Hi! About 1 month ago we added another cat to our family, we already had a feral cat who I found 2 years ago that was just 5 weeks old who has bonded to us well and is very needy for affection by following me everywhere, etc... The feral cat is a male, dark black with yellow eyes. The new cat is a 3 year old female gray tabby who is very loving. Ollie the male cat is very small for a cat he weighs just 8-9 pounds, compared to Abbie the female cat who weighs in at around 15 pounds. We kept them apart from each other for several days, we showered Ollie with lots of attention, then we slowly introduced him to Abbie for maybe 10 minutes completely supervised by us. After 4 weeks of playing musical cats by moving them to different parts and rooms of the house now we have left them interact. Abbie surprised us when she swatted Ollie 3 times last night and hissed at him. Ollie does not want to leave her alone and wants to sniff her and pounce on her if given the chance. What should be do now?? Ollie is alot more aggressive then Abbie and he is much smaller in size. We shower them both with lots of love and attention. They seem to be alright in the same room if we play with them or give them treats but otherwise Ollie stalks Abbie. Any suggestions you have are most appreciated!
Firstly i am assuming they are both neutered as this will reduce aggression and calm the situation down.
It sounds as if you have done everything right apart from that, you have taken things slowly and given the cats time to get used to each others smell etc.
Unfortunately it will always be in a cats nature to defend territory and as you say establish a hierarchy. The behavior that your cats are displaying is normal in this period of socialization and to be honest there isn't much you can do apart from let them sort it out themselves. Usually after a while they will settle down once they have worked out their positions in the home and with each other.
Most cat fights sound a lot worse than they are and a lot of it will be just warning shots and growls etc. To be honest the best thing you can do for them is let them get on with things and only intervene if things get out of hand. This is natural cat behavior which will sort itself out.