Because he had previously encountered an Evil Blood Daoist, and Tang Xin'er's current condition was somewhat similar and also fit the pattern.
Qin Shaofeng suspected that the Tang Family's eldest miss might have been possessed.
However, the Tang Family's eldest miss had no weak mental strength. Perhaps the one who had possessed her was already failing and lacked the spare strength to overcome her.
That was how things had ended up like this.
After all, if the original owner had fallen asleep, then the two souls were likely fighting for control of the body within the Soul Sea of Consciousness.
Qin Shaofeng guessed that the possessor had the upper hand.
The reason was simple: after waking up, the Tang Family's eldest miss had not mentioned being possessed.
He had also learned earlier that after Tang Xin'er awoke, she was merely muddleheaded at most and displayed no strange behavior.
Of course, these were only Qin Shaofeng's guesses. As for what was truly happening, he would need to investigate further.
After explaining some of the situation, Qin Shaofeng secured an opportunity from Old Master Tang Lietian and the others to conduct a "deeper" treatment.
Naturally, Qin Shaofeng did not reveal his suspicion of possession. He merely used the excuse that Tang Xin'er might have suffered some kind of unusual trauma to her brain, or that her mental strength was too powerful and had not been properly controlled, resulting in damage somewhere in her mind.
The result was quite ideal. Old Master Tang Lietian and the others all believed him.
As for how he would gain a "deeper" understanding, Qin Shaofeng's method was quite unusual: collect several special spiritual herbs, brew them into medicinal soup, and pour it into a large bathing tub.
Then have the Tang Family's eldest miss enter the tub.