We were, as you might expect, somewhat taken aback.
The vet went off to contact the cat chip registry people, and we spent ten tense minutes wondering if we were going to have to give Buddha up, who the owner was, and if they'd give us hell for having him neutered (flame point himalayans are quite valuable among people who care about such things, and they might have wanted to use him for breeding). The main thing we wondered was what sort of person it was who'd left him on our doorstep, FIV+ and totally unused to being an outdoor cat.
Turns out the chip was sold to a pet distribution company back in 2002, and then never registered.
So the mystery remains unsolved. But now we do know that Buddha used to belong to somebody.
Anyway, we got more antibiotics for him, and some goo to smear in his eyes to help reduce the cherry, and they're going to run blood tests to double-check the FIV diagnosis, check for skin mites, and a few other such things. The vet recommended we give him 3/4 dry food, rather than the diet of almost-exclusively wet food we've had him on.
My eyes and throat were much better this afternoon -- almost back to normal -- and then we went into the vet. Now I'm in the worst allergy hell yet. Oy. I hope I can see tomorrow. -.-