When The Flash inspires its fans to craft endless amounts of insane theories, it usually involves a character or plot device that gets seen or referenced on a regular basis. Not so much with Jessica Parker Kennedy's as-yet-unidentified Mystery Girl, who's had us flummoxed about her importance ever since the first part of the Earth-X crossover. The good news is that we're closer than ever to finding out who she really is, and the potentially better news is that she's actually setting up something for the future. According to showrunner Todd Helbing:
Everyone will get an answer to who exactly The Mystery Girl is, and how she plays into not only this season but next season.
We already knew that The Flash was probably going to offer some answers about Mystery Girl before Season 4 was up, and Todd Helbing had also recently clarified that the character's purpose has been to drop clues and hints about how these episodes are slowly setting up Season 5's arc. And now we know that Mystery Girl isn't just setting things up for other characters' stories in the next season, but she'll actually be a part of it herself. And in a way that's hopefully more prevalent and informational than these bizarre little appearances have been.
This makes me want to rethink all of my previous theories, but then to defend them all at the same time. If Mystery Girl will indeed factor into Season 5 in a meaningful way, as Todd Helbing implied to TVLine, she's probably not a time-traveling speedster, since that would create timeline problems for the Speed Force. But then, if Mystery Girl isn't related to the Speed Force, then what was she doing writing down those weird symbols that Barry was scrawling in the season premiere? Of course, time travel could still enter into it, since the Legends of Tomorrow crew doesn't use the meta super-speed to dip into the past, but we'll leave the Waverider out of this for now.
Sticking around Central City for a while wouldn't preclude her from being from another Earth, though, since Harry is living proof that unless one has emergency responsibilities within a home dimension, they can basically do as they please in other worlds. So it's possible that Mystery Girl's connection to Barry's symbols is tied to a completely different version of Earth, which would add an interesting wrinkle. (What if the Speed Force isn't the Speed Force at all, but rather just a really weird Earth Zero?)
Obviously, Mystery Girl could very well just be a normal, present-day Earth-1 citizen, with her stranger story details coming from another facet of her life. She could be Barry's sister. She could be related to Iris. She could be a CC Jitters employee running a conspiracy theory website, and she spends her free time tracking Team Flash's baffling adventures. It probably won't be any of those, but it could be. And that's why The Flash's mysteries are so fun to think about.
We have yet to see Mystery Girl have multiple conversations with any of the characters, and we also have yet to see her mix it up with anyone outside of Team Flash. And we have yet to find out if she's a good guy or a villain. But at least we do know that The Flash won't just kick her to the curb after revealing who she is. Although I guess it could give her a different body and identity and name.
The Flash is close to wrapping up its Think-provoking fourth season, with the finale coming on Tuesday, May 22. But be sure to tune into The CW on Tuesday nights before that (at 8:00 p.m. ET) to see how well the road to the finale will be paved. And in the meantime, check out when all the other big finals are airing, and head to our summer premiere schedule to see the new and returning shows on the way.