It was a Tuesday, the kind of gray morning that makes the whole world feel like it’s wrapped in a wet blanket, and Charlie was supposed to be napping. He was four years old, a golden retriever with a coat the color of summer wheat and a soul so gentle it could melt a stone. But on that Tuesday, he wasn’t napping. He was staring at the back of the couch like it had personally insulted him. I was half-watching the rain streak down the window, my mind somewhere between a work deadline and the grocery list, when I heard a low, thrumming sound. It wasn’t a growl. It was something deeper, a focused vibration of energy. I turned just in time to see him back up three steps, his massive paws splayed on the hardwood floor, his haunches sinking low like a sprinter in the blocks. His eyes, those warm, amber pools, were locked on the target. Then, with a grunt that seemed to come from the very bottom of his soul, he launched himself. It was physics-defying. A 75-pound golden retriever, generall...