The "Gangster" as a symbol for the father's qualities
The father in the novel is not the true father, and the artist makes that perfectly clear by focusing constant attention to the difficult tension between the two of them. Notice how many nights she stays beside him, a silent companion in the wars he was still fighting within himself. Even though the trials of life reduced him to a fraction of his potential, she still sees him for the fighter that he is, and by finding her center, she finds those "Gangster" qualities within herself as well.
Water as a symbol for death
Water is the fundamental symbol in most literature, even the Bible. Basically, the vastness of water, and the depth and obscurity of it, combined with the fact that most humans live near a body of water, mean that for basically our entire history on the earth, water has meant something like, "The Unknown." In this novel, that basic imagery is used as a metaphor for death and oblivion. When she learns about her brother's death in Vietnam, the narrator calls our attention to the image of him emerging from the water. That small resurrection is on account of her learning about his death, reviving his legacy from the silence he became during her childhood—her parents never really talked her through it. One day she suddenly realized that she hadn't seen him in a long time, and that he must be dead. When she finally learns the specifics, she can "resurrect" his image from the water, and this is the final important imagery of the novel. She closes the story by carrying on the legacy of her brother.
The landlord as an allegory for the American treatment of immigrants
Some cultures have the virtue of treating foreigners as families as a central facet of their culture. America is not one of them. In the novel, the nation is represented by the agency of the landlord. As a girl, the narrator was trained to view white Americans as essentially authority figures, often in contest with her father, and always unfair and unkind. In fact, the man in question ends up facing charges after losing his temper and murdering a woman. That is the basic understanding that she comes away with.
The mother and father as symbols of sacrifice
Instead of treating her parents as failures, the author chooses to treat them with respect, honoring their sacrifices. This is clear when she promises to carry along the torch and hope for a better life. It's also clear in the constant reminders of the difficult pasts of her parents, and most of all, it's evident in the scene where she protects their honor by dancing for the crowd.
Agonizing meditation as a metaphor for PTSD
When the daughter chooses to spend sleepness nights being a silent companion to her father's meditation, that's a metaphor for her openness to use her empathy to understand the emotionally difficult reality of her father's situation. She talks about him as if he is at war with unknown forces in unknown places of the mind, which is a spot-on representation of mental health issues, especially the staggering weight of PTSD and paranoia.
