As defined by Aristotle in his Poetics, the reversal of fortune in tragedy is the inevitable but unforeseen result of some action taken by the hero. This reversal is essential to tragedy; if the hero's downfall occurs from outside forces, Aristotle terms the play a misadventure, not a tragedy. Therefore, since Shakespeare's Hamlet is a tragedy, the character Hamlet does, indeed, experience a reversal of fortune. On the other hand, Laertes, not being the tragic hero, experiences only a recognition.
Fraught with indecision and melancholy, Hamlet spends much of the play in self-deliberation and spiritual malaise. At last, in the graveyard scene, Hamlet disentangles himself from his passions and broodings, acquiring his sense of purpose and identity. Asserting himself, Hamlet declares, "This is I, Hamlet the Dane" (5.1.227). He then moves forward with his plan to rid Denmark of its corrupted court. However, he is faced with a reversal of fortune as he agrees to duel with Laertes, who has conspired with Claudius and tipped his rapier with poison so that only a wound will kill Hamlet.
Reckless and rash, Laertes charges through the play, counseling his sister against Hamlet before his hasty return to France. Boldly returning to Denmark, he discovers the burial of his poor sister and is ready to duel with Hamlet; then, having learned of his father's death from the conspiratorial Claudius, Laertes rushes into a vengeful plan against Hamlet. However, during their duel, Laertes's conscience stirs within him and he realizes that he has wronged Hamlet. As he dies, Laertes admits the evil of Claudius and begs forgiveness of Hamlet in his self-recognition,
He [Claudius] is justly served.
It is a poison temper'd by himself.
Exchange forgiveness with me, noble Hamlet.
Mine and my father's death come not upon thee,
Nor thine on me! (5.2.335-339)