SPOILER WARNING: This article contains major spoilers for “Both Sides Now,” the latest episode of Supergirl.
The jig is up! The news is out! In "Both Sides Now," the latest episode of Supergirl, Lena Luthor realized her good friend Sam Arias is actually Reign the Worldkiller. Lena was able to piece the evidence together when Sam returned from another one of her blackouts.
Early in the episode, Lena told Sam to take a break from her role at L Corp. Sam took Lena's advice and used her time off to take her daughter Ruby ice skating. However, when Ruby's back was turned, Sam's Reign identity emerged. Reign disappeared from the skating rink, leaving Ruby by herself. Afraid and alone, Ruby called Lena, who showed up and took the girl back to her apartment.
Sam wandered by into L Corp later that evening. Disoriented, she asked where Ruby was and if her daughter was safe. Lena told Sam what had happened and revealed that Ruby told her about Sam's other blackouts. At this, Sam assumed Lena had told Ruby her mother was sick. Though Lena tried to explain this wasn't the case, Sam experienced a fit of rage, causing Reign to resurface momentarily. Sam's eyes flashed red and -- with a booming voice -- she cried, "Silence!" as Lena looked on.
Though the episode passed quickly, Lena pieced together the truth: Sam is Reign. When Sam returned to herself, Lena didn't seem afraid. In fact, she told Sam she knew what was wrong and that she would help her find a cure.
At this point, only Lena knows the truth about Sam, and it's unclear if she plans to share that information with Kara and Alex Danvers. However, over the course of the episode, Supergirl and the DEO realized that a Worldkiller's personality overtakes their humanity, as was the case with Julia Freeman and Purity. As such, it's likely only a matter of time before Team Supergirl tracks down the human persona behind Reign.
Returning later this year 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.