Gu Zun is the brother-in-law of Black Dragon King. He once plotted against the Dark Crow and was almost killed by him. But Black Dragon King intervened due to a vow to his late wife to protect him and promised to punish him instead. Gu Zun was instead cast into an abyss and his cultivation crippled for a time.
He later seizes majority of the power in the Heaven Suppression City Sect after the passing of the latest sect master and causing Black Dragon King's death. Li Qiye complimented his unshaken Dao Heart but remarked that he would be unable to become an Immortal Emperor. So Gu Zun decided he was more suited to the Dark Crow's position as the Dark Hand Behind The Curtains, but he lacked the immortality and resources of the Dark Crow which is why he was obssessed with the Treasure House in Heavenguard; which turned out to be empty and opened with his blood as a test for him. After being unable to defeat Li Qiye, he sacrifices himself to help exterminate an Ancient Ming lair in the battle against the Soaring Immortal Sect.