One example of poetic justice is the fate of the character Mr. Bumble in the Charles Dickens novel "Oliver Twist." A wealthy sadist at the start of the novel, Mr. Bumble ends the tale as a pauper, working in a house he once owned and frequently enduring humiliation from his wife. Poetic justice occurs when good characters are rewarded and bad characters punished through an ironic twist of fate.
Mr. Bumble's fate accurately illustrates the ironic turn in a character's arc that characterizes poetic justice. He begins the novel as a cruel authority figure who enjoys tormenting Oliver and the other orphans under his charge. Mr. Bumble marries Mrs. Corney out of a selfish desire for money but winds up penniless, humiliated and tortured by his wife, just as Oliver and the other orphans are tortured at the start of the novel by Bumble. Mr. Bumble's moral failings are ultimately responsible for his own downfall, and his fate reflects the negative choices he has made.
Another example of poetic justice occurs in Sophocles' classic Greek tragedy "Oedipus the King." Oedipus is fated by the Delphic Oracle to kill his father and marry his mother. Desperate to escape this outcome, he flees his home and travels to another kingdom, where he unknowingly fulfills the prophecy. Oedipus' attempt to avoid his fate results in him fulfilling it.