Yu Sui wouldn't tell Su Feng that she knew Qingkui existed.
Given how clever Su Feng was, he would realize that Lady Su's lukewarm treatment of him all these years might have something to do with another child.
If she knew Qingkui existed and had still lived like this for eighteen years, then in Su Feng's eyes, she would seem rather pitiful.
Even if Su Feng's pity came from a place of kindness, Yu Sui didn't want it.
The thought of being dragged into the mother-daughter relationship between Lady Su and Qingkui made Yu Sui feel sick.
It was like the time she had looked up in Three Thousand Paths and discovered that her father's face belonged to Nangong Ming. She hadn't felt hatred. She'd felt sick.
When Yu Sui had just been born at Mount Luo Peak and Qingkui had faked her death, Yu Sui had still been an infant. There was no way she could have known about Qingkui, much less remembered her.
But Qingkui remembered Yu Sui.
Yu Sui didn't know how Nangong Ming had raised this daughter, but with Qingkui's talent, he must have favored her greatly.
Nian Qiuyan had said that Nangong Ming wouldn't interfere in the Qingyang Hundred Bandits' decisions. That meant he acknowledged Qingkui's ability.
Qingkui thought Mei Chengyu was in the way and wanted Yu Sui to deal with this troublesome obstacle.
In Qingkui's eyes, when a man became bewitched and started showing a woman kindness, that was when he fell into a death trap.
Nangong Sui had entered Taiyi and become a Sage's disciple, rising from a Normal Practitioner to a Nine Schools Practitioner.
With that information, Qingkui wouldn't underestimate Yu Sui. Asking her to kill Mei Chengyu was a test.
What could someone who had been useless and weak for