Because the gods find toying with our lives is entertaining? Don't ask me.

[ who is kara to begrudge her anger, when he's so frustrated with the situation himself? having these powers foisted upon them, and their freedom stolen as they're forced to follow what few leads they have, or let their world fall to ruin... none of it is fair.

and despite his bitterness at being outed as one of the maou, he knows lan wangji means to help. he doesn't deserve the backlash, and certainly not a pool of blood. ]

Check his ears and nose. It looked like they were bleeding, too.