War
There are brutal, evocative descriptions and imagery of the death and destruction caused by the Vietnam War throughout A Man of Two Faces. As Nguyen and his family grow closer to their immigration to America, the violent imagery caused by the war becomes more prevalent, hastening their departure.
Loneliness
There is quite a bit of use of emotional imagery throughout the novel, especially imagery related to loneliness. Ngyuen's loneliness is described in increasingly intense and vivid detail as he navigates the foster system after being taken from his parents. As his sense of loneliness increases, the level of description in those emotions does, too; they are almost another character.
Family
The imagery surrounding family is littered throughout the novel. When Nguyen feels distant from his family, familial imagery crops up much less frequently. However, as he grows closer to them, it crops up more frequently.
America
America is not only a powerful symbol; frequent American imagery throughout the book underscores the aspirational quality that America has to many immigrants.