Hi! (I'm not a native English speaker and sometimes my explanations may seem weird or confusing. Don't hesitate to ask for a better explanation.) I have two female indoor cats, 4 years and 10 months old Eva (sterilised, she has been with me since she was 2 months old. She spent the her first three years with a hyperactive dog) and 4 months old Iris (soon-to-be sterilised). I brought Iris home two months ago. I used the safe room technique, but somehow I think that I screwed things up (Eva ended up hissing constantly at poor Iris, and I don't have experience with cats besides Eva and Iris) so I started again after Iris was at my cousin's for a few days. Safe room, closed for two weeks... Eva hissed twice at the door. Besides that, she seemed relaxed and happy, eating as usual (she barely lost her appetite). She hasn't sprayed or become destructive or aggresive at me at all. Almost three weeks ago, I opened the safe room door again. Iris was getting really upset inside it, anxious to be with me and Eva (she really likes Eva; she has never hissed at her. She just wants to play). There was some hissing from Eva. Iris wanted to play but Eva beat her up with her paws... Two weeks ago, they had their first play fighting session. They do that on a daily basis now. However, Iris is full, full or energy and she keeps trying to play with Eva when Eva is tired, so Eva gets angry and hisses and beats Iris up. Iris has been learning to be more gentle though. It's kind of funny, because Iris runs to Eva to jump over her but she ends up turning back 1 centimetre before touching her... she has been learning things. The most scary part is when Eva growls at Iris. I don't mind the hissing, Eva is teaching Iris how to cat, but the growls are very, very scary. Since we have had cold days (I'm from the southern hemisphere), I can't leave Iris alone in the safe room at night. I wouldn't be able to until Wednesday... and since Eva is uncomfortable trying to sleep near Iris, I had to open my bedroom's door, at least Eva will have more space. She's in the kitchen right now. Eva growls when she is trying to rest and Iris goes near her (50 cm). Iris isn't even trying to play... I'd love to sleep with Eva and Iris together, but that seems impossible... sometimes I want to give up, but I can't. Putting Iris up for adoption would break my heart, she is such a sweet girl and she deserves to be well cared for. I couldn't trust anybody else. Any help would be appreciated. I want Eva to stop growling at Iris, or at least, know if that's normal, if I'm doing things right, if there is any hope. Edit: some hours ago, Eva licked Iris and then hissed and ran away... I don't know what to think about that, I really don't... I've been thinking about using Feliway, but it may not work and Feliway isn't cheap, especially the Friends variety.