When Magnus' tension drains away, Lan Wangji takes the opportunity to rearrange them, pulling Magnus more firmly onto his lap so they are not sitting so awkwardly. He does not let go.

"Mn." In this, he means both approval and mild interest. Magnus is welcome to tell him of the things he likes, or not. Lan Wangji can sit in silence without objection. He will hold onto him either way.