We have a 5ish year old girl cat. We had two cats until last July when our other cat got super sick and we had to put him down, so she's not a stranger to having other cats around. We thought we'd get another cat so we picked out a 10 month old girl from a local shelter and adopted her and so far they are getting along 0%. We didn't introduce them face to face until 4 days in and we've kept them separated during the day but have tried to leave all of the doors open at night and they've had a big fight that we've had to break up every night. It's a week that we've had the second cat today and not only are they still hissing at each other but new cat scratched my wife when she tried to give her some attention.
Do we need to give it more time? Is cat #2 just a bad fit?