Claudius understands enough to paint a picture in broad strokes, colored by the painful circumstances of Lan Wangji's own seclusion, and a knowledge of the hurts that make a man retreat from the world. He also understands Lan Wangji long loved a mother kept behind closed doors -- a mother who teased him, who smiled even when he bit at her, because he felt so much and she knew how much her son's heart could hold.

Lan Xichen must have seen his brother's devotion every day Lan Wangji waited outside that closed door. It must've been a dear hope of his, not to let Lan Wangji’s devotion go to waste. I think I've spent most of my life worrying about you.

"It must've been a comfort to him," Claudius says, with a softer smile, “to see thee well-befriended. Such selfless people never stop worrying about the ones they love, even when they’ve their own sorrows to bear.”