This quote from the novel will explain everything (Chapter 93)
For a moment, Xie Zheng felt like he wasn’t himself anymore. He couldn’t control his body. He saw himself lower his head and, through her clothes, bite her shoulder fiercely.
Fan Changyu cried out in pain, but his teeth only clenched tighter. His phoenix eyes were filled with a bloodthirsty look. His arms locked around her, not loosening a bit no matter how she struggled, like a wolf biting its dying prey.
Fan Changyu cried out in pain, but his teeth only clenched tighter. His phoenix eyes were filled with a bloodthirsty look. His arms locked around her, not loosening a bit no matter how she struggled, like a wolf biting its dying prey.