Awwwww, he's a handsome big boy! The tabby on the right is a cutie. Looks like they are interested in interacting with one another. It will just take some time. Also, I once tried to put a harness on a cat that I had rescued that used to be outside and was inside. I made the mistake of thinking maybe she would like to be outside in the back. She freaked out, and was actually able to get out of the harness. I was able to catch her and take her inside right away. Needless to say, we didn't try that again!