Hi: I have a 2 year old female cat named Sabrina. Four days ago my mom and I went to the welfare and adopt a beautiful 3 and a half month old female kitten that we named Olivia. Sabrina has her own safe room, my room and the kitten sleeps with my mom. Sabrina is a very agressive cat towards anything that comes from the outside world. We live in an apartment. We slowly introduced Olivia to Sabrina and sometimes Olivia try to defend herself and hissed from now a then but i get very anxious and put Olivia in her safe room. I dont want to mantain her confined in a room forever, but i dont want them to fight either. Sabrina is very tough on us growls, hisses and we are kind of scared for the kitten.