Polonius is a proud and concerned father. In his first line he tells us he hesitates to let his son Laertes go abroad, and he draws out his last meeting with Laertes because he’s reluctant to see him go. In the same scene, Polonius advises his daughter Ophelia to avoid Hamlet because he’s worried about her. The secure and happy family unit of Polonius, Laertes, and Ophelia provides a stark contrast with the dysfunctional unit formed by Claudius, Gertrude, and Hamlet. The happiness of Polonius’s family is reflected in his children’s reaction to his murder. Laertes passionately pursues revenge, and Ophelia feels so struck with grief that she goes mad. At the same time, Polonius reveals himself to be a far from perfect father. He sends Reynaldo to spy on his son, and he uses his daughter as bait to trick Hamlet. Polonius’s actions suggest that in Hamlet, even relationships that seem loving are ambiguous, a fact which contributes to the play’s atmosphere of doubt and uncertainty.
Polonius also provides Hamlet with its main source of comic relief. As a comic character, he consistently shows himself less wise than he thinks. For instance, in Act Two he cleverly announces that “brevity is the soul of wit” (II.ii.), but he does so in the middle of a tediously long speech. The fact that Polonius gets himself so wrong contributes to one of Hamlet’s central themes: the challenge of self-certainty. Polonius’s amusing lack of self-awareness serves as a comic foil to Hamlet’s existential struggle with self-knowledge. In this sense Polonius offers an alternative and far less extreme perspective on the impossibility of perfectly knowing oneself. This difference between Polonius and Hamlet results in a powerful example of irony in Act Three, when Hamlet mistakenly kills Polonius, thinking it’s Claudius. Whereas Polonius’s lack of self-awareness is ultimately harmless, Hamlet’s lack of self-certainty drives him to his first act of violence, which completely and tragically misfires.