In the four-way crossover Crisis on Earth-X, Barry Allen met a young woman shortly before his wedding who was awestruck to meet him and reminded him to stay focused. Since then, the young woman, played by Jessica Parker Kennedy, has appeared in several episodes of The Flash, albeit extremely briefly. While many fans have speculated that she’s related to Barry and Iris, executive producer Todd Helbing says that fans haven’t yet figured out who she is.
“Some of them get pretty close, some of them they hit like one part of it but they don't get other parts,” Helbing said in an interview with TVGuide, “so it's fun to read. I don't think anybody ever is going to guess exactly what it is." Thus far, the running theory is that she’s Barry and Iris’ future daughter Dawn, or granddaughter Jenni Ognats. The latter theory is helped by a scene showing her writing in the strange language that Barry was writing when he returned from the Speed Force in the Season 4 premiere.
Another theory that has been swirling around recently is that she may be the new Earth-3 speedster that Jay Garrick mentioned. In last week’s episode, the older Flash said that he would retire once he was done training an unnamed female speedster who recently got her powers on his earth.
Airing Tuesdays at 8 p.m. ET/PT on The CW, The Flash stars Grant Gustin as Barry Allen, Carlos Valdes as Cisco Ramon, Danielle Panabaker as Caitlin Snow, Candice Patton as Iris West and Jesse L. Martin as Joe West.