O'Brien is the most complex character in the novel, particularly so because we see him at three different stages of development. O'Brien the writer/narrator, "O'Brien" the soldier, and Timmy O'Brien the young boy all possess different thoughts and emotional understandings, each of which are in tension with the others. Part of O'Brien's goal as writer/narrator is to emphasize these tensions. For example, each of these characters grapples differently with the concept of death. Timmy learned at a young age to accept death; soldier "O'Brien" attempts to retrieve that lesson to deal with death in war; O'Brien the writer connects these two approaches, emphasizing the importance of memory to his ultimate understanding of death. This type of connection and understanding of death and loss comes out of the conflict O'Brien feels as he attempts to reconcile these different phases of his life. The conflict between the three different "O'Briens" manifests itself as pain and guilt, two qualities that paradoxically motivate O'Brien to seek wellness, and simultaneously creates for him a rich reservoir for his storytelling.
It is important to remember that O'Brien authors a personal war autobiography. He constantly reflects on and interrogates choices he has made, and invites his reader to do the same. For example, O'Brien derides himself as a coward and then directly addresses his readers, soliciting from them what they would do in his situation. The audience, then, becomes part of the novel; in other words, O'Brien pulls his readers into an intimate and highly personal dialogue with him. A close reader, however, will scrutinize O'Brien's believability and call into question his reliability as a narrator. O'Brien may not be the coward he claims, because he makes readers believe that they have a fuller and less-biased perspective of O'Brien than he does. The reader, for example, can weigh O'Brien's purported cowardice against his obligation to duty. O'Brien gives his readers a unique insight into "O'Brien" by more information about the interior feelings of "O'Brien" than are usually represented in a fictional work. The reader learns the history of the character, and therefore develops a sort of hindsight in interpreting "O'Brien's" actions.
The quality that best describes O'Brien is his capacity for introspection and reflective thought, leading directly to his use of memory in the novel. Of paramount importance to O'Brien the writer is his need to remember people and events from the past, to incorporate lessons learned (or not learned) into his present life. One way to understand how O'Brien becomes a writer is that writing is a way to manifest the past — writing is memory.
"O'Brien's" preoccupation with memory and re-memory derives in part from his inability to readjust to civilian life and forget his Vietnam experience. Though O'Brien attempts to make a case that his transition out of war was easy, he exhibits symptoms of post-traumatic stress disorder, including war-related depression, isolation, survival guilt, anxiety reactions, and nightmares. Writing is, in part, an attempt to quiet these things. Rather than forgetting his past, O'Brien confronts and re-confronts the various traumas of his life to resolve some of the elements of chaos he still feels thirty years later. He seeks not an end, but a resolution, and not through denial, but through memory.
A deeply affected and sensitive individual, the "O'Brien" character spends the novel searching for an emotional home, a feeling that he had as young boy in love and which he will never encounter again. O'Brien mourns the loss of innocence he felt growing up as a boy in the Midwest and feels a sense of betrayal from the community whose cherished, misguided, and uninformed beliefs sent him to war.