Most of the time they were hunky dory and coexisted just fine. Havoc has always gotten nervous any time he smelled or saw a strange cat, like if a stray outside sprayed something that eventually came in the house (like firewood), or he saw something through the window. He would then act rather confused when he saw Toby, but smelled this other cat. He'd then get nervous and defensive. I avoided other people's cats if I knew I was going home afterward, and tried not to bring anything from outside to inside where they could smell it. This worked most of the time. If they did start fussing at each other, putting one of them in the cage for a couple hours would allow everyone to calm down and they'd be fine by the end of the day. Things started changing last summer for some reason. Havoc would get all freaked out and nervous completely out of the blue. They would both be curled up on my lap asleep and when they woke up start giving each other the stink-eye. This was happening more and more often and without any apparent reason, so "kitty jail" was getting used with increasing frequency. By April they couldn't be together for more than a few minutes. So as of now, when one of them is in the cage they're fine, even face to face. Heck they'll even play footsie through the bars. It's just if Toby walks out of the room and then comes back in, Havoc acts like he doesn't recognize him. Every time I take them to the vet everything checks out just fine. I'm wondering if Havoc's eyesight is going, or it's his mind that's on the way out. He's only about 4 years old, but he's never looked particularly healthy and he's always been rather "dense" mentally. He's the sweetest, most playful, happiest, little guy otherwise. My parents always play with him when they come over so at least he's comfortable with them.