So I have a 1 year old cat, he’s a very leave-me-alone kind of cat and only gives affection every now and then. In July we adopted a female kitten and unfortunately she was sick when we adopted her, so we had her quarantined for almost a month. We finally made the introduction with our older cat and the first few days he did fine, no hissing just some swatting, but he would ALWAYS chase her. So we would just put her back in our room. 

Lately, he starts chasing her and trying to hurt her she has screamed/cried twice. So we just keep her in our room with some baby gates and my other cats just stays out here because I don’t want her getting hurt. I don’t know how to stop this situation; I have thought about just taking her back, but her story is just so sad and she got very attached to me and I really don’t want to. She is the sweetest little cat, but it’s also frustrating to just have her in the room and just seeing how my older cat just doesn’t leave her alone. Please, if anyone has any tips, I would appreciate them.