Ever had a hopelessly DULL friend?

You need a lot of patience in understanding his mind set, after all he's your friend. I think it should be better if you talk to him with someone, because it would be easier to talk to him if you have another to talk to, like talking as a group. Show more interest in listening to what he has to say. When you are talking as a group maybe it would be better if you two know the other person you are talking to at least you two can still be open even if your conversation is not just between the two of you plus you will not look like talkative because there is someone that will talk to him also. you'll never know maybe he knows something more than intelligent stuff you just need to find out and tickle him with conversation..