In Sir Gawain and the Green Knight, the Green Knight insists on Gawain’s moral obligation in their agreement. Why does it happen? Because a high sense of honor inherent to a noble knight requires to keep a word once given. A strike for a strike is the unbreakable term of the deal, which no genuine knight can escape.
Detailed answer:
Sir Gawain and the Green Knight is a chivalric romance narrating the famous trail of Gawain, nephew of King Arthur, and showing the majesty of the protagonist’s nature during his adventures. The poem starts with a story about how King Arthur, encircled by Knights of Round Table, welcomes the new year. Amid the feast, an unfamiliar knight rides into the hall, astride a horse. His appearance, including his body and clothes, was all bright green. Thus, his image was of a mystical or even demonic nature.
The mysterious knight boldly announces that he seeks a brave man who can accept an unusual challenge. According to the terms of the challenge, someone present can hit him with an ax. However, one year and one day later, the Green Knight will retaliate. Initially, nobody dares to accept such specific conditions. When Arthur himself, offended by the knight’s impudence, lifts an ax in his hands, Gawain ceases him and takes everything upon himself. Among all present, only Sir Gawain was courageous enough to accept the challenge. By doing this, he punishes the insolent guest for his provocative prank.
Gawain raises the ax and chops off the impertinent knight’s head. Nonetheless, the knight remains alive. He serenely raises his head, mounts his horse, and leave, reminding Gawain of the appointed time and place. The Green Knight firmly believes that a true knight will never break his word, even if it will cost him his life. Gawain successfully proves this idea throughout the plot development.