The irony of resources in low income neighborhoods
One of the features of the novel is the attention MacDonald pays to the difficulties of life in a low income community. Not only is there a scarcity of basic needs in such environments, but also there are serious mental health issues that stem from the difficulty of such a life. This means that the communities who have the least suffer the most with the least hope of all. This should be the other way, right? It would make more sense if most of our resources went to the people who needed it the most, but that's not the picture of Southie that MacDonald portrays.
The irony of victimhood versus guilt
Instead of saying "This is who is at fault," MacDonald just tells the facts about many crimes committed, even some by members of his own family. He portrays each crime with the personal story of the "criminal," and he raises a very interesting question: Are his brothers "criminals," or are they victims of their environment? This is a difficult thing to parse, as the book shows.
The irony of drug usage and addiction
Kathy knows something about life that other people don't. She knows that drugs like Angel Dust can make all the pain of life disappear. The irony of drug addiction is that it's one of the worst possible outcomes in life because of how amazing the drugs feel. To Kathy, the drug likely gave her a sense of hope and positivity which addicted her to it and then ruined her life.
The irony of the hero who leaves
Instead of depicting himself as a hero, MacDonald just focuses on the long list of terrible incidents that ultimately caused him to go on the quest for a better life. This is a heroic quest in the true Campbell-esque sense, since it involves a person leaving behind their normal life to pursue the difficult journey of accessing a new life. When he comes back, he does so with eyes wide open and with a new life's worth of experience with which to discern what the community is in need of. The irony is that he has to 'abandon' the people he loves in order to honor their legacy and carry the torch forward in the pursuit of happiness.
The irony of Whitey's influence
The aspect of the criminal element depicted in the story is complex and reasonable, and it shows a fairly common understanding of the issues. One ironic aspect of Whitey's power in the community is that basically everyone who is not in the gang or buying drugs from the gang feels the same way about Whitey as the author does, and yet, Whitey has more authority over the community than anyone else, because of his army-like gang forces and the power of addiction to ruin a community.
