The knock on the door is out of courtesy, but Lan Wangji has no intention of waiting to be invited in. He only waits a couple seconds before sliding the door open.
He doesn't need to even get a good look at the figures together on the bed before he freezes where he is in shock.
Re: belated CW for anyone stumbling across this, UNDERAGE SMUT WARNING
Or perhaps he would.
The knock on the door is out of courtesy, but Lan Wangji has no intention of waiting to be invited in. He only waits a couple seconds before sliding the door open.
He doesn't need to even get a good look at the figures together on the bed before he freezes where he is in shock.