Cersei Lannister : Margaery has her claws on Joffrey. She knows how to manipulate him.
Tywin Lannister : Good. I wish you knew how to manipulate him. I don't distrust you because you're a woman. I distrust you because you're not as smart as you think you are. You've allowed that boy to ride roughshod over you and everyone else in this city.
Cersei Lannister : Perhaps... you should try stopping him from doing what he likes.
Tywin Lannister : I will.