More complex than that. She was obviously someone's pet at some point. For three years my parents fed her, tried to get some humane organizations to come out and rescue her,but no one ever did. I had always said once I move into a house I would rescue her myself. I have a 10 year old orange / white tabby named Gizmo, indoor-only. I always wanted to get him a buddy but didn't have the room. Finally caught her in October and brought her to PetSmart for a full checkup, ear cleaning, shots, etc. After all that time outside in her own, the only thing she had was ear mites. No fleas, no ticks. I was shocked.
So I started by setting her up in the spare bedroom with her own litter box, her own food, etc... I left the door closed for a good three weeks, always checking on her and petting her. Slowly introduced the two. It took a while. I think she got bullied by feral cats in the past. But they are getting along much better. She realizes he is no threat.
She will now come out of "her" room and walk to the end of the hall when she hears me break out the Temptations treats. That was a major milestone.
But she does spend a great deal of time under the bed back there. A lot of times when she sees me coming she darts under the bed. Not always, but more than I think she should. I am careful not to raise my voice, move quickly, or otherwise do anything to startle her. She won't come out and hang out at all, and it's a shame because there is so much room for the two of them to run around like maniacs. I wonder if she looks outside at all the snow piled up and equates that to: "yeah, I've got it much better now.."