On the left: the stray cat that lives downstairs
On the right: someone's pet cat that was roaming around (he had a collar, and I think he's one of the children of the stray we called Radar, but that's another story. Radar's not been seen since 2002)
They may look relaxed in the photo, but what happened was that these two met, hissed, snapped at each other, and finally settled down on the corridor in an impasse, neither giving way to each other. There was real tension in the air, but cats do this very well, lying down in deceptively sphinx-like calm while they keep a wary eye on the other one.