Jessica Parker Kennedy is returning to The Flash. In the four part crossover "Crisis on Earth-X" a lot happened in the Arrowverse. Nazi doppelgangers of Arrowverse characters showed up on Earth-1 and targeted the various heroes who were conveniently all in one place for Barry and Iris' wedding. Between the death of Martin Stein, the appearance of Earth-X counterparts of Tommy Merlyn and Leonard Snart, and the eventual weddings of Barry and Iris, plus Oliver and Felicity, there was a lot going on. Still, audiences could not help but notice a new face in the crowd: a waitress at the (first) wedding, played by Jessica Parker Kennedy.
Her scene was a short one, technically occuring during the Supergirl portion of the crossover. She walked up to Barry moments before the ceremony to offer him a drink. She seemed to be more nervous than Barry was, and incredibly excited about the wedding, which she described as "one for the ages." Her enthusiasm was intense enough for Barry to ask if they had met before. She said no, but took his hand and intently reminded him to say "I do" when the time came. And then she walked away. Many fans theorize that she is either Barry and Iris' daughter or granddaughter and had time traveled back to 2017, but the character had no name and as of now, it's only a theory.
Now it sounds like fans will get their answer soon. In a phone interview with Bustle, Kennedy said she would be back in the Arrowverse at least once more. She's filmed an episode of The Flash that will air in the second half of the season. While hopefully her identity is revealed during that appearance, there is no guarantee. Kennedy says the character is shrouded in so much mystery that she is referred to only as Mystery Girl - even when talking to members of the cast and crew.
Fans might recognize Kennedy from her previous roles on 90210, Colony, and Black Sails. She says she never had to audition to play Mystery Girl, the producers offered her the role and filled her in on the plans. She also says that she doesn't pay attention to the fan theories, but she is excited that fans are so curious about her character and are trying to guess who she is.
Last season, fans guessed Savitar's identity very early in the season, so it is possible that the writers are teasing an obvious answer - the future daughter or granddaughter of the West/Allen relationship - while actually setting up something entirely unexpected. However, since current fan theories are based around the comic books, it does remain likely that she is someone from the future who is close to Barry. With the midseason premiere coming up soon, hopefully audiences will not have to wait long until the enigma of Mystery Girl is solved.
The Flash returns to The CW Tuesday January 16 at 8 pm.