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"The three will walk across the land and the blood of the weak will water the new world."
"Rao defies you. I defy you, and I will bring you low.
Purity and Supergirl

"Both Sides Now" is the thirteenth episode of the third season of Supergirl, and the fifty-fifth episode overall. It aired on February 5, 2018.




Guest starring[]



"Both Sides Now" starts with Kara and the DEO at the house of an affirmed Worldkiller. Winn shares that they have one heat signature within, and when Kara and Alex break the door to enter the home, they discover Julia Freeman — the woman we recently observed that was hit by a vehicle — in a back room.

Julia has no clue about why Supergirl and the DEO are in her home, and when a frightened Alex threatens to use her gun on Julia, the latter releases her powers against the group. Julia uses a sonic shout — much like Black Canary or Black Siren — yet J'onn is in the end ready to handcuff her.

Lena and Sam are talking at CatCo about Sam's ongoing activity execution. Lena shares that she's searching for extra assistance to help assume control over Sam's job, requesting the yet-to-be-uncovered Worldkiller to take a vacation day.

The group collects at the DEO, endeavoring to locate the command post for the Worldkillers. Mon-El, J'onn, and Winn disregard Kara and Alex. Kara admits to her more established sister that she's annoyed by how it looks like somebody took control over Julia's body.

Somewhere else, Mon-El approaches J'onn and Winn for their assistance in fixing the Legion ship so he and the remainder of the Legion can return to their time.

Kara and Alex stroll into Julia's holding cell to start a cross examination. Julia's eyes are as yet white, indicating that the Worldkiller persona is still in control. Julia uncovers her Worldkiller name is Purity.

While Kara is attempting to play "good cop," Alex steps in to assume the contrary job, taking steps to never let Julia out.

Sam gets Ruby from school so the two can both take an impromptu day off and go ice skating.

J'onn takes Mon-El and Winn to see his own ship, which acts like a covert convertible. Mon-El discloses to J'onn that the Legion ship has lost power, and J'onn offers the power source from his own ship to assist.

At the DEO, Kara attempts to get Purity to switch back to Julia. Kara utilizes a picture of one of Julia's friends from the past in order to lure Julia back, however the Worldkiller persona doesn't leave. Purity tells Kara her plans for killing her, and a displeased Alex pulls Kara outside, where the two quarrel over whether Purity can be redeemed.

The trio is chipping away at getting the battery to take a shot at the Legion ship. Imra strolls in, attempting to help, and a disappointed Mon-El gets in a strained second with her, and it's revealed that the two are at a rough point in their relationship.

Back at the DEO, Purity gets into Alex's head, who storms out of the room upset. Kara stands up to the Worldkiller about Alex being right.

Sam and Ruby are seen ice skating.

Winn's working in the lab when he sees an annoyed Alex pacing to and fro outside. Winn sees the power source from the Legion ship he's taking a shot at has turned on in the lab, and goes to examine.

Sam and Ruby are in a race at the ice arena when Sam's eyes turn red. Ruby pivots to converse with her mother, and Sam is mysteriously absent.

The ship's power source causes electrical problems that power down Purity's cell. Purity uses her power to break out of her holding cell and knock Kara out. She stands up to Winn and takes the force source from him before getting away from the DEO.

J'onn comes back to the Legion ship with a container of "Martian home brew" to impart to Mon-El. The Martian Manhunter shares with Mon-El that he too was married a few hundred years ago and offers to help. Mon-El opens up and uncovers that his union with Imra was basically an arranged political marriage.

Mon-El admits to J'onn that he avoids Kara now since despite everything he still has feelings for her, and Imra gets furious. J'onn says that marriage is "sharing," and urges Mon-El to impart his emotions to Imra so she comprehends what's happening. J'onn's telephone goes off, and the pair is made aware of Purity's breakout at the DEO.

Lena moves toward a distressed Ruby at the skating arena. Lena consoles Ruby that she'll find the answer to her mother's ongoing problems.

J'onn and Mon-El show up at the DEO a similar second Kara and Alex stroll in. Winn gives them four earpieces that would hinder Purity's sonic forces. Reign is at her Fortress and gets a request to discover Purity and bring her back there.

Purity is beginning to do a type of ritual on a train, and is before long Kara enters the train and the two start battling in the subway tunnel. Mon-El, Alex, and J'onn surround her, and in spite of the fact that the group is unphased by her powers because of Winn's new tech, Purity uses her powers on the ground and causes everyone to fall through the floor to the train station below.

The group starts battling in the tram station, causing many regular folks to run away. Kara and Purity battle while J'onn, Winn, and Alex center around saving the entirety of the regular folks from the harm caused.

Purity has overwhelmed Kara until Alex runs up and Julia begins to intermittently take back control of her body. Julia assumes full control and lets Kara go. Reign flies in and is going to murder Alex when Julia offers herself up. Reign takes Julia and flies away.

Rule has taken Julia back to the Fortress of Sanctuary to help her awaken.

On the Legion ship, Winn has fixed the force source and disregards Mon-El and Imra. Mon-El apologizes to his better half for the way he's been acting and concedes that being back by Kara is a mistake for him. Imra inquires as to whether he still loves Kara, and he concedes he doesn't know. Mon-El says he will work through it, yet Imra discloses to her significant other that it's at last time she reveals to him why the Legion is truly in National City.

Kara and Alex are out having a beverage. The two discuss about their issues with adoration and promise each other that they'll in the long run locate "the one."

Sam runs into Lena's office searching for Ruby. Lena uncovers that Ruby knows about all the times Sam has disappeared. An irritated Sam briefly turns into Reign, and Lena acknowledges what Sam's issue is. Lena consoles Sam that she's going to make her better.





  • Alex unusually gets trigger happy at the start. She points her gun at Julia in fear and demanded her to surrender; completely opposite of her normal cool and logical self. Just from Julia trying to take Kara's outstretched hand, to help her stand up.
  • Alex says, "Purity is down, Reign and Pestilence to go" before Julia identifies herself as Purity. At that time, Alex couldn't have known whether the woman they captured was Purity out of Purity and Pestilence.