The common themes that Romantic period, the victorian age, and the modern era is a theme about revolution and democracy. In the romantic period, characters have a romance like story but the revolt still circles in the storyline, it is same with the victorian age and modern era where the fight for democracy is being the center of the story.
Subject: A little dog is taken into a abusive home
Theme: Those who are abused learn to abuse the weak.
It can be said that chivalry affected the characters when the Knights exhibited their behavior. The Green Knight challenged the knights´honor and so Sir Gawain asked the King to accept that challenge. It seems that he wanted to show his loyalty (value of Chivalry) to King Arthur. Later on, the Green Knight promised to keep his word (value of Chivalry).
