Well hes jst shy. Or not too sure of himself if you will like him. And well look intently means hes lookin for how r you feelin while talkin to him or maybe jst checkin that you don't dodge him. So do not lose eye contact on your part. Cross his arms means hes gettin blushed inside or not knowin which position to be in. Or not sure of his body posture. If he smiles then it might be to signal you. Or maybe he wants to show hes havin a happy time . Or maybe thats st natural. Now y he doesnt say hi 1st maybe because hes shy . Try sayin hi a few times. Or maybe pass nearby him wen not a lot of ppl are around and see if he calls you
