Synergy, I believe it's called.

"Yes, the profile has been a little higher than of late but I shudder when I hear the word 'come back'. I don't like to think that I'm back. I've always been here. It implies something about revisiting the past. There's nothing in the past I'd go back for. No reason ever to. As far as I'm aware only Doctor Who can go back in time. "

Doctor Who's back as well, you know.

"Well, of course he's back. He can never go forward, can he?"