Gu Youyou's biggest trait is being tsundere. If she really felt that killing the wrong person didn't matter, she wouldn't have stopped when Zhang Chi yelled for her to.
"How about we use a secret signal? I think you're the real deal."
Zhang Chi was the first to express his stance, but Gu Youyou didn't appreciate the gesture.
Zhang Chi thought he was genuine, but she still thought Zhang Chi was fake!
"Whether you believe in me or not isn't important. What's important is whether I believe in you."
Gu Youyou, full of queenly demeanor, looked at Zhang Chi and then suddenly remembered something.
"That's right, didn't you promise me that if I could save Wenren Li, you would become my Demon Slave? If you obediently accept my Demon Seal, I'll believe you're real."
Gu Youyou was up to this trick again; she had scared Zhang Chi the same way last time, but when Zhang Chi was truly ready to accept it, she backed out.