] He blunders around so much with his sisters that I wonder if he must always be this much of a dolt with everyone he knows? Maybe this is the reason he is so solicitous to Fanny--because he's always putting his foot in it somehow.

I agree, he seems completely unaware of how stupid he sounds. But in Chapter 1 he is described as a steady, respectable young man. I thought at first that this was inconsistent with his later treatment of his sisters. But then it occurred to me that although he's not sensible, he is steady - steadily and consistently miserly and stupid when it comes to his sisters. But could he be described as respectable if he acted this way around everyone? Or maybe he's only respected by other foolish young men. :-)