I've had my cats for years. All of them are sweet. They go outside and walk along me when I do yard work and take care of the animals. And they are snuggly inside, sometimes jumping into my arms or onto my shoulder (...like a Pikachu.) Today, my oldest tomcat was in my lap, purring and enjoying some attention- then, without any notable warning, he jumped up, curled around the back of my neck, claws digging into one of my shoulders... and he BIT the back of my neck. It wasn't hard, it didn't draw blood, but I definitely felt teeth. I immediately pulled him off and put him down, and he's been laying around like a lazy cat ever since. Why did my cat randomly bite me?