Rivalry among pets can be really intense. Growing up, my sister received a pet dog from her dad despite the fact we had two pet cats, who were litter mates and brothers. When we let them in the backyard, my sister's dog Pooh Bear would come and want to chase one of the cats. Without failure, the brothers would stick together and corral Pooh into the corner of the yard despite the fact he was bigger than both of them. Only when Pooh would attempt to bite did the claws come out. He was a smart enough dog that he only had to learn the lesson once. Mostly they hissed him into the corner. But Pooh was never allowed inside the house because it was the cats' turf. When he was inside, they would chase him into my sister's room. It was intense.
The ironic part was that the brothers had their own dominance games inside the house when there wasn't a dog. Drew, the older brother, was always the more out going cat. He was charismatic and would let almost anyone come and pet them. When strangers would come around the would rub on their legs before jumping onto their laps before receiving the attention he 'deserved'. He was the dominant cat. He would hiss and chase Tony, his little brother, into a crevice if he wasn't already there. He also had to sit higher than Tony. If Tony was sleeping under mom's desk, he was sleeping on her empty chair. If Tony was on mom's lap, he had to be cuddled on mom's shoulder. The only exception was probably in my room. I didn't let them on my bed because they were indoor/outdoor cats, so they had to stay on the floor. Because of this, Drew rarely came to my room. So, Tony usually hid out in my room, especially my closet.