Some years ago my sister lived in a charming Victorian "painted lady" house (built before and a survivor of the 1906 earthquake) in San Francisco. She owned a cat.
There were two apartments on her third floor.
My sister's cat was a rescue--a tiger-striped toughie male with a missing ear-tip, scars, and an attitude that said, "Yeah? Well you should see the other guy."
My sister named him "Don't Give A Damn Sam."
The other third-floor apartment was occupied by gracious elderly lady with no family to speak of and a cat of her own. Her cat was a very gentle tuxedo named Percy. He was such an aristocratic cat that my sister referred to him as "Sir Percy."
The elderly lady, who had no family connections, sensed that she was near death. She asked my sister to take in Percy when she passed.
My sister hesitated, because of Sam's aggressive character--but what could she say in that situation? She agreed to provide a home for Percy.
The elderly neighbor passed on. My sister picked up Sir Percy from the bed where he had been a faithful companion until the end.
She opened the door to her apartment and placed Sir Percy on the floor--ready to snatch him up immediately if Don't Give A Damn Sam attacked.
The two cats stared at each other for a moment. Then they began to purr and rubbed together. From then on they were fast friends.