Chicken is one of our landlord's cats. She's been living at their other place for the past couple of years, so Kouros has been the only cat at this residence. Now, Stan is back with 3 cats and Kouros had an encounter with Chicken at the screen door. I think it was the first time he's been close to another cat since we got him 2 1/2 years ago. He got himself all revved up to a yowl and then hissed! We've never heard him hiss before.
The funny thing is, Chicken is 20 years old. She's the Grand Dame of cats, moving slowly and not being phased by much. Kouros stopped hissing and yowling... he still had to prove himself with a couple of loud meows, at which she didn't even blink. After a while she left the screen door and settled herself down in the corner on the porch, and Kouros stood guard.