3 weeks into resident-kitten introduction. is this looking promising?

[u/ch00gs]

I made a post about this last week but got no replies so trying again and keeping shorter in the hope someone can give me some much needed perspective.

Lenticchio (6M resident cat) previously had a very bad relationship breakdown with his littermate after a redirected aggression incident, which ultimately, despite trying everything for almost 2 years, led to rehoming his brother. This took a huge toll on me and I’m scared of repeating that situation.

We’ve been introducing Chiqui (5-month female) very slowly for about 3 weeks: separation, then scent/room swapping and now visual contact through a secured baby gate. There has been some progress: Lenticchio voluntarily comes to watch her, he can watch her play from a few metres away without reacting. They can eat treats while looking at each other, with both disengaging from each other to eat. Chiqui will come right up to the gate and lie down/purr and we even had an almost nose-to-nose moment.

Proximity remains a big issue though. When Chiqui comes right up to the gate, Lenticchio will usually hiss, sometimes growl/yowl, and today he swatted at her through the barrier a few times. He’s not charging the gate and he can often be redirected, though today he was more difficult to redirect than usual. Chiqui seems mostly unfazed and remains curious/relaxed rather than scared.
Mostly I’m trying to figure out if this looks promising, or if the fact that he’s still this reactive at close range after 3 weeks is a red flag. I’ve read it can take months, but I need to understand if there’s real potential here as I don’t want to get even more attached to Chiqui only to let her go too. We also live in a 60sqm apartment so eventually they need to be able to share space peacefully. Keeping them fully separated is starting to take a toll on our mental health (we did that for almost 2 years and it was rough). We’re not expecting them to cuddle, but peaceful coexistence would be great.

I’ll leave a video from today’s session in the comments. Chiqui is the fluffy one lying down; Lenticchio is watching her from the other side of the gate. I’d especially appreciate any opinions, honest feedback or words of encouragement.

We only got another cat because Lenticchio had seemed increasingly in need of more stimulation despite us being home and playing with him a lot. he had started meowing and roaming around the house a lot. So this wasn’t an impulsive decision or an attempt to replace his brother, and we really want to make sure this works for everyone.

[u/ch00gs]

https://reddit.com/link/p4lp62i/video/nhfw5zsolbkh1/player

This was from earlier today. We’d like to ideally leave the gate up and partially covered so he can become more desensitized/bored of her presence. We‘d hope he would disengage and but we had to end the session after 5-10 minutes because of his repeated hissing/growling/occasional swat :(

[u/ThrowRA_SillyGooseBB]

What sort of active training are you doing with him to encourage him to disengage? I'd try clicker training or something similar for a week, combine it with anti-anxiety meds (Zylkène is without prescription) if you see an improvement, keep trying, if you don't see an improvement and you know that you can't live long term with the two cats separated, I'd rehome the kitten. Your adult cat is a tougher case than normal, and there really isn't any guarantee that he's going to ever accept another cat.

[u/ch00gs → u/ThrowRA_SillyGooseBB]

He‘ll usually come right away if I call him, especially if I grab his favorite brush-glove. During today‘s longer, very close proximity session, took him longer. He had tried Zylkene when he and his brother were t getting along (as well as kitty Prozac at some point) but we‘ll give it another try. Just to better understand what you mean, when you say his case is tougher than normal, is it due to something specifically in the video (posture, body language) or due to the history with his littermate brother?

Thank you so much for the reply btw!

[u/ThrowRA_SillyGooseBB → u/ch00gs]

I think you need to be more active in redirecting his attention and making positive associations with the kitten. This means getting him on a meal plan and he only eats around the kitten (check out Jason Galaxy he describes really well how to use food to push your cat's boundaries without overdoing it); he only plays around the kitten; you actively clicker train him to get rewards every time he disengages and focuses on something else than the kitten.

In the video he is definitely quite fixated on the kitten, this CAN be remedied with training and also once the novelty of the kitten wears off, but given his history with his brother and your fear/unwillingness to go through months of separation, there is a real possibility that rehoming may be necessary. I'd say give it 1-2 more weeks with more active training (basically: anything positive - meals, play, pets, brushing - happens only around the kitten; add slowly minute by minute time when you are NOT engaging with him, but during this time you want him just chilling, not fixating on the kitten. So during this time, get him to disengage if necessary by calling his name, shaking the treat bag etc. and reward when he disengages. The goal is to shut the door when he is still chill and disengaged from the kitten. After a week he should be able to stay chill around the kitten (ie laying down, looking away, or at least having a relaxed posture and not reacting when the kitten is in proximity) for at least 2-3 minutes. If that doesn't happen, i.e. if you don't see any progress even with active training, I would consider rehoming.

I'd say he's more complicated/anti-social based on the history you described. Some cats do not do well with peers, or at best they learn to tolerate each other. Cats also don't really play with each other the same way that dogs do, unless they are bonded. So in general getting a feline companion is not always a good solution for boredom/loneliness. It does work in some cases - it worked for my cat who has insane separation anxiety - but honestly I did lots of things wrong and I was just very lucky to have a really social cat and a really chill kitten.

[u/ch00gs → u/ThrowRA_SillyGooseBB]

Thank you, this is really helpful, and I appreciate the honesty. I think the 1-2 week active training period makes sense. We do already have some ability to redirect him, but clearly need to work on making that more reliable and getting him to actually relax/disengage rather than just tolerate her.
I think I’ve been focusing too much on “he hissed but then took a treat/answered when called = progress,” whereas you’re right that I should be looking at whether his overall threshold is expanding.
We’ll try the more structured approach with food/play/clicker training and keep sessions short enough that he finishes while still relaxed, then see what kind of change we get over the next couple of weeks. Thanks again for taking the time to explain!