What is the relationship between Sunny and Ganlong in Zhu Huan Gege?

Sunny in Princess Zhu Huan is the niece of Emperor Qianlong.

Sunny, Qinggege, the daughter of the late King Yue, won the favor of the Queen Mother and often accompanied her. Gentle and poetic, he formed an indissoluble bond with Wei Zi, a swallow from the folk, and rescued him from danger several times with his own wisdom. He also found his true self from them, and refused the Queen Mother to marry Erkang. Wei Zi once said that it was an iceberg with a cold appearance and a warm heart. Later, I met Xiaoyan's brother Xiao Jian and had sex with her. I am willing to abandon my identity and go far away. After several disasters, I finally got married, and Xiao Jian became a civilian couple, living in seclusion in Dali.