I have only one cat, and I understand your concern. I often think that Fister gets bored, but I really can't tell. At least I'm home with him most of the day. The times he's been around other cats, he's hissed and growled. The old male living in our back yard, he used to chase out of the gate when he was little, but now they just ignore each other. LOL!

Some cats are probably best off being only cats.