Richard is one of the more interesting characters on the show to me. We obviously know very little about him but he's so dynamic. Like, he seemed to be the leader of the "hostiles" but was very intrigued by Ben and somehow became under him in rank. In addition to that, he's obviously willing to do a lot for Ben (killing Juliet's husband) but has no qualms disagreeing with him either (giving Locke the file).
He definitely has a lot to offer, I can't wait to see more from him. Where did the hostiles come from? What's with the lack of aging? So many questions that a Richard flashback could answer.