Warning: spoilers ahead for the eleventh episode of Supergirl Season 3, called "Fort Rozz."
Supergirl has been building Reign up to potentially become Kara's most brutal foe to date, and the latest episode proved that even a group of superpowered opponents may not be enough to take her down. During a trip to Fort Rozz (which was located in a place hospitable only to women), Kara, Saturn Girl, Livewire, and Psi joined forces to fight Reign, and Reign escaped without taking any physically crippling hits. In contrast, the other women were very nearly stuck in space with no means of escape, and Livewire was killed in defense of Kara. Reign won't be easy to take down, and the end of the episode may have revealed a major character who will be her next main character target (other than Supergirl herself): Alex Danvers.
For most of the episode, Alex was having a pretty great time babysitting Ruby. Sam was scheduled to head out of town on a work trip when her babysitter flaked; laid up with a broken leg and with nothing to distract her, Alex offered to let Ruby stay with her. Alex and Ruby bonded in some pretty heartwarming ways that seemed to promise a fun friendship. Unfortunately and unbeknownst to Alex and Ruby, Samantha would end up going full Reign rather than embarking on her business trip. While attempting to take down Supergirl and Co. on Fort Rozz, Reign got a blast from Psi, and she saw visions of a clearly terrified Ruby. When Reign became Sam once more, she went to pick up Ruby and was shocked to discover that she was supposed to have been on a work trip. Panicking, Sam confided in Alex that she was losing blocks of time and didn't know where she had been for the past couple of days.
On the one hand, Alex seems poised to become an ally to Sam and Ruby moving forward. On the other and far more frightening hand, Ruby's attachment to Alex and Sam's decision to confide in her may have painted a big old target on Alex's back. The blast from Psi clearly knocked something loose in Reign, and Sam's realization that she didn't know where she'd been indicates that she may begin to investigate what's been happening to her. If Reign and Sam end up melding into one consciousness, that one woman may want to do just about anything to keep Reign's identity a secret. Alex is too smart (and too bored, laid up with her broken leg) to let Sam's confession go, and she's arguably the person with the most dots to connect about Sam being Reign. Sam/Reign may feel the need to take out Alex.
There's another reason why Alex might be in a lot of danger from Reign moving forward. Reign was very clearly confused after the vision of Ruby courtesy of Psi, and it stands to reason that Reign will use all of her formidable powers to prevent the reality of a terrified Ruby from coming true. If Ruby becomes scared of her mother, she could very well run to her new adult pal Alex for help. A confused Sam/Reign could therefore interpret Alex as a threat and do what's necessary to take her out. Normally, Alex would be enough of a badass to hold her own against a villain, at least for long enough for her super sister to lend a hand. Reign is no common Villain of the Week, however, and Alex is already injured with a broken leg. If she ends up as a big character to be targeted by Reign, she could be in a lot of trouble.
You can catch new episodes of Supergirl on Mondays at 8 p.m. ET on The CW. For more viewing options now and in the coming weeks, take a look at our midseason TV premiere schedule. Supergirl is going to be going through some scheduling changes moving forward, but there will still be plenty of superheroes on the small screen. For some interesting tidbits on the various DC Comics shows, take a look at our breakdown of superhero facts we learned at the big DC in D.C. 2018 event.