'Supergirl': What's Next for Sam After "Not Kansas"?

Tonight's episode of Supergirl saw Kara make the decision to leave Earth in favor of her former home on Argo, but that decision came with a big status change for Sam -- one that begs the question of what's next for Sam and the Worldkiller Reign.

Spoilers for tonight's episode of Supergirl, "Not Kansas", below.

"Not Kansas" picked up right where "Dark Side of the Moon" left off, with Kara/Supergirl (Melissa Benoist) returning to Earth just as Reign broke free of Lena Luthor's (Katie McGrath) restraints. Supergirl kept Reign busy long enough for Lena to synthesize the special Kryptonian rock Supergirl retrieved and in an instant, it appeared the heroes had won the day Reign quite literally separated from Sam (Odette Annable) and disappeared. With Reign vanquished, Sam was able to go home with her daughter and Kara was able to leave Earth for the remnants of her native world.

However, in the last moments of the episode that great triumph appeared to be in doubt. On Argo, Selena (Anjali Jay) and her devotees steal Kara and Mon-El's (Chris Wood) ship, using it to return to Earth. They're met by Thomas Coville (Chad Lowe). A new Fortress of Sanctuary begins to emerge from the ground and as it does, Sam is suddenly shaken from her peaceful normal life, dropping a glass as it's hinted that the arrival of Selena is calling back Reign even as Supergirl and Mon-El are trapped on another world.

So, what's next for Sam? From what we've seen of official synopsis for both next week's "Make it Reign" and the upcoming season finale "Battles Lost and Won" it appears that the focus is going to be on Selena, but that doesn't mean Reign is gone. Selena's arrival could signal a rebirth for Reign though one could argue that it won't be quite so easy for the Worldkiller this time around. It's entirely possible that Sam will fight back to prevent Reign from being part of Selena's grim plans for earth. It's a possible redemption that Annable herself has hinted previously, though she didn't rule out a happier ending.

"Maybe I'm being optimistic when I say that I think that there is a way to separate the two," Annable told ComicBook.com last fall. "I don't know how. I don't know if it's possible. I don't know what the stronger storyline would be. Because I certainly see -- and this is all just me taking random stabs here, because I really don't know what's gonna happen -- but I do think that there's strength in Sam giving up her life to do what's good for humanity, then having Reign gone. I also think that having a redemption arc, of a sort, or having Sam, saved especially for her daughter, I think would be a really nice ending. So, I'm gonna go with that one."

However, tonight's episode also gave a tease that, perhaps, a long-standing fan theory might become reality. Early on fans have believed that Reign would end up dead or imprisoned and, thus, Alex Danvers (Chyler Leigh) would end up adopting Sam's daughter, Ruby (Emma Tremblay). While Ruby went back to her mother once it appeared that Reign had been defeated, we see Alex wistfully looking at her photos with Ruby before looking up adoption agencies. It's possible that, now that Selena is coming to Earth potentially to bring back Reign, Alex could still end up Ruby's guardian. It's a possibility that Annable seemed to think that Sam would want.

"If something were to happen to Sam, I would definitely give [Alex] that blessing -- especially now that Alex and Ruby have this great connection," Annable said earlier this year. "Of course, that could happen, or it could not happen. We'll see!"

Will Sam be the key to stopping Selena or will Reign return as a Worldkiller once again? Fans will just have to stay tuned to find out.

Supergirl airs Mondays at 8/7c on The CW. "Make it Reign" airs next Monday, June 11th.