I have had cats basically my entire life. But my current cats was the first time I had 2 cats from the same litter, and it has been amazing. The difference in how they interact from any of the cats I have had in the past is amazing.
In the future we plan on trying to stick with cats from the same litter and not separate siblings if possible.
But you're probably relying on them for rodent control, right? As a rule, I think all cats should be indoors, but this is a case where it's not so bad if some people get exceptions. Presumably there's plenty of wildlife habitat where small critters can escape your cats without getting in your house!
Why?
The notion is that they teach each other not to fight so rough, which is something. We are bad at teaching them. Most of the orneriest little shits I’ve known were singles.
I had one cat that was a single kitten from a feral mother. She was a spitfire. Loved kids, and me, and everyone else could fuck right off. Except my girlfriend, but only on Tuesdays. She had a special hatred of vets. She would probably have lived 2 years longer if she didn’t turn into a wolverine at the doctors office.
You immediately escalate, make a new loud noise, and perhaps bop them on the head, then walk away. Domestic animals are smart enough to know that this means they crossed a line. Do a consistently and the line becomes very clear