I'm sorry for all the questions lately, but I don't know any other cat owners, and this forum has been really helpful
We have a 1.5 year old female and introduced an approximately 1 year old male a week and a half ago. They are both fixed. We kept the new guy in a spare bedroom for a while, swapped scents etc.
There were absolutely no signs of aggression at all, and it became apparent that they wanted to meet, so we let them meet last week. They touched noses and played together a little. We've been letting them have supervised visits and have been stretching the time out a little each day. All of the interactions were incredibly positive up until a few days ago.
The problem is that the last few days they have started to hiss and growl at each other and there have been squabbles where it sure doesn't seem like they are playing. It seems like the new guy is getting very territorial about his isolation room all of a sudden... and that seems to be the only place our resident female wants to go. When we first open the door they touch noses and are friendly, then it sort of goes downhill.
I am a little upset because things were going unbelievably well, and we seem to have taken a step back... but I understand that they might be trying to establish who is top cat, and squabbles like these are inevitable. But, at this point, should we just let them work it out, or should we separate them when they start hissing? Should we decrease the amount of time we let them interact?