Shae from A Clash of Kings is a prostitute that Tyrion falls for. When he comes back to Kingslanding he finds a place for her so that he can visit her clandestinely. His father has expressly forbidden him to take a prostitute as a lover, and yet, that's exactly what he has done. Shae has Tyrion's ear and often gives him advice. Her boldness and frankness are refreshing to him. Later, when the fighting becomes more intense, he has her come to the castle in the guise of being a maidservant.