My anecdata: the Maine Coon brothers will meet strangers at the door and stare at them. If the stranger enters, the cats will start to hiss. If they come furthe

My anecdata: the Maine Coon brothers will meet strangers at the door and stare at them. If the stranger enters, the cats will start to hiss. If they come further inside, the cats will attack. When we're expecting our HVAC folks, we lock up the Mainers in a bedroom. Meanwhile, the Siamese look inquisitively at the strangers and then run away.