when he slow blinks it means mario trusts you, and is comfortable with you. it's a good sign your mario won't try to bolt out the door whenever it opens, but it's still good to be careful, because even if he feels safe with you he is easily startled and can't think very far ahead https://twitter.com/MarioBrothBlog/status/1312836253067497478

sometimes it just means your mario is sleepy. try to not over anthropomorphize the mario by reading too much into his actions as indicative of a human-like experience he may not have. it's also why what we see as mario playing he might experience as serious, even violent activity

also no matter how your mario behaves around you and others he's familiar with, please be courteous about keeping him on a leash whenever you're out and about. some people are allergic to marios, have a significant fear of mario jump attacks, or he may disappear into a sewer pipe

P.S. in case people continue RTing this thread, my current soundcloud is I just started a free weekly email series sharing #gamedev tips learned from years of training people new to game development - which you should probably join or RT to share, k thx https://twitter.com/HomeTeamGameDev/status/1312503866684964864