Seduce to Revenge: Tame Her Almighty King

Five years ago, my adopted sister framed my family and left my parents to die in exile. Now she's Queen Aurelia, married to King Bastien. A prophet says I'm destined to bear the heir she never can. So I'm entering his palace as the King's Vessel. I'll win his heart and take everything she stole from me. But why does a mysterious storyteller say the King crowned the wrong woman?