Xiao Zai remembered Ru Long mentioning 'a long lost relative' bringing him to Zui the first he and Chu Yun met him. It made sense with the information Gu Wei was now telling him.
Ru Long probably knew about his twin sister.
Maybe he even knew everything about what happened to Xiao Yao. About the tragic events that led him back to Su and his sire.
Gu Wei looked pleadingly up at Xiao Zai, holding on to the sleeve of his golden robe. "I didn't know he was Xiao Yao's son. I would never endanger you. I had no idea what became of Xiao Yao's children, he never told me, I assume for their own safety. I hoped they were living good lives somewhere, unaware of their tragic beginnings."
Xiao Zai pulled his sleeve away from Gu Wei's hold. "But you would endanger Chu Yun."
He got up to his feet and stepped away from his dam, who looked at the distance between them as if it were a moat filled with snakes.