Hera the Cat is a very special member of our family. Though she didn't come to live with us until after we moved to Colorado, Hera and I have known each other for over 20 years, longer than anyone else living in this house. She was my sister's cat when I was a kid; we go way back.
With her age comes some well-earned attitude toward anything and anyone who threatens her right to live out her remaining days/years in peace, especially obnoxious dogs who bark too loudly in her presence or mistakenly think they can intimidate her. She has an impressive resume of dog-training experience, including special kitty karate moves that she has perfected over the years and the ability to chase a dog around the house in true horror film fashion until they bow to her superiority. Hera may be old and feeble, but there's no question that she's in charge.
So when we brought Calvin home, we were more than a little nervous about her response to him. For the first many months we kept the two apart. Now, though, we have relaxed a little, allowing contact between Hera and Calvin only when Hera approaches him, and only when we are there to closely monitor every second. Calvin of course is thoroughly delighted by Hera's presence, and Hera will occasionally respond with a nice purr. She's been remarkably patient with him, not even flinching when her fur, skin, ears wind up in a tightly-clenched fist and fist-fulls of her fur get pulled out. Of course her patience has limits, and we don't wait around to see what those are. It's clear, though, that she has learned to appreciate Calvin's presence in our home in one immensely important (to her) way: with a baby comes many fantastic napping spots.