The Untamed S01 E33 Episode 33

"I can stand pain but I can't stand seeing you in pain."

Wei Wuxian's previous life is ended by jumping from the cliff. The scene changed to after 16 years later. When he wakes up, he finds he's lying on the bed in Gusu Lan Clan. The next day, he finds out something strange on Lan Wangji's body. What would that be?