I'm posting this picture just because really-new-cat Irving looks so silly lying like this with his back legs stretched out. He was just zoning out.
Yesterday we took him to the vet, who says he's 7-8 months old. He's on antibiotics for his cold, and we'll take him and slightly-less-new-cat Halley back in three weeks to get neutered and spayed, respectively.
Still no idea where he and Halley came from. It's especially odd that he was on our back deck, since it's really not easily accessible, and there's no real reason for a cat to find his way there. I wonder if we'll ever find out?