It's more explained in the novel but her aunt hires an assassin from her secret mercenary group she runs? or supports? Idk I don't remember that part but yeah it's her aunt who sent him to kill the princess and seeing how composed nia was she already had done this several times
i have no idea what is happening did the FL plan this?? or is it her aunt?? ٩(๑❛ᴗ❛๑)۶