So in the last episode of The Flash, Versus Zoom, we finally got Zoom's origin story. It was deeply disturbing, but yet the perfect explanation of why Zoom is so crazy. Perhaps most importantly, his origin story confirms that this is Earth-2 Zoom that we are dealing with right now. So he is not the Zoom we are familiar with in the comics - the one who is Wally West's archenemy and who manipulates times around him. It is also worth noting that the events that turned Earth-1 Hunter Zolomon into Zoom stemmed from an accident he had with Grodd, which is something they could potentially start to develop later on in the series given the introduction of Gorilla City (I really hope they show this before the season finale).
Aside from learning that this is Earth-2 Zoom, we also learned the details of how he played Team Flash throughout this season. It turns out he pretended "Jay Garrick" the entire time. The man he killed in episode 14 was actually a Zoom's time remnant who willingly allowed himself to be killed by Zoom. Personally, I wish they went with my theory that Earth-2 Zoom had a twin because that would have made a little more sense. It is also very unclear why he has a time remnant, but perhaps they will explain this later. It seemed to me that part of the reason Eobard Thane had a time remnant was because Flash and Firestorm stopped the time paradox short by closing the blackhole. So this is confusing. Perhaps Zolomon did something that caused a time paradox at the same time that the paradox on Earth-1 occurred. This might explain why the paradox connected the two earths.
Zoom explained that he pretended to be Jay Garrick because "it was fun" to pretend to be a hero and he loved playing the game. He needed Barry's speed in order to survive and felt this was the only way he could get it. But despite enjoying the game, he ran into an unexpected obstacle - love. He loved Caitlin, which is the only reason why Team Flash is still alive and why Earth-2 Killer Frost is likely still alive as well.
Another revealing aspect of this episode was James Zolomon, Zoom's father, who was a very disturbed war veteran. He shot his own wife, Hunter's mother right in front of him. Additionally, he appeared to be wearing the Jay Garrick hat and an outfit similar to the Jay Garrick outfit that Zoom used.
It seems very likely that James Zolomon could actually be the real Jay Garrick, who is probably the man in the iron mask in Zoom's lair. This would make sense, because it would explain why Zoom would keep prisoner. The iron mask would be used to prevent Hunter from having to see his face or listen to him talk. It would also explain where Zoom got the idea of pretending to be a hero using the name Jay Garrick. Perhaps Jay (which in the comics is short for Jason) is short for James. This would all make sense because Jay Garrick was a war veteran and the man in the iron mask communicated through a POW tap code. It would make the most sense for the man in the iron mask to be the real Jay Garrick because of his name having been used so much throughout this season.
The one obvious problem with this is how evil they made James Zolomon out to be. Jay Garrick is supposed to be a hero, not a murderer who beat on and killed his own wife. Look at what Greg Berlanti said about Jay Garrick.
It is possible that the memory we saw in Versus Zoom was inaccurate. Maybe Hunter Zolomon was the one who killed his mother and blamed it on his father. That's unlikely. Another possibility is that Zoom traveled back in time and changed things, making his father a good man and leaving a time remnant in the process. This explanation is tricky, but based on the hints they threw us with the costume that James Zolomon wore, there has to be something there.
Another possibility, though much less likely, is that James Zolomon's father is the real Jay Garrick. He had fought in a war and his son James followed in his footsteps. The uniform he wore was inspired by his father Jason. Unfortunately, Jay Garrick went missing and his son James grew up in an unstable home and later murdered his wife in front of Hunter. Out of anger, Zoom traveled back in time and killed his father. Then, blaming his grandfather for abandoning his father, he traveled further back in time and kidnapped him, bringing him back to the future. This would allow for Jay Garrick to be a flawless hero, unlike Zoom's father. It would also allow them to bring in an older, different actor.
It is hard to say, but my guess is that James Zolomon is the real Jay Garrick and that the memory is either off or Hunter Zolomon traveled back in time and tampered with it.
Now that we have gotten this part of the theory out of the way, I think that a somewhat familiar event is about to take place - another particle accelerator explosion. There are two reasons why I think this will happen at some point in the future.
First, there are all these characters hanging around that have super powers in the comics. Jessie Quick, Wally West, Jay Garrick (man in the iron mask) and Earth-1 Hunter Zolomon. The Velocity 9 is a fatal method of getting speed and it is only sustainable for those who already have the speed force in them, so it's doubtful that would be the way these other characters get their speed. The only viable way in which these characters could get their speed is through another particle accelerator explosion.
Second, Zoom's endgame has already taken place. He has already gotten Barry's speed and aside from Caitlin, that's all he wanted. Near the end of every season of the Flash and Arrow, thus far, something big happens. So while Zoom accomplished his goal, it is possible that the particle accelerator will come into play in the future. It is pretty clear that Team Flash is determined not to let him get away with stealing Barry's speed, so the battle is not over yet. But now that Zoom is cured, maybe he wants to unleash more metahumans and create chaos. Or maybe because Zoom's speed has likely gotten faster, Team Flash will attempt to use the particle accelerator to make Barry more powerful.
Either way it will interesting to see what happens.