Eddard

In this chapter Ned is currently captured setting in a filthy cell in the dungeon of the Red Keep, during his time alone Ned has time to reflect and feels guilty for the dangerous position he put his family in as well as the death of his loyal men. Varya informs Ned about how his family is doing on the outside, he also give Ned an ultimatum of sorts giving him two options. He can admit that he is guilty of treason to the king making him a trader or he can choose to stay loyal to his duty and tell everyone that Joffery is not the true heir to the late King Roberts thrown. If Ned chooses to admit he is a trader it would go well for Sansa and keep his family out of harms way.
I chose this chapter because it is a key point in the story and Ned has a huge decision to make if he chooses to say he is guilty it's almost curtain death but he will be saving his family. If he doesn't Joff will have to kill him anyway to keep him quiet.