In Justice League, audiences saw a lot of a civilian Russian family who, unfortunately, lived a little too close to Steppenwolf's base. Their home is surrounded by parademons and they are very much in need of a rescue.
While Barry Allen/The Flash (Ezra Miller) zooms in and saves the family from Steppenwolf's destruction, we don't get a lot of information about this family other than the obvious terror they experience being in Steppenwolf's back yard and the relief of being saved. However, because Justice League spent so much time coming back to this family and creating an emotional connection between them and the audience, some fans are speculating that the family is a hint at future additions to the DC Extended Universe, specifically the Wonder Twins.
In DC Comics, the Wonder Twins are the extraterrestrial twin brother and sister superheroes-in-training, Zan and Jayna. They first appeared in the animated The All-New Super Friends Hour, but were later introduced into DC's post-Crisis on Infinite Earths continuity as escaped slaves of an alien overlord. The pair have transformational powers with Zan able to transform into any form of water and Jayna able to transform into any animal.
While their comics origin might seem a little bit of a stretch for the Russian children to end up the Wonder Twins, it might not be too much of a stretch. First, the family was, in a sense, prisoners of an alien overlord. Steppenwolf's parademons surrounded their home making them prisoners while Steppenwolf brought the Mother Boxes together right by where the live. The proximity of the Mother Boxes themselves might also give an explanation to the children developing super powers should they indeed be the Wonder Twins. One of the powers the Mother Boxes possess is the ability to rearrange molecular structure of matter. Considering that Silas Stone used a Mother Box to turn his son Victor (Ray Fisher) into Cyborg and Batman (Ben Affleck) used one to resurrect Superman (Henry Cavill,) the idea of the boxes giving the kids transformational powers starts to seem very possible.
And the Wonder Twins have ties to the Justice League in comics, too. In the movie, the family is saved by the Justice League from Steppenwolf, but in comics the League also emancipates the Wonder Twins, though in comics they've inadvertently attacked both some civilians and the League due to not speaking English.
Of course, there could be other possibilities. Other theories posit that the little girl could grow up to be the Teen Titan, Terra -- which would be a nice touch should the DCEU ever do a Teen Titans movie -- or even Kara Zor-El, aka Supergirl, who did land in Russia instead of the United States in the DC Bombshells series.
Justice League is in theaters now.