During the war with the twelve northern kings, Gawain arrives at Arthur's court with his mother and two brothers.
In his first adventure as part of Arthur's court, Gawain refuses to grant mercy to a knight who asks it, then kills that guy's lady by mistake.
In his second adventure, the lady Gawain is protecting leaves him in disgust when he refuses to rescue a knight in trouble. Then, Gawain promises to help the knight win his lady, and sleeps with her instead.
Later, Gawain participates in the ambush of Sir Lamerok in which Aggravayne stabs him in the back.
Although Gawain tries to dissuade Aggravayne and Mordred from exposing Launcelot and Gwenyvere's affair, when Launcelot kills Gareth and Gaheris, Gawain swears he'll take vengeance on him.
He then persuades Arthur to go to war with Launcelot, and refuses Launcelot's offer of a peace agreement.
Gawain eventually fights a total of three one-on-one battles with Launcelot, but is overcome by Launcelot every time.
When the wound he received in his most recent battle with Launcelot reopens during a naval battle against Mordred, Gawain begins to die.
On his deathbed, Gawain writes a letter reconciling with Launcelot and asking him to come to Arthur's aid.