Lost You Forever / Eternally Yearning For You / Chang Xiang Si / 长相思 Wiki

The Grand Emperor, Shao Hao, is Xiao Yao's royal father and A'Heng's divorced husband. He is the emperor of Gao Xing. His younger daughter is Ah Nian.

In Once Promised

He was engaged to A'Heng at the beginning of Once Promised and later married her, even though in name only.

In Lost You Forever

After his public divorce with A'Heng, he did not marry another even to the opposition of his officials and only had a concubine, who looked like A'Heng. Ah Nian is his daughter with this concubine.