When Mon-El returns to Supergirl, he won't be alone. Following the announcement of Saturn Girl's casting in September and -- later on -- the addition of Brianiac-5, The CW has made it official: the Legion of Super-Heroes is headed to National City. During a set visit, the Girl of Steel herself Melissa Benoist teased Supergirl's reaction to meeting the Legion, as well as her reunion with Mon-El.

"I don't want to tease too much, but the fact that the Legion is coming to the show has such a hold in the comic book world, especially with Superman, Martian Manhunter, specifically. That's really exciting for us," Benoist shared. "For Kara, it's a brand new set of problems that you'll see pretty quickly."

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"We've only just introduced the two of them, what we're working on now. I can't really tease anything. I think my lips have to be sealed on that one," she added.

As to Kara's reunion with Mon-El, Benoist promises it won't be what fans expect. "In Episode 7, it's pretty mysterious. I think this season, we've really delved into a different tone, a different atmosphere for Kara," she explained. "She's really figuring out how to own her alien-ness, if you will, and in turn I think she's finding her womanhood at the same time through grief and that grief is apparent even in the coloring of the show, so I think it's a long -- it won't be the reunion you expect."

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The Legion of Super-Heroes’s existence in Supergirl's reality was initially teased in the show’s first season, when viewers saw a Legion flight ring on display in Superman’s Fortress of Solitude. The teases continued following the Season 2 finale, when series star Melissa Benoist stated in an interview that the Legion Ring would make its return at some point. Additionally, Mon-El -- a character frequently associated in DC Comics with the Legion of Super-Heroes -- became a major part of the show as of Season 2, as played by Chris Wood.

Airing Mondays at 8 p.m. ET/PT on The CW, Supergirl stars Melissa Benoist as the Girl of Steel, David Harewood as Martian Manhunter, Mehcad Brooks as Jimmy Olsen, Chyler Leigh as Alex Danvers and Jeremy Jordan as Winn Schott, with appearances by Calista Flockhart as Cat Grant and Tyler Hoechlin as Superman.