Cats can sometimes be very aggressive towards their owners, cats, and most especially other creatures both smaller and larger than them.
On observing cats since childhood, I have seen the way they deal with cats that intrude upon the territory of their group.
They oftentimes gang up on that one hapless intruder in groups of three or two after a very long stare down.
It is not uncommon to see dead cat carcasses lying around your yard in the morning due to wounds dealt by claws and fangs and sometimes stray cats carry with them bacteria and viruses which are deadly to their cleaner house dwelling brothers.
Cats are very opportunistic fighters as seen when they engage combat with dogs and other larger animals.
They run when the dog attacks first but when they make the first move they usually claw at dogs on the nose and sometimes even chase them away.
Another baffling aggressive characteristic of household cats is that when they scratch or bite their own owners.
This should not be misinterpreted as something hostile because it has been found out by several biologists that when doing these, cats are actually playing with you and should not be punished.
Cats also seem to have the ability to judge the intention of a human approaching it.
However, if it had a history of being treated badly by humans, it would have a general mistrust and if touched, would certainly execute their signature hiss signifying disapproval and a show of force.