A cultivator from the Blood Stream sect.
He went to the Fallen Sword Abyss as one of the desciples from his sect to reach Earthstring Foundation Establishment. Unfortunately for him, he couldn't make it. When Bai Xiaochun was going through his own tidewaves, Zhao Wuchang was one of the cultivators who tried to prevent him from doing so and kill him. He fled as soon as Bai Xiaochun finished his breakthrough and started killing his assailants.
Later, when Bai Xiaochun infiltrates the Blood Stream Sect disguised as Nightcrypt, Zhao Wuchang is the one who came looking for him and brought Bai Xiaochun to the meeting with other "failures" who couldn't reach Foundation Establishment.
During the subsequent trial by fire, he is the only one to get a Foundation Establishment pill from Bai Xiaochun. To achieve that, he pays a heavy price and offers Bai Xhaochun 60 years of being his slave. He even extracts a drop of Spirit Blood from himself that contains a sliver of his soul, and gives it to Bai Xiaochun. As a reward, he gets a single Foundation Establishment Pill that lets him reach a Mortal-Dao Foundation Establishment with a strong foundation.
The reason why he goes to such lengths - is because his clan is on the decline and he fears that rival clans, who recently got their Foundation Establishment experts, would exterminate both his clan and himself if he doesn't reach Foundation Establishment.