My first kitten, when I was 6, was sort of found by my grandma, his mum was a feral that lived on the farm grandma worked at, she'd been feeding mummy cat since the day the kittens were born and 4 of the kittens decided to start coming over to pinch food off my grandma when they were 10 weeks old, so she brought them home, she kept 2 and mum took 2, 1 for me and 1 for my brother, the other 3 adapted to be domestic cats pretty well but my boy was still very much feral, he'd let me stroke him but was vicious to everyone else and was absolutely huge for a cat.
Our second cat followed me home from school one day, when I was about 13, we did find her owners but they said she was 3 years old and expecting her 5th litter and it was costing them too much money so refused to take her back
she had her kittens then we got her (and the kittens) done, no more litters and she stayed with us til the grand old age of 18.
She was a very small cat and still looked and acted like a kitten her whole life. My vicious killer cat used to spend hours trying to teach her to hunt in the garden, she sucked at it, so sometimes he'd bring things into the kitchen for her, she still sucked indoors but I am now fantastic at catching a wide range of small creatures and know useless facts like slow worms are in fact really not slow and have eyelids, baby adders however do not have eyelids and will bite you if you stick your arm down the side of the freezer to rescue them.