Claudius laughs, both from fondness and because he does fear breaching etiquette an inordinate amount -- it feels natural, that Wangji should provide that education for him, the way Wangji taught him how to use chopsticks. He must have started thinking of Lan Wangji as a brother, even back then.

But that's a conversational layer. He starts navigating layers of actual fabric, removing his dressing gown to clothe himself in the zhongyi, unselfconscious as he does so. He also reveals a lot of marks left by Galahad, the rows of roses and peonies planted along his neck and chest.