Cat #1 was an 'accidental cat'. She turned up at our back door one icy cold evening, and I couldn't leave her out in the cold, so let her stay overnight. I sent DH to the local shop to buy some chicken for her, as we're vegetarians, so had no meat in the house. She turned up the next couple of nights as well, which was fine, as we needed to use the chicken up. 
I took her to a vet, she wasn't micro-chipped, so I asked a few neighbours and someone recognised her as belonging to a couple who lived in a neighbouring street. I went and knocked on their door, the guy answered and I said to him, "I have your cat here," and said where she'd been the last few nights. He said to me, "she isn't happy here, she doesn't get on with our other two cats, you can keep her if you want," and shut the door! That was ten years ago now, and she's still the boss of the household.
Up until recently, the other cats who lord over this house, have been adopted from shelters.
However we moved house in November 2018, and just after Christmas, a very persistent cat turned up at the door. Took her to the vet, she was micro-chipped, and turns out she belonged to the previous owners (who have moved abroad). I contacted them, and the woman told me that they'd made plans to put her in a shelter, due to the move abroad, but she hadn't returned home for the last three weeks before they moved out. She told me they'd feared the worst, as she was chipped, and no-one had said they had found her. "Take her to the shelter," she told me, "and explain she turned up." Yeah right, like that was going to happen. Instead, we simply changed the owner's name to mine on the microchip registration, and now she's back in her home where she belongs, just with a different set of humans to treat with contempt!
DH has said that absolutely no more cats are allowed in this house, but even he knows, were another one to turn up at the door, that once they claim ownership of you, that's it. There is no choice on the part of the human/s.