I don't agree with what Harry did at all. He promised the mother that he would protect the kids, that doesn't mean taking care of one and ignoring the other. I'm sure if Harry did something...anything at all..Brian would have turned out differently. Sure he was old and he probably remembered what he saw, that doesn't mean he didn't deserve a chance to live a normal life with his baby brother. He was a little boy when it happened..it's not like the next day he went and started killing people. I'm sure if he had a father figure like Dexter had, he would have been fine..or at least a better chance than what he was given.