Qing Cai refused to drink it. No matter how Qing Shi advised him, he refused to drink it and insisted that there would be other ways to treat his poison. He even said that Sima You Yue had done this to him on purpose, and that it would not have any effect even after drinking it.
"If it has no effect even after you drink it, I will naturally look for her again!" Qing Cheng shouted, "If you don't drink it now, nobody will pay you any more attention!"
Qing Cai quieted down in the face of his grandfather's rage. The one person that he was afraid of was his grandfather. The moment he got angry, his entire body would tremble.
Also, he was afraid. He was afraid that they would really not bother about him anymore. As such, even though he was extremely unwilling, he could only agree.