We often equate feline social behavior
We often equate feline social behavior with our own or with that of our other most popular companion animal, the dog: this is misguided.
Cats live together on their own terms and for their own reasons, which are quite unlike ours.
The cat's social behavior is governed by territory and food; relationships with other cats are possible, but less important than control of property.
Almost any cat feels overwhelmingly threatened when another cat, even a kitten, appears on its territory.
From a human perspective, such behavior appears antisocial, but this is not strictly true. Cats are far less solitary and more sociable than was once thought.