I have 3 kittens, 2 females and 1 male. They are all 3 months old and from the same litter. The male was sick for 2 weeks and was not allowed to be near the females. Today the vet gave me the go ahead to put them all together again. I was expecting a happy reunion, but that's not what happened! 1 of the females is getting along fine with the male but the other one can't stand to be around him. She hisses and growls at her brother and runs away or hides when he is near her. She is also hissing and growling at her sister which I just don't understand.
I assumed that since they are litter mates they would all be so happy to be together again! Could this have anything to do with a new pecking order? Is it a gender thing? Maybe it will be better once they are spayed? I would really appreciate any input on this, I don't know what to do. Thanks!

I'm guessing that since they are so young 2 weeks apart is like a lifetime for them so maybe this new cat coming into their lives is seen as a threat.

Try keeping the male near them but out of sight and handle one then the other.. back and forth for a day or two then let the others see but not touch the male then after a day or two give them little bits of food near each other slowly bringing them closer to each other through placement of the food.

Food is a great comforter for domesticated animals.. they need to know their food source is not under threat, feeding bits to all of them at the same time can help to reassure them.

This method worked when we introduced our new 12 week old kitten to our 4 month old kitten.. their was heaps of hissing, growling and carrying on but they got the hang of it, now they are quite civil to one another.

Good luck.

Steve

Hi
I recently bought a Black cat for my girlfriend in September he is now 12 weeks old and we recently decided to get him a playmate so we bought a 8 week old black and white female.
Its strange because while she pounces on him playfully he treats it as a proper attack and starts to claw her and bite the scruff of her neck.
He also attacks her without provocation and it's a constant babysitting job trying to separate them.
I've tried aversion with him by spraying him with water whenever he attacks her and have been for three days but it just doesn't seem to be working.
Can anyone offer any help?