Yi Chen had seen countless false faces in his lifetime, even his seemingly 'intimate' playmates were always wearing a false mask.
If one couldn't discern, they were doomed to become the lowest of beings.
That's why,
when Yi Chen conversed with the old man in the sewers, he could perceive the false mask the other was wearing just from two sentences; it was too obvious, with no acting involved at all.
However,
the theater owner before him, though wearing a mask on the outside, was of a very pure essence.
There was nothing false in his words or deeds, similar to the innkeeper from Green Lake Town.
This was also the fundamental reason why Yi Chen decided to perform seriously,
as establishing a relationship with the 'Moonfolk' would be very beneficial for the progress of the mission.
Moreover, Yi Chen had also gleaned an important piece of information from the script they had just performed.