What kind of man did Alexandra marry?

Scout describes Uncle Jimmy as a man who "never spoke a word to me in my life except to say, 'Get off the fence'". Uncle Jimmy said nothing and Scout had no interaction with him. It didn't seem like Aunt Alexandra had much interaction with him either. At one point she asks Aunt Alexandra if she will miss her husband when she visits and Alexandra says nothing. Scout concludes that, "Uncle Jimmy present or Uncle Jimmy absent made not much difference, he never said anything." We never really find out if there is more to Uncle Jimmy than Scout notices, he is just sort of there in the peripheries.