We did TNR with five cats. A few weeks after their release we brought them indoors, as they were being threatened by a couple of raccoons. They’re the most loving kitties we’ve had. This, after the lady from the local feral cat group said, “You’ll never tame them.” they wait in line to sit on our laps and cuddle.
We lived in a house in a neighborhood where a feral cat kept having kittens, two litters per year. Our neighbors had tried unsuccessfully to trap the cat. Eventually, I borrowed their trap and set it up in the back yard. The feral mom was smart enough not to trip the trap, but her son bounced right on the trip plate. We took them to the vet and had them fixed and vaccinated, then released them. A few days later, we caught one of the other kittens, and I decided to keep it in the house. Every day, I would try to show her that she was safe with us. We caught the other girl and put her with her sister. Last, we recaught the boy.
Of the three, the boy became so tame that one would never guess that he was feral for his first four months. The girls never became that tame--you could pet them, but not pick them up. One of them would roll around on my feet whenever I was wearing socks. Unfortunately, that one died of lymphoma a year and a half ago.