Sam is forced to confront the truth about herself, while M'yrnn's dementia worsens.
Tropes:
- Ambiguous Situation: It's not stated which one of the two unnamed White Martians is breaking out this episode.
- Batman Gambit: Lena deliberately provokes Sam's anger so Reign will emerge. The Kryptonite she's wearing disables her, and the cameras recorded everything so Sam will be forced to accept the truth of her condition.
- Borrowed Catchphrase: "Suit Up" finally makes it to Earth-38 when Winn announces to Mon-El he fixed his costume.
- Boxing Lessons for Superman: Or rather 'How to use your Cape as a weapon' lessons from Mon-El to Kara.
- Brutal Honesty: The "The Reason You Suck" Speech detailed below was on Kara's mind the entire time, but Myrnn's psychic breakdown is what finally makes Kara spill the beans.
- The Bus Came Back: Several of the imprisoned aliens are freed by M'yrnn's psychic rampage.
- Cruel to Be Kind:
- J'onn is loath to inhibit his father's mental abilities when that is all that kept him going for hundreds of years, but the alternative is having M'yrnn's breakdown put himself and everyone around him in serious danger.
- Lena accuses Samantha of being a bad mother, a monster and threatens to never let her see Ruby again, in order to have Reign break through and give Samantha hard evidence of her inhabiting her body.
- Harsher in Hindsight: An In-Universe example. When J'onn talks about his reluctance to treat his father's dementia by restricting his autonomy, essentially reducing him to a child-like state of dependence on his own son, Kara replies with a much darker take on a familiar Superman quote:Kara: My uncle Jor-el used to say, "the son becomes the father, and the father becomes the son."
- Hate Plague: The effects of M'yrnn's Power Incontinence. Everyone without some form of psychic shielding starts attacking each other.
- He Cleans Up Nicely: Mon-El says this verbatim about himself in his Legion uniform.
- Madness Mantra: M'yrnn's prayer quickly becomes this, as he desperately tries to control his powers, but unwillingly causes havoc.
- My God, What Have I Done?:
- Samantha is absolutely horrified after finding out that she is Reign.
- Same for M'yrnn, who is so torn up about the destruction he caused that he lets J'onn use his power dampener on him.
- Kara says this after yelling at Mon-El. However, this gets played with later on as she admits to meaning what she said.
- Mythology Gag:
- Kara quotes "the son becomes the father and the father the son" to J'onn (and directly attributes it to Jor-El, too).
- J'onn's imaginary friend Zook was a character in Silver Age Martian Manhunter stories.
- Mon-El's uniform stitching gives a vague, but empty, pentagon on his chest, like Kara's but without a house glyph.
- When she's summoned to the alien bar to deal with a disturbance, Kara slowly begins unbuttoning her shirt, rather than ripping it open to expose her Supergirl costume like she usually does (including in the regular opening montage). Alex looks at her askance to which Kara replies, "What? I like this shirt!"
- This isn't the first time a super-powered Kryptonian has been captured in action by a photo booth (and has walked away with the photos).
- Never Trust a Trailer: The trailer for this episode made it seem like Pestilence was the cause of the episode's problems. She's mentioned, but doesn't actually show up at any point.
- New Powers as the Plot Demands: Following his demonstration the preceding episode, Mon-El begins to train Kara in how to fight using her cape, which we learn is made from a special Kryptonian material with properties and abilities never before even hinted at in the series.
- No-Holds-Barred Beatdown: J'onn delivers an epic one to the White Martian. It never stood a chance.
- Noodle Incident: Pam from HR is very mad at Winn for some reason, but we don't find out why.
- Oh, Crap!: Winn's reaction when he sees Pam from HR coming at him with murder in her eyes. Also, Mon-El and Supergirl when they come across a flock of dead pigeons and realize that Pestilence is coming.
- Person of Mass Destruction: Similar to Charles Xavier in Logan, M'yrnn shows what an absolute nightmare a combination of powerful psychic abilities and a neurodegenerative disease is.
- Photo-Booth Montage: A violent yet hilarious one. Kara's battle with the Kalanorian ends when both fighters fall into a photo booth, the booth snapping photos as they wrestle inside. Kara grabs the photo strip after tossing out the Kalanorian.
- The Plague: Pestilience hasn't been found, but plagues are already starting to manifest. There's a river of blood in the arctic and birds drop from the sky in National City.
- Power Incontinence: Thanks to his dementia, M'yrnn's psychic powers inadvertently project the anger of his situation to anybody else near him.
- Power Nullifier:
- The DEO's psychic shielding technology is adapted to block M'yrnn's psychic powers, both to shield the minds of the DEO staff and in a stronger wristband meant to seal his powers. The former is eventually overloaded by the sheer strength of his mind, but he's convinced to put on the latter not long after.
- Mon-El's Legion ring serves as a psychic blocker.
- "The Reason You Suck" Speech: Under the influence of M'yrnn, Kara delivers a blistering one to Mon-El, calling out his attitude, selfishness and that he didn't deserve to be given such a break over all his behavior in the previous season. More telling is that after everything is settled, Kara admits that while it drove her to say it, she meant every word.
- Self-Serving Memory: Kara admits that she was seeing much of her relationship with Mon-El in far better terms to remember him better, but now faces up to his issues.
- Swapped Roles: Back in Season 2, Kara used to mentor Mon-El, now he is teaching her how to fight.
- Tomato in the Mirror: Samantha finally finds out about her being Reign.
- Troll: M'yrnn jokes about having a game with J'onn's childhood Imaginary Friend, which initially causes the latter to think his father's condition is getting worse.J'onn: That's not funny.M'yrnn: *grinning* Only because you couldn't see your face.
- What the Hell, Hero?:
- Samantha calls Lena out for caging her, keeping her from her daughter and accusing her of being Reign, assuming that, as a Luthor, she's conditioned to see "being a supervillain" as the answer. Lena has to brutally awaken her to the reality of her situation, at which point Sam is a lot more understanding.
- M'yrnn gets quite angry with J'onn when he tries to give him a device that will shut down his powers.
- Whole-Plot Reference: M'yrnn's condition and its effects mirror Sarek's condition from the Star Trek: The Next Generation episode "Sarek".
- Written-In Absence: Imra and Brainy are investigating the river of blood in the Arctic.
