The revelation President Marsdin is an alien leaves her and Supergirl in serious political trouble. Brainy has to face up to an uncomfortable meeting with Nia.
Tropes:
- Arm Cannon: Lena uses an upgraded cannon against Mercy, but quickly becomes overpowered since she's just not a fighter.
- Beware the Nice Ones: Nia refuses to stand by while Massimo (the owner of the pizza parlor Brainy frequents) and his employees harass and attack Brainy, verbally tearing the man a new one for his actions.
- Call-Back:
- The lead dispersal bomb from the season 2 finale returns, stolen by Mercy and used to distribute kryptonite, per its original intent.
- Lillian's Lex-o Suit is being kept in Lena's experimental prototype storage. Mercy and Lena duel using the Arm Cannons, which Lena has made some upgrades to.
- Camera Spoofing: Using a hologram projector, Jensen makes it appear as if Mercy and Otis are still in their cells while the trio make their escape. Alex catches on because the holographic recording of Otis has a stutter in its loop as he paces in his cell, but they're gone by the time this happens.
- Catch and Return: Kara does this when a bunch of mooks open fire on her, Lena, and Eve. Since she's not in costume, she makes a show of falling over so she can toss the bullets back without it seeming like a deliberate action.
- Category Traitor: Mercy denounces both Alex and Lena as "Earth traitors" for helping aliens (or, in the case of Lena, choosing not to join Mercy's crusade against them).
- Cliffhanger: Mercy steals the lead dispersal bomb and modifies it to release Kryptonite, poisoning Kara and causing her to drop out of the sky.
- Coming-Out Story: Nia tells James she is transgender, while explaining why she'd stood up for Brainy since it had reminded her of transphobia.
- Continuity Snarl:
- The nature of Brainy's human disguise (that it's technology provided by L-Corp) is at odds with how it was explained in Season 3 (that it was either a device Brainy created or 31st century tech).
- During the attack on L-Corp, Kara declines to put earplugs in, despite the fact Mercy used a similar sonic weapon to incapacitate her in the previous episode.
- The Corrupter: Mercy tries to sway Lena to her way of thinking, to no avail. She has more luck with Agent Jensen.
- Cover-Blowing Superpower: Kara is stuck with Lena and Eve in L-Corp as Mercy raids the building, so she has to use her powers covertly to protect them.
- Does This Remind You of Anything?:
- The aliens being suddenly outed and people reacting to them violently as a result is not unlike how this can happen for trans people. Nia, who's transgender, explicitly makes the comparison while explaining why she felt the need to stand up for Brainy.
- Agent Liberty's rally, if you were to remove the few people of color there, is disturbingly reminiscent of a white nationalist rally. Even his reference to Marsdin being revealed to be a Durlan could be taken as an example of someone pushing the conspiracy theory that Barack Obama isn't an American citizen, since he doesn't use specific names when referring to Marsdin or her species.
- Don't Create a Martyr: Agent Liberty warns Mercy not to make Supergirl one when Mercy reveals she has a sample of Kryptonite.
- Dueling Hackers: Lena and Mercy pull this over the mainframe controlling the image inducers. Mercy manages to knock out Brainiac's copy, but Lena shuts down the system before Mercy can compromise the entire network.
- Face–Heel Turn: DEO Agent Jensen joins up with Mercy and Otis after a speech from Mercy convinces him that Alex would protect aliens ahead of humans. Given that all it seemed to take for him to make up his mind was seeing Alex be nice to Brainiac-5, Jensen was arguably never much of a face to begin with.
- Foil: Supergirl and Agent Liberty both act as heroes for their respective sides, and each give well-received speeches at the end of the episode, with Kara (an alien) urging people to have hope and live up to their better natures, while Agent Liberty (a human, as far as we know) plays on peoples' fears and prejudices, even encouraging them to stay afraid to fight against aliens. What's more, Supergirl proudly shows her face on national television as a public hero, while Agent Liberty wears a mask and holds private rallies.
- Foreshadowing: Otis brings up the lead dispersal bomb while noting how the DEO has killed its fair share of aliens, even betting that it's still in the building, so it's not much of a surprise that he and Mercy steal that on their way out.
- Glamour: We learn that Brainy's human-like visage is thanks to one of L-Corp's image inducers. This creates a small Continuity Snarl as when he first adopted human form in season 3, it was implied that the tech he used was either his own or from the 31st century.
- Glamor Failure: Mercy hacks L-Corp's image inducer network intending to deactivate them all. Luckily, she has to start with the first, being worn by Brainiac, and Lena is able to isolate the network before she can shut down the rest.
- Heroic BSoD: Brainiac is so shaken by the sudden change of behavior in the pizzeria owner that he is unable to calculate outcomes properly.
- Hidden Depths: Eve Tessmacher once again surprises everybody, this time by using a hairpin to short-circuit a jammed security door and force the backup system to finish closing it.
- Hypocrite:
- A few racist DEO agents take issue with President Marsdin being revealed as an alien, despite the fact that the DEO has regularly worked with one alien (Supergirl) with another alien (J'onn) having been the DEO's director until quite recently, and a third (Brainy) stepping in to Winn's shoes.
- Unsurprisingly, neither Mercy nor her mooks, despite their pro-human mission statement, have any problem harming humans; Mercy murders an L-Corp employee simply to steal his laptop, and her henchmen have no qualms about shooting at three apparently normal humans (one of whom was actually Kryptonian, but none of them were in a position to know that), even before Mercy denounces Lena as an "Earth traitor".
- Irony: As Supergirl broadcasts a message to promote tolerance, Agent Jensen is visibly stewing in hate and coming over to the Graves way of thinking.
- Know When to Fold 'Em: The revelation that the President of the United States is an alien has Marsdin facing both demands for her resignation and impeachment as well as huge protests across the country. She steps down and refuses a pardon to help defuse the situation.
- Meta Casting: Nia Nal turns out to be transgender, just like her actress Nicole Maines. The casting was planned this way to begin with, in setting up the first transgender superhero.
- Mythology Gag: This isn't the first time an imprisoned Otis has been replaced by a projection to delay the discovery of his escape.
- Non Chalant Dodge: Brainiac does this when one of the employees of the pizzeria swings a bat at him.
- Oh, Crap!: Brainiac, after being told that his image inducer disruption was caused by Mercy, immediately calculates that she is likely already attacking L-Corp to hit the servers directly.
- Politically Incorrect Villain: Apparently, a young Lex Luthor had something of a sexist streak; when Lena showed her brother her inventions, he'd call them "cute" and suggest she paint them pink.
- Pragmatic Villainy: Agent Liberty balks at the idea of using Kryptonite, not out of any moral issue, but because killing Supergirl would just make her a martyr for the other side. Mercy ignores him at the end of the episode by using it in the dispersal bomb.
- Rabble Rouser: J'onn comes to a public appearance of Agent Liberty rallying a crowd against aliens.
- Recycled Title: It's the third episode in the Arrowverse with this title after The Flash and Arrow.
- The Reveal: Nia reveals to Jimmy that she's transgender.
- Saying Too Much: Otis lets slip that Mercy is not his only accomplice when he says "the two of them" in reference to his at-large sister.
- Shaming the Mob: Nia does this to Massimo and his workers, who attack Brainy.
- Ship Tease: The Meet Cute between Nia and Brainy results in a bit of flirting on her part.
- Shout-Out: Mercy makes a reference to Game of Thrones, by claiming that "The web is dark and full of fun things."
- Slasher Smile: Otis has a nasty grin on his face when the dispersal bomb goes off at the end of the episode.
- Slave to PR: James is still under scrutiny after the whole Guardian affair and thus is reluctant to print a personal stance against the ongoing anti-alien sentiments, much to Nia's chagrin.
- Trojan Prisoner: Mercy planned to be captured by the DEO so she could steal the lead dispersal bomb from them, having researched their personnel and fingered Jensen, who is responsible for monitoring the cells, as someone she could sway to her side.
- Villain Has a Point: In-universe, much to Kara's shock, Lena says that she thinks Lex was right in that humans should be just as powerful as aliens. Kara doesn't get a chance to give her own opinion on the matter.
- We Used to Be Friends: Back when Mercy was involved with Lex, Lena saw her as something of a big sister. Not so much these days.
- What Measure Is a Mook?: Kara appears to avert her own "no kill" rule by catching a bunch of bullets fired at her by Mercy's mooks and then throwing them back at them with ballistic speed, mowing the men and women down. Since they're in tactical gear, we may be meant to presume they're wearing bulletproof vests which would save their lives, but the episode never follows up on their fates.
- White Sheep: For refusing to join Mercy's anti-alien crusade, Lena is denounced as unworthy of the name "Luthor". Supergirl responds that it's the other way around.
- You Just Told Me: Otis lets slip the fact that Mercy isn't on the run alone.
- Your Approval Fills Me with Shame: When being interrogated by Alex, Otis brings up the lead poisoning the D.E.O. used to get the Daxamites off the planet, laughing about it and complimenting her, much to Alex's dismay.
