People wear masks in front of others, which is human nature; it's just whether they wish to hide something.
Take Zhu Pingniang, for example, who always seems frivolous, gluttonous, lustful, and impatient, embodying three of the five poisons a girl should avoid. However, those who know about Zhu Tongjun's existence would just smile knowingly when seeing such a Zhu Pingniang.
The seductive demeanor wearing a black dress before the Flower Moon Building, as if a gentle tug could make it fall, is just a mask. Li Zhibai understands this, which is why she's willing to accompany her younger sister in mischief.
Li Zhibai is always such a serious person.
Yet even Li Zhibai sometimes hides her true self—like in front of Xu Chang'an.
She almost never appears before Xu Chang'an with her real face.
In front of students, she is always the serious, reliable, majestic teacher, this is a necessary aspect, not her disguise.
So, she is always dignified in front of Xu Chang'an.
