There are a few cats in my house that I don't legally own. Jackie is one of them. She came in as a foster with her sister and I was never able to come anywhere close to taming her. And there is also an extreme lack of feral cat colonies to relocate cats like her to.
So she lives here. But we don't own her. She's technically in the custody of a local rescue.
She has free reign to go outside whenever she wants through the cat door and come in whenever she wants. Every once in a while we will have to trap her in the bathroom to give her any worm medication she might need.
It's rare for me to see her on this side of the house. As soon as she sees me seeing her she runs and hides. My wife tells me that she can give her a little bit of petting as long as she's filling the food bowls.
Otherwise she is a ghost cat. A thing normally seen out of the corner of your eye. Not something you observe.