Uninvited guest
Fu Shu Chang did not want his family to see this hideous side of him, he was worried that his family will start treating him differently if they were to find out that every full moon he has to rely on human blood to survive. Even though Fu Shu Chang never harmed a human and only brought the blood from the blood bank, the fact alone that he had to drink human blood for the sake of survival was enough to make anyone feel disgusted with him.
He wanted to ask for Song Yan's help but then he would have to tell her that Chen Chu Chu slipped into a demonic creature inside him. That's right, the thing inside him was not a ghost or curse, it was a demon and that too one whose cultivation level was very high, it could easily hide its presence from others and even suppress his presence until Fu Shu Chang went against the contract.