As a knight, Sir Gawain could not allow his king to fight. He is known for his chivalry and loyalty to King Arthur, his uncle. Although the youngest among the knights of the round table, he is a reputable knight, known for his courtesy and skill with a sword but somehow, he lacks self-confidence. Despite this, he still could not allow King Arthur to participate is such a "silly game," as he mentioned and requested the King grant him the honor of dealing with the Green Knight in his stead.
