Yun Qianyu naturally noticed the look in Xiao Jiuyuan's eyes, but she didn't pay him any attention. Instead, she furrowed her eyebrows and thought about the Ancient Prescription of Ten-thousand Poisons in her mind. The poisons described in this book were very complete.
Yun Qianyu believed that the thing affecting Xiao Jiuyuan's body would definitely be recorded in that ancient text.
'What kind of poison can devour a person's spiritual energy, but wouldn't be noticed under normal circumstances?'
After a quick search, Yun Qianyu found something that seemed to match the description, a very sinister poison which required feeding a fetus with nine poisons, and then refining the poison from the baby's blood. Since the baby's blood itself was the poison, it was very hard to detect it as it could blend into the victim's blood. Unless the poison was active, it would never be detected.
'Is this the poison affecting Xiao Jiuyuan?'