My protagonist meets a Queen who is incredibly beautiful, acts very flirtatiously and is naive on most topics despite the fact she is a young adult. In short, she fulfils every stereotype of what a poorly written female villain usually is (sexy, wears revealing clothes, motives are probably to do with a man who broke her heart, little to no real personality). However, later in the book, it's revealed that she has been the mastermind for the entire plot, influencing everyone without their knowing. Her entire persona changes and it's shown that the 'naive young woman' was just an act. She is actually cunning, cold and fully aware of how to use her sexuality as a weapon, as well as making it clear that the mind is the more powerful weapon than the body.
Thing is, I don't know how to effectively hide her from the readers whilst also insinuating and foreshadowing she is more than she seems. Also I don't want her to be perceived as a poorly written character. I want the readers to see her as an interesting person, analyse her and write her off as a threat instead of going "Oh no, another author has written an overly sexualised woman with no clear personality or motive."
How do I go about doing that?