Responses
Commonly in an empire exist an empress which is the main wife of the emperor if there is a queen in it,it is practically a concubine (other wife/ mistress) what they do is assist the empress in their task... From what I know the emperor selects the empress on who is the one that can first give him an heir.. well I don't know if it the same in this manhwa but that is basically it

Waitt... Empress?! So you mean the prince' another wife? Because I am sure that's not his mother.. LOL (but if it's his stepmother, then that would make sense)