I have two - one is remote, aloof and probably wouldn't notice I was gone.
The other is affectionate, cuddly, always wants to sit on my knee and cries on a night when they get locked in the living room.
Personality wise complete opposite ends of the spectrum.
I've had cats all my life. I would say it all depends on the cat. For some cats there is nothing worse that having another cat in their territory but some are more social.
I've had older aloof cats come to life, perk up and become more social when there is new social cat in the house.
surprisingly, he became solemnly composed and accepting of her almost immediately, despite spending his whole life trying to dominate his sister (out of both competitiveness and territoriality, i imagine). i picked her from the kitten rescue specifically for her mild temper, knowing how dominating and insecure he could be. she was playful but respectful, and i'd like to think he was a little less lonely in those last few months with his sister already gone.
fast forward a couple years, and i have an accidental (male) foster kitten who's a crazy ball of energy next to my mild-mannered, now-adult cat. otherwise pretty lazy, she's learning how to play more energetically and socialize with the little devil (as i socialize him as well--his first-time cat owner didn't seem to know if or how to do this).
so yes, there's some osmosis going on, as cats learn from each other and the social structure shifts, but it's limited. no wholesale changes in my experience.
We got another dog to teach our first one how to be a normal dog and keep her company. Dog #2 was a rescue that had grown up on the streets. He was good about eating food but never learned to not pee inside.
We ended up with two weird-ass food-disinterested anxious dogs that pee and poop indoors.
Ouch.
If you fall to the floor dead, your cats will eat you before they are starving. Dogs will wait.
I view this as practicality vs. sentimentality. I'm not sure which one I prefer, but I hope it is an accurate measurement of animal behavior.
Often, wait to starve to death.
"Your faithful golden retriever might sit next to your dead body for days, starving, but the tabby won’t,” she writes. “Your pet cat will eat you right away, with no qualms at all. I’ve seen the result.”
https://nypost.com/2014/08/03/a-million-ways-to-die-in-new-y...