Harness training??

I have adopted indoor cat from shelter not to long ago.
I have 3 shed cats in my yard who come to eat at our patio. Whenever my indoor cat sees them, he meows and wanting to join in and play with them. Once he took off by following one of outdoor kitties. Outdoor kitties are receptive of him. They have been sniffing him through screen door and they are meowing back to him now.

So, I decided to harness train him but he seems to terrified with outdoors. His initial harness experience was so traumatic that he runs away whenever he sees harness now.

Shall I continue to harness train him? The one we tried was "come with me kitty" harness. This one comes with bungee type harness which made his experience really bad.

I am also wondering if he came from multi cat house hold. Unfortunately, our county shelter didn't have any record of him even though he was owner surrender.

I am starting to wonder if he would be happier in multi family cat house hold than single cat house hold….

You might have something there - it's not that he wants to be outdoors, but with the other cats, so finding a friend for him (a younger male of a similar temperment - nondominant would be a good start) is a good idea. I say nondominant because so often new cats try to take over.

I agree. Now seems like the perfect time. See if you can find him a buddy!

That's what I thought.
Second cat is not an option due family reason.

Do you think re-homing him to multi cat family is better idea?
I really want him to be happy....

You might try playing more interactively with him - there are a lot of toys out there now, but even a fat cord with knots on the end dragged under a blanket will give him lots to pounce on, as will little foil balls (which will end up under furniture!), and of course a cat tree with a perch at least 12 x 14" wide, especially if the posts are sisal wrapped for scratching. One of my cats if nutso and loves me to toss paper clips at him all day so he can jump a bit (not too high) for them and hide them under the carpet.

Oh, the foil balls. Our cats love them. We can't tear a piece of foil off the roll without them running downstairs.

I hope things work out with Leo, Kazy! I have been following your situation over in the feral thread. I am sure there is a solution out there!

Thanks for your advice!

It seems like having more playtime is working out.
He needs more physical, running around type of play.
We didn't do that kind of play that much before because of his cold.
He is still sniffling, but getting better.
He is biter, though. I have to promote non biting play time.