welcome to the forum teenman! jsut fyi, i nthe future try to search the forum for ideas similar to yours, i believe your question has already been anwered somewhere else. it's not that big of a deal now, since this is your first post and all, but in the future try to be ware of that.
anyway in answer to you post, the reason DD avoided eye contact w/ harry was because he was afraid of voldy finding out that he and harry have more of a relationship than professor and student. why? i don't really know myself. also during DD's speach when he talked about the prophesy and all he mentioned that he should've taught him occlemency, so, if harry does continue w/ occlumency, i believe that it will be w/ DD.
again, welcome to the forum and check out the new memberes welcome forum! happy posting