Your cat will probably react better since he is still quite young. When my husband and I got married, we brought together my cat, who was 7 and his cat, who was under 2. They have never completely gotten along. They tolerate each other, but my cat (Tammy Faye), who is a definite Type A cat, has always hissed and knocked his cat around. Finally, Sheba (his) started to fight back. A couple of weeks ago, we got a new kitten, Ming Lee. My husband thought Sheba would mother her and I was worried that Tammy would beat her up. We had totally different results. Tammy seems bored with her and only hisses once in a while. Ming tried to play with her first. Sheba, who runs and hides when strangers come to the house, did the same with Ming. After a couple of days, she started coming out, but hissed (she had never done that in her 10 years) and tries to knock her down. I surmised that Sheba is upset more because she has been the "baby" of the family for 10 years. Also, even though Sheba was Glenn's cat, she has become my baby, while Tammy prefers Glenn. I have made a bigger effort to pick up and cuddle Sheba since Ming has joined the household. Ming continues to try to play with both of them and the ice seems to be melting. Since Tammy is 16 and Sheba is 10, it may never be a marriage made in heaven, but at least they don't do any major damage to her.