Supergirl: Can Mon-El and Kara survive his deception?

Warning: This story contains major spoilers from Monday’s episode of Supergirl. Read at your own risk!

Supergirl officially unveiled who Teri Hatcher and Kevin Sorbo are playing during Monday’s episode — and it’s safe to say, they’re not big fans of the Girl of Steel.

When their mysterious spaceship arrived above Earth, Kara (Melissa Benoist) went to investigate, only for them to open fire on Supergirl. The inhabitants of the ship wanted one thing: Mon-El (Chris Wood), whom they’d use a tractor beam to bring aboard. But Kara tags along on the trip, discovering their true identities: Rhea (Hatcher) and Lar-Gand (Sorbo), the king and queen of Daxam — and Mon-El is the prince!

“Kara’s always waiting for the other shoe to drop in terms of relationships,” executive producer Andrew Kreisberg tells EW. “It took her such a long time to open herself up to Mon-El, and then was just starting to feel comfortable when she finds out that he’s been lying to her for these eight months.”

It doesn’t help that the Daxamites and Kryptonians are basically the Hatfields and McCoys — sworn enemies who could never see eye-to-eye — which leads to a pretty disastrous family dinner once aboard the ship. “It was one thing when she thought he was just a lowly guard on Daxam and was as much a victim of the tyrannical rule of the king and queen and prince,” Kreisberg says. “But then she finds out he was the prince, and that he was more of a perpetrator than a victim, and all of the great character strides he has made evaporate for her because she’s so put off by the truth.”

“It’s really heartbreaking,” Kreisberg continues, “because he really has changed. He really has grown and become a different person. But for Kara, it’s in the catchphrase, ‘Truth, Justice, and the American Way,’ it’s so important to her. It unravels their relationship as quickly as it began… and it really puts her whole worldview into dire straits.”

Suffice it to say, Kara and Mon-El are on the outs at the moment, which is made more complicated by the arrival of the Music Meister (Darren Criss), who whammies the Girl of Steel, trapping her in a movie musical that will be featured during The Flash on Tuesday. More details here.

In the meantime, Benoist teases that the Daxamites are very different villains than what we’ve seen with Cadmus. “They have an entirely different set of motives,” Benoist says. “They want their son back, and they have a completely different way of life on Daxam that wasn’t exactly morally sound. Cadmus has a very clear directive of what they want and how they’re going to do it, and it’s humans against aliens, and with Daxamites, it’s scary because it’s aliens against aliens, a lot like Non and Astra, and a powerful woman in Mon-El’s mother.”

“What’s interesting about Rhea is that she’s a calculating customer,” Kreisberg adds. “She’s very bright and believes in her own right to authority and really believes in this second chance that she thinks her planet has in finding Mon-El. The Daxamites who survived the cataclysm from Krypton’s explosion were scattered to the far ends of the universe, and she really believes that bringing Mon-El back, signaling a continuation of the ruling family and the new blood of the return of the favorite son, can really unite the planet. So she’s torn between her desire to reclaim her throne and her love for her son.”

Her love for Mon-El is exactly why Rhea is not a fan of Kara. “The big thing we talk about, as far as Rhea and Kara, is that it’s a little bit of Guess Who’s Coming to Dinner, where you have the theocracy, these slave-owners, these people who believe in power, whose son they believe is like-minded has been corrupted.”

Supergirl airs Mondays at 8 p.m. ET on The CW. Watch The Flash-Supergirl musical crossover Tuesday at 8 p.m. ET on The CW. Get behind-the-scenes scoop on the crossover here, check out photos here, and read our interviews with Darren Criss here, Grant Gustin here, Melissa Benoist here, John Barrowman here, Jeremy Jordan here and Carlos Valdes here.