When I brought 5 week old calico Puddy home, she was all of one lb. and full of piss and vinegar. After keeping her isolated for the appropriate period of time, I decided that my older gal, Pigeon, a big Maine coon who was only 2 1/2 years old at that time, would be the one to introduce first. From the getgo, Pidge took charge. When Puddy rambunctiously ran up to her, Pidge put her gigantic paw on Puddy's tiny head and held it to the floor until Puddy calmed down. It was hilarious to watch as Puddy squirmed and Pidge sat there as calm as can be. Yes, you may have a few hiss and growl sessions but that's their way of getting to know one another and of establishing the pecking order. I wouldn't worry about a thing; just introduce them slowly and all should be fine. Keep us updated and w/pix, too, please.