Peter has become increasingly more loving to Aaron as Aaron has gotten older and more responsive.
He loves to "hold" his brother, give him kisses, and will even help me when Aaron is crying.
The most common means of help is putting a pacifier into Aaron's mouth (I think he learned that from seeing me to it to him).
However, he has also started rubbing or patting Aaron or the arm or stomach and holding his hand to calm him down.
I haven't gotten many good pictures yet, but trust me when I say it is the sweetest thing and there is absolutely no regret for having my babies so close together in age when I see them interact!