Kzanol is important less as an individual than as the last representative of the thrints. Through his memory, the reader receives an intimate view of the Slaver Empire as it existed millions of years ago. He believes that his telepathy renders him superior to all other beings, but this is not seen as personal evil but simply as part of the psychology of the Slavers. As with many of his aliens, Niven shows that their ethics are frequently shaped by their environment and heredity. Rather than pass judgment on purely human terms, men must pragmatically accept their alienism.

Larry Greenberg, the novel's hero, is able through his limited telepathy to accept alien points of view. He enters Kzanol's mind and is nearly taken over by the thrint but also gains his memory. He defeats Kzanol by his new knowledge of thrint culture and by a practical joke he...