I recently bought 2 new kittens at the Humane Society. they are both about 9-10 weeks old. The male is a little smaller, but very energetic and came from a household, the other is a female who is a bit bigger than the male and a tad more shy and skittish but still very playful, she was a stray. For the first couple days the female stayed away from the male, but now they play together a lot. I was wondering how to tell if they are being aggressive towards each other or are getting along. When they play its not all batting and chasing, they will bite and kick, mostly its the male doing it to the female but he doesnt always start it. Sometimes there is hisses and spats, but not usually. I dont have a problem with them playing like this, but i dont want it to become painful to either of them and for them to stop playing together because of it. Basically I would like to know if what they are doing is normal, and will they set their own boundaries while playing? when they arent playing they do get along fine, usually taking naps near each other or both crawling in my lap together. Thanks for any responses