Once he moved over here full time, the dynamics of having 7 other cats made him a bit... more cautious. Not really nervous - I think cautious, or wary, are good words.
It took Billy 3 months to really get his purr going, and we knew it would take longer for Chum to really settle in, especially when in September Shelly decided he had an issue with Chum using all his spots.
With the help of a wonderful animal communicator, we got that situation resolved.
Chum often spends part of the night in the bedroom, and he's clearly totally comfortable around us and has been all along... but unless he was sleeping, he didn't enjoy being brushed or petted (he enjoyed it if waking up into it
And for the past few mornings, when I head out to clean litter boxes (first thing I do in the am LOL), he's been coming to greet me, crooning, and he walks the back of the couch - and puts his head down, saying, "bump me, mom!" (I started "petting" Bill and Chum with my head because they're so cat friendly and at first were scared of hands reaching out at them). And while that's pretty normal - for the past couple of days, each morning he starts purring his big old rumble purr when I pet him with my head!
And today he independently came over to walk back and forth across my lap as I'm using the laptop on the couch, and he enjoyed a good brush... and he let that rumble loose!