I went through something similar with dad before he died! The only one who he showed respect for was his older brother! After Curly would leave he leveled out for awhile! Around the rest he was an ass! I talked to my uncle and ask him, why he thought dad always treated him different! He said after WW2 , three years in the south pacific, dad was always different! I believe he had what today they call, PTSD! Curly always brought dad a treat, turned out Curly was feeding him thc cookies,cake and goodies! When I confronted him about the treats. Curly said he gave them to him, and never told dad what was in them! Because he wanted his younger brother to have a happy life! I'm not suggesting you give him cookies, but you might talk to your mom, about anything that might be a trigger for his actions. Something from years ago might be his problem, and has gone undiagnosed for years! I'm sorry for your dads problems, and hope your family gets a grip on thee situation!
