Sam was a 15-year-old gray tabby with green eyes and an introverted nature. When we got him at the age of five, he had already been declawed. Watching him attack our sofa (I'm not sure he knew he had been declawed) I could understand why. Sam had an aversion to dogs, crowds (as in more than two people in a room at a time), and being held. He learned to tolerate our beagle but not the other two things. We have friends who visited many time but never saw Sam, and until shortly before he died, he would never let any of us hold him without struggling.
He wanted affection, understand, just on his own terms. As soon as I lay down, Sam would come to my side of the bed and demand to be patted. He also liked to be near whenever I was working on a book; I'm not sure if the fact that I was planted in a chair for hours at a stretch made me a convenient target or whether it was the keyboard that fascinated him (he loved to walk on it), but sitting at a computer always seemed to draw Sam out. Of course, usually I had to push him out of the chair to sit down because over time, the chair in my writing room became Sam's favorite spot. The seat of my pants was often covered in cat hair.
Sam was an indoor-outdoor cat when we got him, but with him having neither claws nor a sense that our house was his home, we were reluctant to let him out and so made him into an indoor-only cat. For a long time he tried to get out often. Then, a few years ago, he succeeded and was gone for a week. He returned with no obvious signs of ill health except for devouring food like he hadn't eaten that whole week—probably he hadn't. After that, he never tried to get out again.
He never took to our younger cat, or the dog either. I had to respect him for his "catness," that inner need to please only himself. When he killed a mouse, he didn't eat it, he left it for us to find. If he knew we were going to take him to the vet (and somehow he often knew) he would disappear into another dimension.
A year or so ago he developed a problem with his thyroid and had to go on daily medication. About a month ago he started being picky about what he ate, then not eating at all. We had to stop the thyroid medication since it turned out he wasn't tolerating it well, and then his other problems began. By the end, he was so thin and listless that it tore my heart to see him.
Charles and I stroked Sam's fur while the vet gave him a shot to put him to sleep. Once Sam was out, the vet gave Sam another shot to stop his heart. It was over in minutes.
In some ways, cats have it better than people.