What kind of childhood did Joe have?
Joe had a horrible childhood with an alcoholic, abusive father who regularly beat his mother. His mother took Joe and ran away several times, but his father always found them. Despite the fact that his mother had worked hard and prayed for a better life for Joe, they could not escape the abuse until his father died in a fit of rage. Joe was never able to get an education because he was just trying to survive growing up. Now as he is married to Mrs. Joe, even though she is also abusive, he sees her more in light of his mother rather than his father. He feels sorry for all the hard work she has to do around the home and forge and that he cannot give her the life she wants.
Joe, much like Pip, has had a difficult childhood. The abuse from his alcoholic father makes Joe have a special tenderness for Pip, and this is probably the reason he married Pip’s sister. Joe’s education also suffered during his youth resulting in his inability to read and write. The knowledge of Joe’s past causes Pip to have a new admiration for him.