My kitten is attacking my new kitten!

by Justine
(Hereford)

I currently have a male kitten of 12 weeks, and have owned him for two weeks now. Yesterday, I got another kitten, a female of 7 weeks to keep him company when myself and my partner are at work, but the older cat keeps launching for her.

The male kitten (Mortimer) is very playful but I'm not sure if he's trying to play with her or if he's actually attacking her.

I've introduced them through a closed door and also through the carry cage and have the resident cat come up to her. There was initial hissing but that seems to have stopped.

Now he just has large pupils and it's almost like he's hunting her around the room like she's prey.

When they "fight" she runs off but he always seems to run after her and jump on top of her while biting and scramming. She yelps out but I'm not sure if that's because she's in pain.

They're eating their food in peace next to each other without any squabbling but as soon as they stop, he's back at attacking again.

Please help! I don't want to have to get rid of either one of them from the house but I need them to live nicely together.