Sun Xin is a tall and strong man with eyes that shine like flames. He is Sun Li's younger brother. Sun Li is nicknamed "Sick Yuchi" because he resembles Yuchi Gong in appearance but has a paler complexion; Sun Xin is nicknamed "Little Yuchi". Sun Xin is one of the scout leaders of Liangshan. Later, he survives the campaigns and is awarded the official post "Martial Gentleman of Grace" by the emperor in recognition of his contributions. He returns to Dengzhou with his wife and elder brother.