The late great Mr. Max was a solitary cat. I often thought about bringing in another cat into the household when Max roamed the halls (and rooms) especially the last few years of his life when I wasn't around much. But given that whenever we took a walk and Max would spot a cat blocks away and hiss and get his hackles (?) up, I thought it would be more stressful than companionship to try and introduce a friend into his life.
Now Max is probably rolling over in his urn given the population of cats that occupy HIS house.
I sometimes wonder how Theo, Thompson, and Diego-san would do on their own in a one cat house. Thompson dotes on the other two so I think he wouldn't be as happy. He often takes his cue from Diego- waiting to do something until he sees Diego does it first. Theo lived in a house with seven other cats before moving in with me and the boyz and he constantly is pestering the other two to play.
Diego-san I think would actually enjoy a few moments alone. There are times he just craves my attention and now that Theo follows him around like a little shadow Diego spends much of the day seeking a little peace and quiet. He's such an impressive looking cat I'm sure he would have had no trouble finding a house that would have gladly accepted him and lavished him with all the attention in the world. But he and Thompson got along so fabulously in their "foster home" that the shelter I got them from wanted the two to be adopted together. I'm forever grateful they did.