The Flash EP Reacts to 'Mystery Girl' Theories — Could She Be [Spoiler]?

The Flash‘s Mystery Waitress (or, as listed in scripts, “Mystery Girl”) has served up nothing by questions since she first appeared in the wedding portion of this season’s crossover event. And she will continue to do so a short while longer.

Following a press screening of this week’s episode, “Run, Iris, Run” (airing Tuesday at 8/7c, The CW), executive producer Todd Helbing was tight-lipped about the intermittently appearing character’s identity, instead only saying that the assorted fan theories he has heard are “pretty fun.”

As with Season 1’s Reverse-Flash, Season 2’s Zoom and the Man in the Iron Mask and Season 3’s Savitar, “Every year, there are theories all over the place about what we’re doing,” he said. “Some of them get pretty close, some of them hit, like, one part of it, but they don’t get the other parts.

“I don’t think anybody ever is going to guess exactly what it is,” he added, referring to Mystery Girl’s identity.

Played by Black Sails‘ Jessica Parker Kennedy, Mystery Girl bears a resemblance to Candice Patton’s Iris, talks fast (and sometimes in techno-babble) like Barry and seemed overly excited to be on hand for the WestAllen wedding. In a second appearance (detailed below), after she “paid it forward” by treating Cisco and Ralph to coffee, we realized that she writes using the same symbols that Barry scrawled upon emerging from the Speed Force prison. Most recently, the audience learned that she was at Jitters waiting to bump into Caitlin and Harry. So for those keeping score, she has interacted with (and almost always physically touched?) everyone from Team Flash — except Iris.

Long story short, many suspect that Mystery Girl is a future, time traveling child of Barry and Iris’ — likely, speedster Dawn Allen.

Again, Helbing was mum, though he did share a curious clue about the costume Iris wears during her temporary turn as a speedster: its purple color was chosen for a reason, one that we will “find out soon.” Hmm, what is Dawn Allen known to wear….? (With reporting by Vlada Gelman)

Herewith, a summary of The Waitress’ first three appearances in Season 4:

Episode 8, offering Barry a water before his wedding to iris: “I thought you might be a little parched. Big day, jitters and all…. I’m really excited to be here. I mean, at a wedding. Any wedding. It just so happens to be your wedding…. I don’t know, I just feel like this is going to be one for the ages. I’m really happy I got to see it…. [Grabbing Barry’s wrist] Good luck up there. Remember to say, ‘I do.'”

Episode 11, surprising Cisco and Ralph by paying for their Jitters order: “Always pay it forward. That’s my motto, you know. Because at any given moment, one of us could need a helping hand…. And you know, it’s more than just karma. It’s the principle of infinite consequence at work in our lives. And it’s always expanding, creating positive sums on an infinite basis. isn’t that amazing?!” [She playfully punches Cisco’s arm after he compliments her “Oregon Trail” T-shirt. As Cisco and Ralph leave, the Waitress excitedly scribbles in a diary — using Speed Force symbols!]

Episode 15, again at Jitters, interrupting Caitlin and Harry’s conversation about Killer Frost by spilling a drink: “Oh my gosh, I’m so sorry. It just slipped out of my hands… My first Killer Frost [beverage] and I go and ruin it. I just get so clumsy when I’m nervous…. I’m supposed to be meeting some people here for the first time and I’ve got the jitters, which [Laughs] is what this place is called.” [To self, after Caitlin says she hopes the Waitress’ “meeting” goes well] It did.

Want scoop on The Flash, or for any other show? Email InsideLine@tvline.com and your question may be answered via Matt’s Inside Line.

Launch Gallery: The Arrowverse's Best & Worst Unmaskings

Related stories

The 100 Season 5 Trailer: Clarke & Co. Go to War With a Terrifying New Enemy

Black Lightning Recap: I'm Not Gambi, Dammit! -- Plus, Lightning Crackles....

The Flash Star, EP Talk Iris' Return to [Spoiler], Harry's 'Disastrous' Decision

Get more from TVLine: Follow us on Twitter, Facebook, Newsletter