We've been noticing some very small kittens near an empty house in our neighborhood. Being the kind souls we are, Spencer went to try to get the cats to see if they were okay. Yesterday, he came home with one of them. He handed it to me, it gave a weak mew, and then basically went unconscious. I thought it had died. However, after a few hours in front of the fire and a few droppersful of water, Lucky revived. It is now lying in front of the fire (again), having used the litter box a few times and eaten our cat food. Our other cat, Achilles, is not impressed.
We (mostly Spencer) have been over to try to get the other cat (which we have preemptively named Hobbes), but it's faster and less almost-dead. Also, it doesn't want to be caught. Have you ever tried to catch a cat that does not wish to be caught? Not easy. So we've left food and water, and maybe Hobbes will survive. Lucky seems to be doing great, though.
I'm not sure about Lucky's future, but she's making herself at home for now!