DS, now 21, wasn't diagnosed until he was about 17 but we knew something was going on. He seemed a couple of years behind in maturity, understanding, etc. And very literal.
With a diagnosis, knowing what he was dealing with, we started watching movies together and asked questions during.... why did he do that? What do you think she was thinking? Using movies to help read faces, emotions, motives really helped. If you did a classic movie and then a lit. guide, that may help him "see" what is going on.
He did better with a literature guide, like Progeny Press.
Writing assignments on the computer sparked him, too.
Give him time. He'll get there.
Anne