Those and lions are the only cats known that don't mind to tolerate friends and non relatives around in their territories, cats clearly enjoy the company, form hierarchies and share food. Hyaenas and mongooses are related with cats and definitely social also. Lingsangs on the other way, are solitary.
They don’t go outside (they can’t really, it’s too busy by the road here and they’d decimate the wildlife, but I live with it because ultimately we’re doing them a huge favor by giving them a home, post-rescue) so I am sure that has something to do with it. Perhaps infantilism is keeping them in this pack headspace? But even then my mother’s cat — rural, murderous, tough tabby tom — treats her like a god and the rest of us as an annoyance.
They antagonise each-other most of the time, but they also support each other in times of stress. If one goes to the vet and the other doesn't, the initial reaction is hissing and being a dick. Then, after a few minutes, it's licking and comforting.
I don't like to anthropomorphise too much, but they definitely look out for each-other. Equally, they definitely annoy each-other.