Shangguan Mingyue was tense precisely because she feared that Xiao Chen's intentions were not pure and that he might harm Xiao Yingxue.
Given what she knew, Xiao Yingxue had a mysterious past, was solitary and reserved without any family or connections. How could she suddenly have a brother appear out of nowhere?
On the other hand, Xiao Chen claimed to come from Fengyue Country and knew how to directly steal others' memories through techniques of the Demonic Path, giving off an aura of peculiarity throughout.
Before figuring out Xiao Chen's character and intentions, she could not feel at ease, thinking Xiao Chen was seeking out Xiao Yingxue to harm her.
However, what she didn't expect was that Xiao Yingxue, who had been indifferent even to her, her lifesaver, would now follow Xiao Chen obediently like an attendant.