A big brother who isn't

My son is 2 and a half now. Had my pregnancy gone to term, my son would be a big brother to a 10 month old. This weekend, we bumped into someone I knew, who had a son a few days off my due date. Well my little man went crazy for this baby boy. He left our table, went and sat next to this little munchkin, and proceeded to hug him, play him and was completely enamoured with the little fella. I saw what could have been, what my son would be like as a big brother. He knew exactly what to do, and it was just beautiful to see. I do hope I can give him the opportunity to be a big brother - he would be so amazing.