These are my cat (Tuna, Black) and new cat Key Lime (brown on the other side of the door). We did the slow intro since we got key lime on 03/13/26 and things were going okay with less and less door hissing but we’ve kinda gone backwards in the last few weeks and this is how they are now. Key lime seems to be want to play but will occasionally get overzealous and run toward tuna on a few occasions which seems to stress tuna. Tuna will do this when key lime comes to the door or try to completely ignore her or just put some distance but fixate on the door. On the occasions that we try to feed the with the door ajar or through a screen door, they seem okay for a few minutes but then tuna will start growling or hissing. We have tried to distract them with pets or play but Tuna will just want to get away instead of accepting any pets or treats as a distraction and she doesn’t really like any of the toys we’ve gotten for them so far so I am out of ideas on what to do at this point. We (husband and I) have not felt comfortable letting them be together without a barrier out of fear that key lime may test boundaries too much too fast. On the times that key lime has gone into the bedroom where we keep tuna, tuna runs under the bed and key lime will run after her and try to get close or just not leave her side u til we remove her and tuna just hisses. During the days we keep tuna in our bedroom and key lime on the rest of the apartment. When I switch them it can only be for a few minutes as key lime (who is much more energetic) either tears down of the room apart or just seems bored and tuna scratches at the door to be let back in. I am not sure how to proceed here.
TLDR: this is how my cats get after almost 8 weeks of slow introduction with almost no progress now. Any advice would be appreciated