When we last saw Supergirl/Kara Danvers/Kara Zor-El/Girl of Steel (Melissa Benoist), in Season 2’s penultimate episode, “Resist,” she was on the wrong end of a super punch from none other than Superman/Kal-El (Tyler Hoechlin). Under Rhea’s (Teri Hatcher) control (no) thanks to silver Krpytonite (if you didn’t know silver Kryptonite existed, you’re not alone), Superman doesn’t see Supergirl; he sees his greatest, all-time foe, General Zod (Mark Gibbon). After a mutually semi-destructive pounding aboard Rhea’s flagship, Supergirl and Superman find themselves back in National City, kicking, punching, and throwing each other around a water fountain. Somehow, Supergirl gets the better of her more famous cousin, knocking the noxious effects of silver Kryptonite with one, final super punch. It’s called Supergirl and not Superman, after all.
That’s not the end, of course. That’s just the beginning of Season 2’s final episode before it goes on hiatus for the summer. While Supergirl wins the fight, she’s battered, bruised, even uncertain of herself. After All, Rhea and her Daxamite fleet are still hovering over National City and nothing, not even the Justice League of America (because it doesn’t exist in the Supergirl universe, apparently), can stop the Daxamite invasion from taking over a few corners and alleys of National City and eventually the world (TV budget, as always, willing). Supergirl does what only a super-human would do: She challenges Rhea to personal combat, winner take all (the “all” refers to our world). If Supergirl wins, Rhea agrees to give up her plans for world domination and take her people elsewhere. if Rhea wins, Supergirl will bow before her in Zod-like fashion and watch Rhea turn the Earth into a fascist dystopia.
Luckily for Supergirl, she has not only Superman in her corner, but Cat Grant (Calista Flockhart), the Embodiment of the Feminist Ideal, to give her the Mother of All Pep Talks, before she goes out to meet Rhea on a rooftop for the equivalent of Alien Fight Club. Rhea claims she’ll fight fair and square, but she’s a royal, a queen who’s already killed her husband and willing to kill as needed to secure her reign on Earth or elsewhere. Unbeknownst to Supergirl, Rhea has an ace up her spandexed sleeve: She’s been contaminated by green Krptonite, meaning the first time Supergirl draws blood, Rhea will bleed green blood, not red. Supergirl has a back-up plan of her own: If she loses, Lena Luthor (Katie McGrath) and her alien-hating mother, Lilian (Brenda Strong), will unleash a weapon so powerful, it’ll make the Daxamites leave Earth and never come back: It’ll seed the Earth’s atmosphere with the one metal, lead, that can kill Daxamites. Just one problem with that plan: It also means Supergirl’s boyfriend, Mon-El (Chris Wood), a Daxamite Prince, will have to leave too.
It was bound to happen, of course. It was always unlikely Mon-El was going to stick around for more than a season. Supergirl’s producers could have easily offed Mon-El via the usual self-sacrificing stunt, but instead decided to go the comic book route: After a tearful, heartfelt good-bye, Mon-El jumps into the Kryptonite space pod that initially brought him to Earth and heads back into space, his fate uncertain as his space pod enters what looks like a wormhole, likely to be never seen again, let alone mentioned after one or two episodes next season. Mon-El’s seemingly permanent departure , of course, clears the romantic field for Supergirl next season. She’ll be free and clear of Mon-El and after a suitable period of (offscreen) morning, back in the dating world. And with romance all around her, including her adoptive sister, Alex (Chyler Leigh), proposing to her not-quite-longtime girlfriend, Maggie Sawyer (Floriana Lima), it looks like Season 3 will, at minimum, feature a wedding.
Kara’s close and personal friends, including Winn Schott (Jeremy Jordan), and onetime almost boyfriend James “the Guardian” Olsen (Mehcad Brooks), will also continue to have her back, as will Cat Grant, albeit in a limited capacity, popping in every few episodes (maybe) to drop some truth bombs on a a skittish, self-doubting Kara. She’ll also have her career as a reporter to cultivate, plus an an-all new super-human threat in Season 3: A pre-destruction-of-Krypton flashback reveals that Kara Zor-El and Kal-El weren’t the only survivors of Krypton. Another child also escaped Krypton’s destruction and all signs point to Kara’s – and possibly Kal-El’s – doom. Or maybe it’s all a bait-and-switch meant to distract viewers (it’s been known to happen) and Season 3’s Big Bad is someone or something else entirely.