Lan Zhan looked too old, sometimes, staring into the blinding sun of dawn. He looked like he had gone somewhere Wei Wuxian couldn’t follow, beyond the scope of the horizon. Resentful energy swirled black and terrible at that thought, and Wei Wuxian laughed it to shattering pieces. Lan Zhan had stayed, but that didn’t mean he would forever.

The resentful energy occupying Wei Wuxian's body like an enemy army is very interested in giving him Lan Wangji, tied up with a bow. Wei Wuxian is hoping that Lan Wangji (who is far too noble and very keen to save Wei Wuxian's misguided soul) doesn't find out about any aspect of that.