Cats are solitary creatures. This means they do things alone. Cats, excluding lions, prefer to travel and live alone. But, usually, a mother cat will stay with her cubs long enough for them to grow and establish hunting skills.
Cats fight because they are fighting for a mate, territory, or both! Take the lion for instance. A bachelor (soilatary lion without a pride or group of lionesses and their cubs) lion will invade another pride and kill or drive out the leader cats. They will kill younger cubs to free up the lionesses for mating or allowing them to hunt again.
Cats will sometimes come together for mating season or a large hunting party.
God made cats like this to help them survive.
I hope this helped! It was kinda factual, but that's what you wanted, right?