Zhang Fei
Guan Yu meets Zhang Fei at Gucheng (古城) after crossing five passes and slaying six generals. Zhang Fei is initially suspicious of Guan Yu because he mistakenly believes that Guan Yu has betrayed their oath of brotherhood and joined Cao Cao. Despite explanation from Liu Bei's spouses, Zhang Fei refuses to listen and attacks Guan Yu. Both of them are locked in a duel when Cai Yang (蔡陽), an officer under Cao Cao, leads his soldiers to attack them. Zhang Fei demands Guan Yu to prove his loyalty by killing Cai Yang within three rounds of battle drum rolls, so Guan Yu turns around and kills Cai Yang before Zhang Fei finishes beating the drum. He regains Zhang Fei's trust in him and embraces his sworn brother.