My Wednesday walk: Brotherly Love

I have noticed for the past several weeks my youngest son has been very temperamental. Some call it the terrible twos. He's four and I am not sure what to call it now...he gets angry when he does not get what he wants whether it is food, toys, books. etc. He picks on his big brother who although is six years older, does not fight back against him. His brother instead tells him "I love you Brother