So, Lan Wangji got drunk and marked himself with the Wen iron.

The obvious connection is that now he is marked in the same way Wei Wuxian was marked, but going further?

Lan Wangji’s adopted son is a Wen, for which the name of the family should not be a matter of shame but a matter of pride.

So, close to his heart, Lan Wangji also has a symbol which represents his son.