Given how much they have gone out of their way to disguise any features and even the voice Zoom has to be someone we know. I thought the preview showed Earth-2 Barry and he was like full nerd or something? Anyone they show next week I don't think will have much chance in being Zoom. I have a feeling Zoom is too busy doing evil Zoom things to even want to live a normal life where Barry will be able to see him and not know it. I do really like the Barry's dad theory, I didn't even think of him as Zoom. For now I would have to hold that it has to be someone Barry has an emotional connection to on Earth 1, it has to be hard for Barry to fight Zoom. That emotional outburst of "You're not _____!!" could be enough to push Barry to go fast enough to beat Zoom.
XI Wiki



