It's the little things I miss the most. The way he'd pop his head up and look when he heard my voice, or his very distinctive whinny. Little incidents that showed his character.
Recently I remembered being out in the field with him one spring - memory says it was the first or second spring we were together, but I couldn't find it in my journal entries. I had taken a shedding blade out to do some spring cleaning on the boys. My QH was very nosey about the shedding blade and kept turning his head to see what I was doing. I held the blade out to him and he sniffed it and then gently took hold and lifted it out of my hand. After waving it around a bit he dropped it and turned his head back to me. I don't remember exactly what I said, but the gist was an offended "Hey! Pick that up and give it back to me!"... and he did just that!