Berenger's transformation is the true metamorphosis in Rhinoceros. While the other characters physically turn into rhinoceroses, embodying the savage natures they had formerly repressed, Berenger's change is moral and completely opposite from his position at the start of the play. He begins as an aimless, alienated Everyman who drinks too much and who finds little worth in life, except for the beauty of Daisy, his co-worker. He is bored by his work, too lazy to culture himself, and wonders if life is a dream—that is, if its absurdity is the product of a dream-like state of absurd logic, and if life, like a dream, is controlled by unconscious desires. Despite his escapism through alcohol, he holds on tightly to his human identity, never comprehending why someone would want to be anyone else. While his passivity is the underlying cause of the metamorphoses, helping promote the climate of irresponsibility and indifference, it is his recognition of life as an absurdity that prompts him to change his character, rather than accept the presence of the rhinos. Yet he remains indecisive nearly to the very end, losing his faith in humanity and finding the rhinoceroses beautiful. In the last line of the play, however, he overturns his weak will and lack of responsibility by deciding to save humanity against the tyranny of the rhinos.

Berenger's decision, however, is not totally unforeseen. His love of Daisy, as mentioned above, reveals he has emotional desires for another human. At one point, when it seems to him that he and Daisy will be united at the expense of their co-worker Dudard's departure and metamorphosis, Berenger exclaims "Happiness is such an egotistical thing!" Yet his desires turn out not to be so self-centered. Even when Daisy abandons him to become a rhino, and when other friends insult him and do the same, he feels guilty for pushing them out, although they would have metamorphosed without him. He does not love Daisy alone; he loves humanity, and is willing to take responsibility for its fate. This "will" of responsibility, rather than the will of power the other characters treasure, is what ultimately galvanizes Berenger's final line of resistance, "I'm not capitulating!"