Life force was sucked.

"You can't!" When Xiao Chuxia heard that Yu Yue was talking about moving Yu Fei, she immediately panicked. She said to Yu Yue, "If you move him now, then it will be really dangerous." 

"So you know it's dangerous!" Yu Yue sneered at Xiao Chuxia. "I thought that you were unaware of how dangerous it is to fall from a cliff. Why did you let my brother go up the mountains? Where were you then!?" 

More importantly, how could such a thing happen to her brother? Yu Fei was not an idiot. Why would he go to the mountains and that too at night? 

Yu Yue was certain that there was something more to this incident. 

Yu Dong had the same thoughts. Why would a mer who goes up the mountains for no reason? Was this really just a coincidence, or was it a man-made injury?