According to Dr. Jennie Willis:
Cats are widely considered by owners to be a solitary species, but this is not so, despite aggression being a common problem in household cats. Observing cats in wild or feral situations in research studies has outlined normal behavior for male and female cats, which is quite a bit different than dogs but highly social and cooperative. In non-home situations, cats tend to choose to live in groups called colonies composed of both male and female individuals. Relationships between cats are highly individual and do not constitute a pecking order of simplified behaviors in response to others. When seeking to improve relationships in the cats in your household, a sense of what resources and resting places are important and valuable to each cat is important in promoting healthy relationships. Each cat relates to each other in unique ways.
What’s important here is that while many of us cat owners enjoy spending time with our cats as amazing pets, they are also creatures that think and behave in distinctive ways. And with that realization we can come to further understand our cats and how they interact with us. You’d be surprised at the observations found in cats when being in a group setting as opposed to being alone. They are much less aggressive towards one another. Granted they can be aggressive towards a new cat in the group but you’ll start to see behavior in your own felines that will only help your relationship to your own cat.
You can read the entire article at The Coloradoan