[it will certainly tell them something, whenever one of them realizes first that Lan Wangji knew all along while Wei Wuxian was oblivious to that fact. it seems so self-evident to both of them that their current versions of reality would be the obvious truth.

Lan Wangji does have one extra tally in the "Wei Wuxian knows I know and is going along with it" column that may not be immediately obvious to Wei Wuxian, though. it's clear (at least in his mind) that Wei Wuxian is acting friendly towards him right now as just that, an act -- part of their joint effort to sell that Wei Wuxian was uninvolved with the previous escapee. if Wei Wuxian was trying to act natural, Lan Wangji would expect for consistency's sake that Wei Wuxian would judge this sudden relative affability as more suspicious to Lan Wangji than refusing to talk to him at all.

the idea that Wei Wuxian, given insufficient time to process how to handle a situation, might not default to hostility towards Lan Wangji at a basal level is something that perhaps neither of them have fully internalized yet.]

...

Know little. Saw little more. His face was hidden.

Left my sight after entering the alleyways.

[it's all, strictly, accurate.]