Tony had never had a pet because -- well. His parents hadn't allowed it. He'd wanted a dog when he was younger but got over it quickly enough after the first few no's and the very firm last stern no. By the time he'd been adult and could have done what he wanted, the concept no longer appealed. He didn't have time for a dog, and he was allergic to cats anyway. It'd been wisest to stick with his 'bots.
"How do you know I'm not?" Tony asked, squeezing at Steve's hand despite his contrary questioning. He couldn't help himself sometimes. He'd just declared he hadn't been, but wanted to know why Steve thought he wasn't anyway. Sometimes he was just as self centered and egotistical as the media implied.
He watched the fire-dog run around them, with energy to spare and offered Steve a dry look. This thing wasn't going to leave them. Apparently once they made up their minds, that was it. That's what he'd learned anyway. "I'm not scooping poop."