In his previous life, after he inherited the throne, he had secretly planted someone beside Duan Huai to prevent him from exposing himself. After all, Duan Huai was personally promoted by Emperor Hao, and Duan Huai was also considered Emperor Hao's trusted aide. Who cared if Emperor Hao had told Duan Huai that he was not of the royal bloodline?
Duan Huai not only did not know that he was not of royal blood, but he also had such a huge weakness that he could leverage on.
Therefore, he summoned Duan Huai to the capital and pretended that someone had secretly told him everything. Not only did he promise Duan Huai that no one would know about this, but he also made Duan Huai prove his loyalty to him. Duan Huai was naturally grateful and extremely loyal that he would not expose his matters to the world.