We have three and they are best buds, but they have been together since birth, never seperated, and sometimes they fight, but it's never bad. It really depends on the cat, sometimes they will get along but sometimes they won't. You need to introduce slowly. Sometimes it takes a long time and they may never get along. Sometimes they will just tolerate each other. If he is older it may be a little harder to introduce. We watched a friends cat for almost a week and I tried introducing them properly, but it never worked when they were together the new cat wanted to sniff them but our cats wouldn't have it. So they would just sit or lie there and hiss and growl, they never fought or anything. So I didn't try, since we weren't keeping her. I miss her though, she stayed in my room, and she slept on my chest or neck every night.
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