No pets??!! Anne, I can’t imagine a life with no pets 💔 Yes, personalities, gender, and age matter when you have more than one pet. When we adopted our second male cat, we knew 2 males, even neutered ones, may not be compatible. But, we also knew the male we had is not aggressive by nature and has a very accommodating personality. The two cats had one initial tussle and a few days of distrust, then accepted one another. But, our second cat would not accept Miaow. His personality was dominant and he did not want to share his domain.
Dogs are the same. Our Pekingese didn’t particularly like other dogs, but he was not even slightly aggressive. We were able to adopt 2 dogs and he simply ignored them. Now, he and one of those dogs have passed. The remaining dog, Syau, would be very reluctant to accept a new dog, so she will probably remain our only dog.