Male or female?
If female, she is going to go in to heat twice a year. If she is not successfully mated, she will go in heat every 1-3 weeks. I know of an unspayed female cat, kept indoors with her spayed brother. As long as I knew that cat she was in heat; ragged, skin and bones, and yowling constantly. Her brother followed her around everywhere she went.
http://vetmedicine.about.com/od/pregnancybirthincats/f/Cat_estrus.htm
If male and kept indoors, he's going to mark everything in sight. If male and kept outdoors, he's going to get in to fights. Not to mention siring all sorts of kittens and exposing himself to feline diseases.
We don't have a stray pet problem here in the wilderness. If a cougar doesn't get them, a coyote or an eagle will. Last fall a young cougar was found hanging out at the cemetary, with a stash of domestic cat carcasses. Sadly, the cougar had to be put down. He was beginning to treat the town as his personal larder.