Lan Wangji thought it through using logic and reason and then rephrase the question. Now, the answer is what he correctly predicts is a productive answer. To be fair, he is just as guilty for helping him. It takes two to complete a troublemaker.

He simply listens. Not once he interrupts him. So this is what the Mad March came for, requesting as his audience. To discuss the misconduct of Wei Wuxian.

"Understood." And purposely evading his question. "I'll try my best."

By that, trying his best, meaning, keeping Wei Wuxian, the both of them out of trouble.