Ares made a lot of people do a lot of things - most of the time, they didn't like him for it. He wondered if it was the same; if he'd been the same careless gorilla stomping around on everyone's lives the way the gods did, playing games that had consequences he couldn't care less about.
"I don't know you," he said, in the same artless, simple and true manner the man was speaking to him in.
Not knowing most of the time came with not caring. Ares couldn't claim to be the type who cared - perhaps in this case he did care, even if he did so only because he wanted to shoo him away and be left alone.