Doc's daughter and he don't really get along well.
Because of Doc's traumatic life, he adopts a daughter in an attempt to reconcile those difficulties in his life, but then ironically, she doesn't really see things the same way he does, and in the end, she finds herself in the wrong crowd making a life for herself the hard way.
Doc's savior complex makes it so he needs a savior most.
Doc's desire to rectify a situation he wasn't responsible for in the first place is a symptom of PTSD, but regardless, he feels urged to fix life for at least one woman, but this leaves him prone to flashbacks, which we read as a literary feature, but which in real life are highly emotional, often traumatic. In the end, he depends just as much on his daughter as she relies on him. Perhaps there is an answer there.
Doc's girlfriend isn't quite a girlfriend, but still messes up his relationship with his daughter.
Ironically, Mary Burns doesn't end up being very helpful. Yes, Doc and Sunny had a difficult relationship, but Sunny was obviously hurt by the way Doc tried to include Mary, and Sunny doesn't benefit at all. In fact, no one really benefits, which isn't what the reader would have wanted from this. Although the novel ends up arguing that people can help us with the difficulties of daily life, it doesn't show that here. Instead it shows how a bunch of unguided people hurt each other badly.
The irony of Japanese life in America.
Japanese veterans weren't exactly the most popular people in America, it goes without saying. But, that doesn't stop Doc from participating in community and from thriving. This is a nice comment on his integrity and patience, as well as his willingness to see the best in people.
This is doubly ironic: First, it's ironic that a Japanese veteran ends up being a treasured citizen, because historically, America hasn't treated Japanese people kindly at all. But it's also ironic that this particular veteran, although he was technically an enemy during the war, actually spent most of his time helping the rape victims from his own army's pilaging. So even there, Doc defies American assumptions.
The irony of flashbacks as a literary device.
Flashbacks are an important part of literature, and most of the time, they are tremendously informative and interesting, leading the reader to encounter Doc's flashbacks with a sense of intrigue. But for Doc, they're PTSD attacks, flashbacks without his consent. He finds himself in the middle of one line of thought, and then suddenly, he's describing the twisted ways that his army treated Korean women. The irony is that the flashbacks are actually indications of PTSD, not just some interesting narrative tool.
