Who He Is
Polonius is the king’s counselor, father of Laertes and of Ophelia. He loses himself in his own instructions, and the play always shows him in a hiding place: he sends someone to spy on his son in Paris, hides to hear his daughter with the prince, and ends up behind the tapestry of the queen’s chamber, where he dies, struck by Hamlet, who takes him for Claudius.
Trajectory
In scene 3 of Act I, he bids farewell to Laertes with a list of precepts of conduct, and then questions his daughter about the prince: he calls the prince’s vows counterfeit coin and forbids any further conversation. Ophelia obeys.
This above all: to thine own self be true; / And it must follow, as the night the day, / Thou canst not then be false to any man.(I.3)
In scene 1 of Act II, he gives money to Reynaldo and sends him to Paris to investigate Laertes through small slanders, and loses himself in his own instructions. Ophelia comes in frightened, describing the prince’s appearance, and Polonius concludes that it is madness of love, regrets having suspected him, and runs to tell the king.
See you now; / Your bait of falsehood takes this carp of truth;(II.1)
In scene 2 of Act II, he announces the messengers from Norway, brings Claudius and Gertrude a love letter from the prince and proposes spying on him with Ophelia. Hamlet mocks him. In scene 1 of Act III, he hides with the king to hear Hamlet and Ophelia and suggests that the queen confront him after the play. In scene 2 of Act III, he confirms her summons. In scene 3 of Act III, he warns that he will hide in the queen’s chamber.
In scene 4 of Act III, it is the hiding place that kills him: on hearing him stir behind the arras, Hamlet thrusts through the curtain with his sword, convinced that he is killing the king. In scene 3 of Act IV, Hamlet says that he is at supper, eaten by worms. In scene 5 of Act IV, Claudius admits that he was buried in secret and that Laertes returned from France.