Wu Yin

He knew Bai Zhongtian from childhood and had always had better talent/skills than him including reaching Martial Saint Realm and entering First City first. When they met up with each other again was challenged by Bai Zhongtian in refining pills and beat him, after seeing this Gu Ruoyun challenged him and beat him so he had to become the servant of Bai Zhongtian for the rest of his life.