Yes, you would like 2 and 11, wouldn't you? :P I figure that Harry was much closer to Bob than he was to Justin even before the whole 'I killed your Father' thing. Just from his behaviour in the flashback in "What about Bob?" when he first arrives back home. He seems hunched and nervous, like he's afraid he's going to be in trouble. It makes me think that Harry always found Justin intimidating. Also, I imagine Justin was off doing things a lot while Bob couldn't leave the house, so he was always there.