The first day, Angelica and our older cat (Beeman) did NOT like one another, but I expected that. There was no scratching or biting, just a lot of hissing and growling. It only took a few days and although they are not best friends yet, all of that hissing and growling has pretty much stopped. She was very timid for the first 2 days also, but now she is so full of energy - definitely a change of pace and she keeps Beeman on his toes. We've also learned that she likes sandwiches, so now when I make the lunches in the morning I have to put them in the fridge right away!