"Lan Sizhui," Lan Wangji corrects himself. "A Lan disciple. I have mentioned him to you." It's nearly the most evasive answer possible, which is objectively ridiculous. In this setting, he could as easily say Wen Yuan, who became Lan Yuan, who became Lan Sizhui, the only living remnant of everything that Wei Ying once stood, and ultimately died, for and suffer no consequences. Protective habits are not easy to break.