Warning: spoilers ahead for Episode 13 of Supergirl Season 3, called "Both Sides Now."
The third season of Supergirl has been building the mystery of Reign from almost the very beginning. While viewers already know that Sam is secretly (and unknowingly) acting as Reign during her blackouts, Kara and Co. have been completely in the dark about Sam's double life. In "Both Sides Now," the line between Sam and Reign blurred at the exact wrong moment for her, and none other than Lena Luthor may be in on her secret. Lena reaction may could point to her embracing her darker side in a very dangerous way throughout the rest of the season.
Here's what happened. Lena told Sam to take time off to deal with her current problems, and Sam decided to take Ruby ice skating. Unfortunately for poor Ruby, Reign had a mission to retrieve a second Worldkiller, and Sam had to go do villain duty, which resulted in her abandoning her daughter at the rink. Ruby called Lena for help, and Lena kinda sorta spilled the beans that something is wrong with Sam.
When Sam finally turned up again, she confronted Lena about how much she told Ruby, and Sam was a lot more confrontational that usual. When Lena tried to make her case about her chat with Ruby, Sam bellowed "SILENCE!" and her eyes flashed red for a couple of seconds. Lena definitely noticed that her pal's eyes went red. When Sam came back to herself with no knowledge of what had happened, Lena assured her that she knew what was going on and she would take care of Sam.
On the one hand, huzzah for Lena for being a good friend and smart woman for seemingly connecting some dots regarding Sam's blackouts and red eyes! Although the episode didn't make it absolutely clear that Lena had realized Sam is Reign, the odds are pretty good that Lena figured out what's going on, and Sam may finally have an ally.
On the other hand, Lena didn't exactly declare that she needs to talk to Supergirl or Alex or somebody qualified to the hunt for Reign. If she truly wanted to do the altruistic thing, Lena would have filled Supergirl in on what was happening. After all, Supergirl is renowned for having hope and faith in people. Surely Lena would believe that Supergirl would both contain Reign and help Sam.
Instead, Lena seems determined to keep the big secret in-house. She intends to take care of Sam/Reign, apparently without the help of her superpowered friend. This could point toward Lena finally beginning embrace her sinister side more fully. Lena has already gone dark in some troubling ways throughout Season 3. She attempted to kill a business rival and then came very close to allowing her mother to finish the job, for just two examples. Perhaps Lena is more like her mother (and brother) than we previously believed. It's quite possible that Lena could grow even darker if/when she discovers that Kara is Supergirl and has been lying for a long time. A team-up between Reign and a villainous Lena could be extraordinarily dangerous.
If Lena doesn't turn on her own, it's possible that the mysterious woman handling the Worldkillers will be able to influence her. After all, the woman activated Reign and seems positive that she can reprogram Julia's personality so that she's entirely Purity; perhaps she can reprogram the good side of Lena as well, even if Lena isn't a Worldkiller herself. If she discovers that Lena is interfering with Reign, she could be very motivated to step in, and Lena is a powerful enough figure that she'd be more useful alive as an ally than dead.
Throw in the fact that Supergirl introduced one of Lex Luthor's warsuits earlier in Season 3, and we could be heading toward a villainous Lena Luthor. Only time will tell. The bad news is that "Both Sides Now" was the last episode of Supergirl for quite a while. Legends of Tomorrow will be taking over the 8 p.m. Monday time slot on The CW for the next nine weeks while Black Lightning airs in Legends of Tomorrow's regular slot. Supergirl won't be back with a new episode until April 9. For your other viewing options in the coming weeks, be sure to swing by our midseason TV premiere schedule.