As the protagonist of Regeneration, Rivers undergoes a personal growth that forms the foundation for the structure of the story. This character is loosely based on the real W.H.R. Rivers, who worked as a psychiatrist at Craiglockhart from 1916–1917 and served as a treating physician for Siegfried Sassoon. Like the character, the real Rivers had a stammer that he sometimes found difficult to control, though his father was a speech therapist. Rivers studied anthropology and went on several expeditions before returning to Cambridge to do research on nerve regeneration with a friend, Henry Head. At Craiglockhart, Rivers officially treated Sassoon for an "anti-war complex." The real Rivers writes about Sassoon under the alias "Patient B" in his book Conflict and Dreams.
Though Rivers the character is based upon the real Dr. Rivers, Barker's accounts of his discussions, thoughts, and moral dilemmas are entirely fictional. In the novel, Rivers is a dynamic character who develops and changes throughout the work—ironic, since it is his job to change others. With a traditional Victorian education and a strong belief in honor, Rivers feels bound to his duty to heal men so they may return to war. Rivers is not close-minded, however; in fact, his deep sympathy for the suffering of his patients causes him to rethink previously solid beliefs. He feels a deep conflict about whether he is doing the right thing by treating men just so that they can return to war and be killed. Furthermore, Rivers feels guilty over the level of control and influence he has over his patients. After watching Dr. Yealland's method of electro-shock therapy, Rivers wonders how much he really differs from his harsh colleague. The novel charts Rivers's slow journey of realization and growing doubtfulness about the justification for the death of an entire generation.
The real Siegfried Sassoon, much like the novel's character, was abandoned by his father early in life. Though he was a decorated soldier, Sassoon declared in 1917 that he no longer agreed with the war. Sent to Craiglockhart, he was treated by the real Dr. Rivers, and there is evidence that he regarded Rivers as a father figure. In his memoir Sherston's Progress, Sassoon refers to Rivers as his "father-confessor." After his stay at the hospital, Sassoon did decide to return to the war in France. He survived and went on to publish many more literary works after the war was over.
In Regeneration, Sassoon the character is an extremely sympathetic figure. He is a man who stands by his convictions and refuses to be used by those who would sacrifice him for their ideals—namely, pacifists. Though Sassoon returns to the war, we do not get the impression that he has been influenced to sacrifice his beliefs. When asked point-blank in the Board meeting about his views toward the war, he replies quite directly that his views have not changed at all. In an environment of madness, Sassoon is sane. His importance is heightened by his individuality.
Though Sassoon holds strong beliefs, he is not foolish in matters of social practice. He believes that homosexuals should be treated with more tolerance, but he sees the practical necessity of remaining silent about his own sexuality. He is a caring and fatherly figure to his troops and to Owen, whom he steers toward a better use of his poetic gifts. Above all, Sassoon, as portrayed in Regeneration, acts as a teacher, guiding those with whom he speaks toward a better knowledge of themselves and of society.
As a soldier who has had a difficult life both at war and at home, Prior is a conflicted and complicated character. From what we know, Prior is entirely fictional, which frees Barker from any constraints linked to Prior's beliefs, past, or future. As a result, Prior is deeply nuanced in his thoughts and reactions. We receive a glimpse of Prior's past when his parents, Mr. and Mrs. Prior, come to visit Craiglockhart. Prior's conflicted nature is not surprising, considering that his parents come from such differing views with regard to their son's well being. Such emotional conflict clearly causes Prior stress; he develops a physical asthmatic reaction to their visit.
Prior's belief system is complicated: He believes he has a duty to serve, but his ambitions preempt this duty as a reason for him to return to the war. Prior wants to prove to himself that he is a good soldier, a man who will not break down under pressure—a masculine figure. Opposing this desire, however, is the very real fear that he will be killed in the war. Prior is hesitant to admit this fear, and he cries when he is told he will not be returning to the war. He is in many ways a self-absorbed character; he cares first and foremost about his own recovery and his own experiences. When he takes Sarah to the shore, he is envious of the people around him who are able to escape the war experience. In the end, Prior endeavors to lead a normal existence, taking solace in the fact that there will be a part of his life—Sarah—that is not tarnished by the war.
In Regeneration, Dr. Yealland is a static character who serves as a foil to Rivers. Arrogant in his actions and demeanor, Yealland refuses to consider that there could be any method better than his. He points to the numerous and immediate results of his electro-shock therapy, using them in an attempt to prove the effectiveness and efficiency of his method. Yealland believes that men who suffer breakdowns in the war are degenerates "whose weakness would have caused them to break down, eventually, even in civilian life." Such an attitude allows him to treat his patients as mere projects rather than human beings. When a frightened patient asks if the treatment will hurt, Dr. Yealland refuses to answer his question, and instead replies that he forgives the patient for speaking. To Yealland, "curing" can be achieved in one session. It involves "breaking" the patient, holding total control over and no sympathy for a man who is powerless against him.
In the novel, Dr. Yealland's character serves a larger allegorical purpose. He is a metaphor for the control the government exerts over its people. Unsympathetic to individual cases, the state continues in its "aims," fighting a war that seems purposeless and sacrificing helpless men. Like the state, Yealland does not consider the consequences of his actions; he never follows up with his patients in the one session after he releases them. Yealland's methods contrast significantly Rivers's, but they encourage us to consider the similarities of psychiatrists bound by their "duty" to heal.