Generally he trusts Wei Ying to handle his own, so when he sees the pan being thrown, his ire turns towards whoever threw it, as he feels overprotective, and he moves to attack that person, but then--

--But then Wei Ying stumbles onto the side of the ring and Lan Wangji rushes to catch him.

"Let's leave," he murmurs gently into his ear, placing an arm around his waist.