Since he had successfully taken over Rong Jialuo's identity, how did Gu Xijiu unravel his secret? Gu Xijiu pinched her now pale red lips and answered calmly, "Rong Jialuo was once my friend." Gu Xijiu knew her friends well enough, and that included Rong Jialuo.
One's temperament might differ due to the change in his or her social status. One's personality, however, would not change to an undistinguishable extent.
Although he always put on his grim expression, Rong Jialou was naturally a little shy and introverted. For the past few months, 'Rong Jialuo' behaved somewhat similarly, with a lack of amiability; but Gu Xijiu could still notice his mild sense of evilness through his eyes. That was when she started to suspect his true identity.
Before this, she even tried to perform several tests on him secretly, but the results remained normal, which led her to assume that she overthought the whole situation.