Central to "The Red Convertible" is the relationship between Lyman and Henry. Lyman narrates the story to honor and preserve his brother's memory.

As the story unfolds through Lyman's viewpoint, the reader doesn't gain direct insight into Henry's personal thoughts and feelings. Yet, Henry's words and actions reveal his profound love and appreciation for their bond. Before leaving for the Vietnam War, Henry wanted to give the car, which had brought them immense happiness, to his younger brother. He likely doubted his return and hoped for Lyman to become more independent. This might also explain why his letters home were infrequent. After returning from the war, Henry was a different person. When Lyman purposely damaged the car to encourage Henry to fix it, Henry understood Lyman's intention. Instead of getting upset, he repaired the car for Lyman. Henry's apparent suicide while alone with Lyman suggests that Lyman was the only person Henry truly trusted, choosing him to share his final moment with.

Henry was once a lively, funny, and carefree young man. However, after spending three years in combat during the Vietnam War, he returned as a completely different person. Lyman describes this change in Henry after the war:

When he came home ... Henry was very different, and I'll say this: the change was no good. You could hardly expect him to change for the better, I know. But he was quiet, so quiet, and never comfortable sitting still anywhere but always up and moving around ... He'd always had a joke ... and now you couldn't get him to laugh, or when he did it was more the sound of a man choking, a sound that stopped up the throats of other people around him. They got to leaving him alone most of the time, and I didn't blame them. It was a fact: Henry was jumpy and mean.

Like many veterans, Henry became emotionally distant, hesitant to talk about his experiences, and unsure how to adjust to civilian life. At the time, post-traumatic stress disorder wasn't well understood. Lyman notes that his brother spent three years in combat, saying, "By then I guess the whole war was solved in the government's mind, but for him it would keep on going." Instead of seeking ways to rebuild his life, Henry chose to remain stagnant, spending his days watching television and isolating himself. Despite his family's deep affection for him, they lacked the resources to address Henry's problems. Although he appeared to improve after fixing the car, this change was short-lived—or perhaps even feigned. The internal struggles he faced ultimately led to his downfall.

Louise Erdrich’s story can be viewed through the lenses of both modern history and American Indian cultural mores. From the mid-1960’s to the mid-1970’s, the United States drafted thousands of men to fight in the Vietnam War. Because the warrior tradition is a key concept in Native American culture, the number of American Indian men serving in the military is among the highest of any ethnic group. As warriors, Native American men uphold the honor of their tribe and prove themselves as men. A warrior puts his life on the line as the ultimate sacrifice to ensure his people’s survival. Facing death in battle is a spiritual rite of passage and an important step in gaining respect and status in the Native American community.

When Henry volunteers for active duty, he is maintaining these distinctive cultural values. However, serving in the white man’s war leaves Henry psychologically fragile and emotionally lost. One of the more grotesque images Erdrich uses to illustrate the extreme damage to Henry’s psyche is the blood dripping down his chin after he has bitten through his lip while watching television. He does not notice that he is bleeding when he sits down at the dinner table and begins to eat. Lyman notes that Henry is swallowing his own blood as it mixes with the bread in his mouth. Vietnam veterans from many different backgrounds suffered from post-traumatic stress disorder after they returned home from the war, but Henry’s case is made worse by the fact that his cultural expectations as a Native American warrior have not been fulfilled. For him, there is no glory or honor, only anger, despair, and hopelessness.

“The Red Convertible” is also a bitter coming-of-age story. At the beginning of the narrative, the brothers enjoy a carefree camaraderie as they take off in their new car and travel from state to state, visiting other reservations. Their visit to Alaska takes on an otherworldly quality in that their stay with Susy’s family harkens back to the distant past when Native American traditions remained intact and unsullied by European influence. During the summer they spend in Chicken, they live in mythic time in a place in which the sun never sets and each day flows seamlessly into the next. Just before they leave for home, Henry dances with Susy perched on his shoulders, her long hair swinging around him. He comments that he always wondered what it would be like to have long hair. Ironically, his “borrowing” of a woman’s tresses is the closest he comes to resembling his warrior ancestors. As a contemporary United States Marine, his hair is shorn, and he is sent to fight in a controversial war against a nation that is no direct threat to his own country. His disillusionment coupled with the humiliation of his imprisonment as a prisoner of war cause him to lose his innocent idealism as well as his cultural bearings. Henry’s mental state has a direct impact on his family, especially his brother. Henry’s postwar illness and subsequent suicide initiate Lyman into the adult world.