Good point about his father zigbot, I'm sure he has regrets about the situation with both of his parents. Why couldn't David provide safe private care for Terry? My opinion is that he just had a real hard time dealing with mental illness. I'm sure he regrets letting so much time pass when Terry was struggling. He seems to be quite remote at points in his life. It must be terrible to find yourself in much better shape emotionally, and look back at mistakes you have made. Of course Terry was not David's ' reponsibility ', but he was family, and David had the means, if not the will.