] Selfish, selfish John is not simply Fanny's puppet. They are two of a kind, and the conversation in ch 2 is engaged in -- not for the one to convince the other -- but rather as a discursive device, so that they can do what both want to do, and John can feel better about it.

Selfish, cold-hearted John didn't need to be persuaded by Fanny to do nothing for his sisters and mother. It's something he didn't want to do in the first place. He needed Fanny to justify his lack of assistance for them. He's not smart enough to rationalize it for himself. He needs Fanny's shrewd, calculating intelligence to provide him with the reasons not to act. By knowing Fanny, and running the idea past her, he was begging her to tell him how to reneg on his promise.