Final answer:
The Pardoner in The Canterbury Tales unexpectedly admits to his own corruption and deceit in his prologue. He uses his sermons not to save souls but to swindle money from those seeking pardons, symbolizing a critique of Church corruption.
Step-by-step explanation:
In Geoffrey Chaucer's The Canterbury Tales, the unexpected revelation in the Pardoner's Prologue is that the Pardoner is quite open about his own corruption and deceitful practices. The Pardoner admits to preaching against avarice, but not to save souls; instead, he does it to make money from the selling of pardons and relics. He is aware that he is guilty of the very sin he preaches against and takes pride in his ability to deceive and manipulate his audience for financial gain. This self-revelation is shocking, especially given the religious context in which he operates, and serves as a critique of the corruption within the Church at the time.