to death from the inside while all of his "friends" just watch and refuse to help him, symbolizing how his greed has destroyed him.