He does not stop the slow, gentle petting until he is sure that Wei Ying is asleep, his breathing deep and even.

Only then does he stretch one arm enough to snag the edge of the coverlet, just barely in reach. He drags it back up and over them both, hoping to ward off any chill.

That accomplished, Lan Wangji puts both arms around Wei Ying, holding him close, and allows himself to drift back into slumber once more.