[Lan Wangji will bow in return, very polite, not trying to keep him. he doesn't think Chongyun will get far down those other tunnels either, but he's glad that someone else is keeping an eye on all of this -- even someone outside his own faction.]

Mm.

[he has a feeling he'll see this youth again soon enough. and in the meantime...]

...

Be careful.

And, good luck.