Black Market had an actual player character, all the staff was your harem, and any "normal" girl that spend too much time with you ended up with a growing title from "player's company girl" to "player's bitch", Monster black market had something similar, the entire staff could be himnotised to be your harem, while in Black Market you had to out-purchase the boss's territory and he would tell you he was too old anyway, I think that gave you the boss's girl or something, the reverse also happened, if you lost, your main girl was raped by the boss, that's what I consider actual NTR in brothel games