I think it is interesting that JA indicates that John was very young when he married Fanny and "very fond of her." In spite of what we might think of the characters, it suggests a genuine affection between the two. Was the affection and fondness based upon a mutual love of money and material things, or was it a sexual bond, or ?? That John is rather weak minded when it comes to Fanny is apparent. Film versions make Fanny into an unattractive shrew, but I am more inclined to think that she was pretty, as well as shrewd and manipulative. That she was cold-hearted to outsiders is apparent in that her mother-in-law and sisters-in-law disliked her thoroughly, ever before the death of the elder Mr. Dashwood.