Zewu-Jun will be extremely upset if he finds out. It is important to spare him that. Meng Yao knows the exact way that it will burn.
Meng Yao's hands are shaking. He is... possibly also upset. Whore. And asking for it. He wants to storm back inside the cell and slice Wen Chao's tongue into ribbons, but then he will not be able to stop until the prisoner is dead. They can't afford that.
Whore. And blood, and his head hits the stairs, and -
Anyway. Lan Xichen shouldn't find out. If he has survived, and if he recovers from his injuries and returns to them - he will need his sister to be okay.
(He will need his sister to be alive. Not all of them live.)
People are different, and Lan Zhan is a difficult person to get to know. Meng Yao doesn't know what Lan Zhan needs. He always brought his mother wine. (She would have only one small glass. As she told Meng Yao, it was not proper to take more in one sitting.)
It's a starting point, at least, and alcohol is certainly easy to find.