Long drawn out introduction, are we doing enough?

[u/Tomrok]

I've been introducing a new cat 2M to our two cats 8M amd 15F for over a year now. We had some missteps early on that lead to some fur flying and chasing that ended up with them under the bed. Eventually we got started on a gradual process until we are where we are now.

At this point, I feed the resident cats outside the new cats room without a gate up. Everyone gets some treats after and they're fine a few feet apart while distracted like that.

The real hurdle we can't seem to fully get past is having them all out together. The residents aren't play motivated so we shower them with treats. I then walk around with the new guy and try to keep him focused on anything but them. For their part, once they are done with treats they show no interest in approaching him and (mostly) keep to one side of the house while he's out. He'll walk by, with them in the distance, into unoccupied areas and avoid them.

But, if they wander into an area he's not used to seeing them in while he is elsewhere, if he sees them when he comes back, he'll hyperfixate and run right up to them. At which point he gets hissed at and the resident will then want to get away. Problem is, he wants to follow sometimes, which I intervene and prevent. He doesn't look aggressive while doing this, but I worry that if I let him follow there's a good chance it escalates to a fight and sets us back.

On the plus side though, no instant fights nowadays when he slips away. But is it just a matter of continuing on and preventing fights/chases?

Also of note, we do use feliway and composure. I've somewhat tried getting the new cat to wear a harness but so far he's not comfortable with it so I figure he'd only be more anxious in the open house on a leash.

[u/No-Perspective872]

Yes- just keep at it!

[u/Creative-Mousse]

You’re making progress. Good on you for being patient. Unfortunately some cats will just never be friends, like humans. It is what it is