The middle kid seems to have lots more pent-up grievances about things "done" to them, whether it's real or imagined. I'll bet if you ever have the chance for a heart-to-heart with your brother, he'll bring up stuff that happened decades ago that you never gave a second thought to. My brother, the middle kid, who I am very close to has chosen these last few years to rewrite our history as a family. Sometimes I challenge him when he has a memory that I know is false, like blaming other people for his failures, but sometimes I let him get away with it. It can be crazy-frustrating but I think it's his way of coping with whatever is lacking in his world. Who knows?