1) Okay, several times throughout this blog you state that time travel is required for a doomed timeline to exist. I thought this was right, but I'm doing a re-read, and at h t t p://w w w(.)mspaintadventures(.)com/?s=6&p=004994 Terezi clearly outlines a choice-based multiverse - that is to say, every separate decision creates a different timeline. Yes, Green Dave DID travel back in time to that point, but his timeline existed before that happened.

That’s not entirely accurate. In that particular doomed timeline it was choice-based but only because the choice involved time travel. Green Dave’s timeline may have existed before he time traveled but Alpha Dave’s timeline did not. It was Green Dave’s choice to time travel that doomed his timeline. When he went back in time and died he altered the timeline so that his timeline could never happen and Alpha Dave’s would. And if the two timelines were always separate timelines then we’d be dealing with multiversal travel not time travel, one needed to branch out from another.