Warning: SPOILERS for The Flash season 4, episode 11
First comes love, then comes marriage, then comes Barry and Iris with a baby carriage. That is the future most fans expect for Barry and Iris, after all, and The Flash season 4 may already be teasing this future bundle of joy. In tonight's episode, a mysterious young woman, played by Jessica Parker Kennedy, makes her second appearance this season, adding fuel to a popular theory that she is actually Barry and Iris' daughter (or granddaughter) from the future.
In the final minutes of tonight's episode, 'The Elongated Man Rises', Cisco and Ralph are grabbing coffee at CC Jitters and arguing over who will pay when a mysterious girl - the same mysterious girl from Barry and Iris' wedding during the 'Crisis on Earth-X' crossover - approaches and slaps a twenty on the counter, saying: "No worries, always pay it forward, that's my motto." She then excitedly rambles at them about helping strangers and chance meetings before wishing them a good day and leaving them be. (Cisco also compliments her Oregon Trail t-shirt, to which she responds, "Thanks, it's a classic.") Once she returns to her seat and continues writing in her journal, the camera moves in closer to reveal that she's writing in the same strange alphabet Barry wrote in when he first returned from the Speed Force.
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In her first appearance, this strange young woman was a caterer who was a little too eager to be working the West-Allen wedding, expressing that excitement to a befuddled Barry in an awkward but memorable exchange. It was that scene that first clued fans in to the possibility she could be Barry and Iris' daughter from the future, and this latest appearance only seems to cement her as a figure of some importance in the story at large.
In the comics, Barry and Iris do have children - twins, in fact, Dawn and Don Allen. Both inherit their father's super-speed and become heroes known as the Tornado Twins. Dawn later has a daughter of her own, Jenni, who also takes up a life as the speedster hero, XS. Were this mysterious young woman to be a future offspring of Barry and Iris', then both Dawn and Jenni are good candidates. Then again, the Arrowverse is by no means beholden to established Flash comics continuity and they may simply create a whole new West-Allen child (or grandchild) for Kennedy's mystery character to be.
But what of that strange writing? Well, it certainly matches the weird hieroglyphs Barry was writing in when he returned from the Speed Force, which could imply that they are some kind of Speed Force code or perhaps, more simply, a future alphabet. We already know that being trapped in the Speed Force gave Barry visions of the future, surely he could pick up a future alphabet as well? If these squiggles are indeed some alphabet from the future, then it's all the more likely that this mystery girl - whether she's related to Barry and Iris or not - comes from that future.
So then why would she travel back in time to crash Barry and Iris' wedding and hang out at their favorite coffee shop? This behavior certainly suggests she has an invested interest in Barry and Iris, and this season has already hinted at children being in the West-Allens' future. In fact, Iris could already be pregnant, a suggestion that might explain how she was able to interact with Barry at super-speed in the courtroom - she's carrying a little bit of the Speed Force within her in the form of her's and Barry's unborn child. In next week's episode, Cecile will develop temporary meta-powers as a side effect of her pregnancy, so it's not out of the question to think the same could happen to Iris.
The Flash season 4 continues next Tuesday with 'Honey, I Shrunk Team Flash' at 8pm/9c on The CW.