Can you accept Grandpa as a moral character? By the end of the book we have been well conditioned to accept his explanation of "ask and ye shall receive" and we have seen many good things he has done. But...
We know he desired Miss Love long before his wife died, he refused to stay home when he was sick because of it, and did not in any other way act on his feelings.
Can you forgive his initial actions? Do they need to be forgiven (did he do anything wrong)? Does your answer affect how you view his other actions in the book?
