Final answer:
Sir Gawain's prophecy comes to fruition when he confronts the Green Knight and fulfills the exchange of blows at the Green Chapel.
Step-by-step explanation:
Sir Gawain's prophecy in the English literary work 'Sir Gawain and the Green Knight' comes to fruition when he confronts the Green Knight at the Green Chapel. The Green Knight challenges Gawain to exchange blows with him, promising to meet Gawain a year hence to return the favor.
Gawain fulfills the prophecy by traveling to the Green Chapel and allowing the Green Knight to strike him, thus completing the exchange.
This prophecy is fulfilled as it was foretold, demonstrating the overall themes of honor, loyalty, and the importance of keeping one's word in chivalric literature.