I rescued a pregnant female cat from a mall parking lot. I kept two of her kittens. One of them was a female. She came on heat very young, before I could spay her, and had four kittens. I kept two, brothers.
One lived about 17-1/2 years and the other to within days of his 19th birthday. Both went down with kidney disease. I nursed both of them longer than I should have, including daily subcute fluids and epogen injections. (I would advise against epogen for a variety of reasons)
It is pretty tough to see our little pals go down after so long with us. My memories of their end days sometimes cloud my fuller & happier memories of the many years they were healthy and in good spirits. In general, though, I say that God must surely love both people and cats to have put us together.