Stop That, My Vampire Commander summary:

Li Lingtong, young lady of Prime Minister, was reduced into a daughter of a criminal, deprived of the title of Would-be Crown Princess and demoted as a maid serving in her relative’s mansion. Her childhood sweetheart has been being far away on the frontier, her dear father holding in custody and her younger brother missing… What’s worse, she was sold to Gong Simo, a super powerful eunuch second only to the monarch. Li Lingtong had thought that the psycho eunuch was going to abuse her, but he treasured her in captivity, beseeching her to feed some blood from time to time.