Who is Matrim Cauthon from The Eye of the World and what is their importance?

Mat is one of the three boys forced to flee when he learns the Dark One is after him. He is friends with Perrin but closest to Rand. When it seems they have lost their pursuers after leaving Two Rivers, Mat is the first to relax his guard and encourages his friends to do the same. He reluctantly admits to having the shared dreams about Ba'alzamon. In the heat of battle, Mat unconsciously uses the war cry of the Manetheren king in an ancient language but is disturbed by it later. In Shadar Logoth, Mat convinces Rand and Perrin to explore the city with him. When they meet Mordeth, Mat agrees to follow the stranger as soon as treasure is mentioned. He picks up a dagger to use against Mordeth when the spirit turns against them and then is reluctant to leave the treasure when they flee. He keeps the dagger, not admitting to having it when Moiraine asks.