Generally cats will avoid conflict as this presents a threat to their survival but there are a number of reasons why there might be aggression between cats.  Most cats will attempt to defend their home range or the area they consider most significant to them.  Assertive cats in the neighbourhood may deliberately seek out opportunities to extend their territory and may target less confident cats as they represent an easy target.

A cat who is unable to or is unsuccessful in defending their home range may become housebound as they feel it has become too dangerous for them to venture outside.  Cat flaps or even a window Cat fightpresents an opportunity for a strange cat to invade the home and this can lead to aggressive behaviour from both parties.  A resident cat may even surprisingly not seem to respond to or seem to oppose to an invader from a human’s perspective but this is more likely to be due to fear rather than an act of acceptance of the encounter.

This territorial behaviour may also be apparent in multi-cat households.  As the home becomes subdivided by the more confident cats, a less confident cat may be reluctant to venture out of one room, except at very specific times, due to fear and to avoid conflict and the risk of harm.

Aggression is usually a consequence to an emotional state rather than to a cat’s temperament but certainly some cats may be more likely to be aggressive under challenging circumstances than others.