My calico cat, Pepper, for some reason is scared of going outside and in the garage. And…

Oh, the poor calico girl. I can’t know for sure why she’s scared. But I suspect she’s leery of the pet door because she can’t tell if another cat (or other animal) might be waiting on the other side when she pushes through the opening. She may have been attacked or frightened. She’s acting in a perfectly normal cat fashion by being cautious. Anytime a cat’s surroundings are changed, you run the risk of creating a frightening space that the cat then must learn to accept all over again.

I’m sure your parents want the cats to behave in a way that’s most convenient for them. But sometimes we must put ourselves in the other creatures’ position to understand what’s happening. Just because one or more of the other cats accept the pet door doesn’t mean ALL cats would accept the door--and it can take quite some time for many cats to accept change. You can try helping this kitty to accept the door by rubbing catnip on the opening to encourage her to head-bump the flap, and so push through. Very tasty treats (something smelly like tuna or smoked turkey sandwich meat) can be used to reward her. And be sure that with these cats, they have several litter boxes so they don’t have to share. Some cats guard the toilet and keep others away with glares and stares (we humans might not even notice). Good luck!