If you've watched the most recent episode of The Flash on the CW, entitled Escape from Earth-2, then you were certainly left with some questions, one of the biggest being: Why did this guy...
... tap "J-A-Y" to Barry and Jessie? And also, what does it mean? There's no doubt that it's referring to Jay Garrick, but what about him? Was he trying to warn them that he was in danger? There are so many possibilities, all of which could be evidenced through the show. So, let's look at three of the big ones.
Jay is Zoom.
This theory is a little bit far-fetched, but there is a decent amount of evidence for it. Jay lied about Zoom stealing his speed and hid the fact that Velocity-6 was why he was slowly dying. He wanted speed, so he tried to figure out a way to create more. But if Jay were Zoom, why would he come and start to work with Barry? Easy: to make him faster.
Jay taught Barry how to throw lightning and has encouraged him to get faster and faster. He warned Barry not to face Zoom because he would know it was a trap, which he did and he was able to catch and hurt Barry anyway. And how would he steal Barry's speed? By employing Earth-2's Wells to do it for him without revealing his true identity. Plus, he was having Caitlin figure out a way to restore his speed permanently. And let's not forget that his double on earth was named *eh-ehm* Hunter Solomon, who in the comics IS ZOOM.
Now this theory does have a number of holes, evidenced in the footage of Garrick fighting Zoom previously without any sort of mask, and by his visibly being on Earth-1 with Cailtin for nearly all of the episode. And that's not even counting what happened at the very end of the episode! You know, hand through the chest, pulled into the closing breach. But that leads to the next theory...
Jay is working for Zoom.
This theory is also a bit far-fetched, but entirely possible. There could be a partnership where Jay is working with Zoom, but what would his motivations be? He is dying, after all, so trying to find a way to save himself and gain back his speed would be important for him.
Teaching Barry to get faster and steal his speed would work, but Zoom would simply keep it for himself. Caitlin figuring out a way to heal him would work as well, but Zoom could also use that remedy to make himself faster and would end up killing Jay. No matter which way we went in the partnership, Jay would most likely end up dead. Zoom is all about hoarding speed.
But there is one more idea under this theory. Jay Garrick could be a clone. Yes, outlandish, even crazy. Why would Zoom clone Jay? Honestly, I don't know. Why don't you ask him? And somewhat tied to this idea is the next theory....
The man in Zoom's lair is the real Jay Garrick.
Crazy? Yes. Outlandish? Of course. Possible? Completely!!! The man tapped "JAY" for a reason, and he was extremely upset when Jessie and Barry were talking about Jay Garrick and how he was safe on Earth-1. This could mean the man was worried about Jay, but why would he be?
There are also two important pieces of information we need to look at in this scene as well. The man was wearing a mask, and clearly not of his own will. The mask impeded his ability to talk, and Zoom didn't want him communicating with the others locked in his lair. Why would his identity be so important to cover up from Barry and Jessie?
And secondly, he was placed in the same carbonite-box that Barry was locked in. Logical conclusion, he was a speedster. Yes, Killer Frost's powers had no effect on the box, but that doesn't mean other powers would work just as well. And if Barry had trouble shifting through the invisible wall, wouldn't the beaten-and-bruised Jay as well?
If the man in the mask is the real Jay Garrick, that begs the question, who is the Jay Garrick we saw the whole time on Earth-1?