But they are not literally slaves, aren’t they? According to the novels, they are the daughters of some government officers, although idk about Consort Liu because she was given by the first prince. Even if she is taken from a brothel, I don’t think it’s appropriate to call her a slave. Even in the novel, the wangfei called himself slave/subordinates, isn’t it just a name because they don’t have the equivalent word in English to represent someone lower and somehow being the subject of the king/royalties/nobles? I have the word in my language because there is this similar system as well to differentiate how these commoners can call themselves in front of a king, but actually the word slave itself is, in my opinion, rather incorrect. The dynamic between the royalties/nobles and their subjects are quite different between western cultures and eastern cultures. Just my opinion.