Oliver has finally found the mysterious Demon - his old mentor turned enemy Talia Al Ghul. With no other choice, they team up to stop Dr. Parker's deranged experiments.
- Ambiguous Situation:
- Talia's "old adversary" in Gotham goes unnamed, raising the question of who exactly she tangled with; Batman, who's been implied to exist on Earth-1 (Oliver having name-dropped Bruce Wayne in season six), Batwoman, who's been confirmed to appear in the Elseworlds crossover, or some other member of the Batfamily?
- Oliver apologizes to Talia for killing Ra's al Ghul, but given his previous lack of regret for doing so, it's unclear as to whether he's serious or just playing along with Talia's viewpoint to secure her aid.
- Armor Is Useless: Talia and Oliver easily fight off at least a dozen prison guards with heavy armor.
- Badass Boast:
- After Parker calls Oliver 4587 one too many times, he finally kicks his ass with an epic My name is Oliver Queen!
- When facing a dozen or so heavily armored guards, Talia smirks and asks Oliver whether he thinks they realize they are outmatched.Oliver: They're about to.
- Bad Guys Do the Dirty Work: Talia kills Dr. Parker after breaking free of prison.
- Beauty Is Never Tarnished: Despite the obvious burning marks, Talia still looks quite attractive.
- The Bus Came Back: Talia returns in this episode; as does Anatoly.
- Curb-Stomp Battle: Talia and Oliver utterly destroy every guard between them and the exit.
- Death of Personality: The point of Dr. Parker's experiments; he erases violent tendencies by erasing his subjects' entire identity, leaving them as an Empty Shell, if they survive the procedures at all.
- Debate and Switch: In the previous episode Dr. Parker made some genuinely valid points about Oliver's 11 year journey (though going to horrific lengths to achieve them), but the reveal that he's a Psycho Psychologist means these aspects never have to be truly explored.
- Enemy Mine: Oliver and Talia still resent each other, but (after some initial hesitations) agree to work together. When Oliver stays behind to buy some time and asks her to deliver the information to Felicity, there seems to be some sense of old camaraderie coming back.
- Expy: Parker's baldness, beard, Lack of Empathy, and career as a Psycho Psychologist makes him out to be one for Hugo Strange.
- Fate Worse than Death: Dr. Parker's experiments are so bad that Talia considers the accidental death of Diaz's associate during them a mercy for him.
- Foreshadowing: Talia mentions she got locked up in Slabslide as result of a run in with an old adversary in Gotham, setting up Batwoman's debut in upcoming Elseworlds crossover.
- Get Out!: How Oliver initially reacts to Talia offering him her help.Oliver: "So I'm asking you, however you broke into my cell...get out."
- Hallway Fight: Oliver and Talia vs. The SWAT prison guards. Pity the guards.
- I Choose to Stay: Oliver sends Talia to escape the prison alone, as it would only make him a wanted fugitive.
- Internal Reveal: Felicity learns from Stanley that Oliver is at Level 2.
- I Owe You My Life: Talia got involved with Diaz because one of his drugs saved her life after the explosion on Lian Yu.
- Knight Templar: Parker honestly believes that his inhumane experiments are actually helping his patients.
- Lack of Empathy: Parker, despite his claims of trying to help people, shows a distinct disregard for the lives of his subjects; he's mentioned as being responsible for the deaths of at least eight patients before setting up shop at Slabside, and when Oliver questions him on the death of another prisoner, Parker disapprovingly mentions it as "something the old you would say", showing no remorse or sympathy for the dead man.
- Laser-Guided Karma: Before she kills him, Talia puts one of his Shock Collar's on Dr. Parker.
- Lured into a Trap: Curtis' meeting with Malcolm Byrd goes this way. Fortunately, A.R.G.U.S. came prepared for it.
- Mad Scientist: Dr. Parker has some crazy ideas about how to rehabilitate prisoners, and some scary machines to help.
- Moral Myopia: Talia draws a moral equivalency between Oliver killing her father and the suffering inflicted on Oliver and his family by Prometheus. Oliver eventually apologises for Ra's' death, but it's unclear as to whether he genuinely considers himself in the wrong for killing him, or if he's just playing along with Talia's point of view to get her help.
- Mythology Gag: Robert Goodman, a former patient of Dr. Parker, shares the name of a writer/producer for various DCAU shows.
- No-Holds-Barred Beatdown: After being overwhelmed by their sheer numbers, Oliver is subjected to a painful beating by dozens of guards with batons.
- Non-Action Guy: What Curtis wants to be. After Oliver going to prison, he feels that he can't be Mr. Terrific anymore and also doesn't want to go into the field on A.R.G.U.S. mission. John manages to get him to change his mind later.
- Noodle Incident: Talia's capture at the hand of an old adversary in Gotham, mentioned above.
- Oh, Crap!: The sadistic guard at Level 2 has one when he realizes Oliver and Talia aren't wearing their Shock Collar anymore.
- One-Man Army: Diaz, after having taking the mysterious drug from last episode, apparently defeated dozens of heavily armed Bratva members offscreen.
- Pay Evil unto Evil: What Talia inflicts on Dr. Parker at the end of the episode.
- Prison Riot: One occurs near the end of the episode.
- The Reveal: Talia is the Demon. She survived the explosion of Lian Yu. Diaz rescued her as part of his crazy contingency plan to inflict pain on Oliver.
- Revenge Before Reason: Talia appears to be giving into this when she attacks Oliver in front of the guards. But it's just a ploy to get her and Oliver into the blue room.
- Shock Collar: Every inmate in Level 2 has to wear one, though it is put on the wrist, not the neck.
- Snark-to-Snark Combat: Dinah, Felicity and Laurel working together naturally creates some tension, especially coming from the latter, who keeps making snide remarks.
- Sympathy for the Devil: Despite the inmates in Level 2 being genuinely dangerous and unhinged criminals, Oliver still thinks that what Dr. Parker does to them is utterly inhumane. Special mention goes to Diaz's man with the Grim Reaper tattoo, who doesn't survive his treatment.
- The Un Twist: The Demon of Slabslide is... Talia Al Ghul; honestly who else would it be but a member of the Al-Ghul Family?
- Third Line, Some Waiting: The A plot is about Oliver and Talia working together in prison. The B plot is about Dinah, Felicity and Black Siren trying to uncover said prison's corruption. The C plot is about Curtis and John trying to apprehend a black market arms dealer named Malcolm Byrd.
- Took a Level in Kindness: Laurel lampshades hers; she describes empathy as "a word I'm learning".
- Villains Never Lie: Talia brings up this fact in regards to herself.
- We Used to Be Friends: Talia and Oliver both remind of each other how they used to be teacher and student. And at the end of the episode, it seems like that there is some kind of chance for reconciliation.
- Wham Line: Talia's line about facing off an old adversary in Gotham, which going off Oliver's comment that the moniker of Oracle was taken reveal that the Bat Family is indeed active on Earth-1.
- Wham Shot:
- Oliver seeing Talia in Slabslide.
- Diaz in Moscow holding Anatoly prisoner.
- What the Hell, Hero?: Well, 'hero' is stretching it a bit, but Oliver is still shocked that Talia would even consider allying herself with somebody like Diaz, as she used to have honor. Talia just shrugs it off.
- When He Smiles: When she and Oliver part ways, Talia actually gives him a little smile, implying that there might be a chance for reconciliation between them.
- You Monster!: Oliver calls Parker a monster after recognizing the full extent of his experiments. Parker doesn't even bother to challenge the assertion.
