What About You?

“Hanguang-jun, don’t make my sacrifice worthless.” Jiang Cheng pleaded. He’d already had one brother do that to him, he wasn’t sure if he could bear another doing the same thing. “You have to leave me here.”
Lan Wangji looked him directly in the eyes as he said, “I’m not leaving you.” 
“You have too!” Jiang Cheng tried to raise his voice, but it came out weak and pathetic, so he tried again. “You can’t die here!”
“And you can?” Jiang Cheng was shocked to find that Lan Wangji sounded genuinely angry.
~
(Jiang Cheng sacrifices himself for Lan Wangji and almost dies, but in turn saves Lan Wangji's life. Jiang Cheng just doesn't understand what Lan Wangji is so upset about.)