You called him a 'smoke black shorthair' - is that the actual breed name given by the sellers, or just what you're calling it - I ask because if in fact he's a medium-darkish purpley gray, with greenish eyes, he could be a Russian Blue (or mostly) of which I have one and which are known to be very skittish - takes quite a while them to trust anyone. Mine only allowed me to touch him x 10 yrs, and now at 14 will just barely let my husband pet him a couple of times in a row! Jumps at every quick or unexpected movement, etc. etc. The best thing is to just ignore him as much as possible til he starts to feel at home. Be there, talk a lot, but try to avoid sudden noises and especially movement. Only ever present the back of your hand (no wiggly fingers) to him - it's less threatening, and don't try to pet him at all til he loosens up a lot - but the method will allow you to get closer faster. DO play with him, throw little (1+") balls for him to chase, knot a 4-5' cord at both ends and drag/jiggle under a sheet of newspaper, get a Da Bird toy (stick with feathers on the end) or a laser pointer so he can chase the light around the room. Make sure he doesn't dislike his litter and give him variety at meals. Let him make the approaches and don't let children or strangers try to grab him, etc. .