Zeus didn't hear any of the exchange between Poseidon and Highways. He was only treated to the joys of the visual - a bit like in a silent movie. Seemed to be serious business, too. The last time he'd seen Poseidon like this was when... Well, he couldn't remember. A long time ago.
When it was over, he was kind of disappointed that it didn't take longer. There was just a bleeding man on the ground and nothing else. "You've lost your touch, old man," he said, flicking the butt of his smoke out the window and started the car.