Because the plot needs it. Zhang Congzheng is a complicated character in Dragon. He is not only the leader of attacking evil sects, but also the identity of Hejian Sect. This is mainly because when Zhang Congzheng was young, he learned some kung fu from Dragon Palace Aquarium in Donghai, China. Later, he left the Dragon Palace to join a cult and became a master of fighting evil forces. Then, after attacking the evil faction, he defected to Hejian faction and became one of the important figures of Hejian faction.