Somewhat relevant, but not terribly spectacular:
We adopted a juvenile cat (about a year, according to the vet) whom we found skulking about the house in mid-summer. Or maybe he adopted us, I dunno. Underweight, but otherwise in good health, we had him neutered and got him his initial set of shots. We believe he was dumped, as he did have a healthy dose of "attytood".
Fast forward about 10 years, and he's about as happy and feisty a cat as you're ever likely to see. Mellowed a bit in his old age, but still ornery. Good mouser too.
You can't save them all, but you can save one or two and help out otherwise by supporting - financially where possible, with food, detergent and linens when money is tighter, and/or with your time and energy as a volunteer - local no-kill shelters and the local ASPCA.
PSA over. Good luck with your friend, Aaarg.