Another poster's question about getting a dog reminded me of how much fun my cats are. Last June, my old lady (16ish) was diagnosed with kidney failure and given a prognosis of about 3-6 mos. We were giving her subdural fluids, meds and a special diet. Around the same time, a feral kitten took up residence on and under our deck, and began responding to me when I meowed to (her?) In the fall, we trapped her, for the purpose of trap,neuter, release, but ultimately, I invited her in, and she has been here ever since.
My older cat is going strong. Her kidney function is holding steady at just a bit impaired. We stopped the fluids, she fought three adults so strenuously it just seemed that her quality of life was affected. The new cat ADORES her, wants to play, snuggle and lick her, but to no avail. She is tolerant, barely, her hard smacks on the nose of the intruder have given way to annoyed shoves with that declawed paw. Of course, the new cat has huge, sharp claws which she sheaths. Old lady is the boss, no doubt about it.
But the biggest change was when we went on vacation. We were gone for nine days. A neighbor or relative checked in each day. New cat hides whenever a stranger comes in, she becomes completely unnerved at the sight or sound of any arrival, even if they just pull into the driveway. Lady isn't overly friendly, but she does come to say hello. In the past, whenever I've been gone, Lady has been visibly upset, tramatized and angry at me. Not this time. Both cats were happy to have us home, vocal and attentive, both attached themselves to me, literally, Baby sleeping on my head for two days, but Lady was considerably less stressed.
It's odd. They are obviously "people" cats, but there is a clear recognition that they are CATS. They watch each other and often repeat the actions of the other. They share food bowls, nicely, no arguments.
They are great companions. They have won the heart of my formerly cat hating husband so much that he has insisted on an architectural change to a recent home improvement project. For the cats.... 
