In a recent interview, Joshua Jackson talked about the return of David Robert Jones to Fringe and while he said that he couldn’t elaborate, he did offer some explanation.
“I can say from a personal standpoint that the fact that we’re getting back to David Robert Jones and going back basically into Season 1 to rehash all of that stuff, is super-cool. And [Jared Harris] is a great actor to have on the show. But I don’t want to give away the way [he returns], because if you’ve been watching from the very beginning, it’s a very satisfying reveal.”