Jonathan pulls Nancy back through the portal and saves her from the monster. Quite traumatized by the experience, she asks him to stay the night with her. Later, Steve sees them together through her bedroom window and assumes they are dating. Nancy and Jonathan resolve to kill the monster and purchase supplies from an army surplus store. Steve and his friends confront them there, and it comes to a fist fight between Steve and Jonathan, during which the latter inadvertently assaults a police officer and is arrested.
In the aftermath of getting knocked out by Eleven, Lucas is furious with her and Mike, and declares he is going to search for Will on his own. Dustin tries to encourage his friends to settle things between them, but to no avail.
Hopper meanwhile meets up with Joyce, and shares what he has learned so far with her. The two realize that the child from the laboratory is not Will, but is undoubtedly connected to the case. They track down Terry Ives, who is catatonic and tended by her sister Becky. Becky explains that Terry underwent Project MKUltra testing while unknowingly pregnant; she believed her daughter Jane was kidnapped by Brenner at birth. Joyce and Hopper conclude Eleven is likely Jane.
Eleven shoplifts Eggo waffles. She recalls being asked to contact the monster and accidentally opening the portal to the Upside Down in the laboratory basement.
While searching for Eleven, Mike and Dustin are ambushed by school bullies Troy and James. Troy holds Dustin at knifepoint and demands Mike make a suicidal jump into the lake where Will's body was discovered. Mike jumps but is levitated to safety by Eleven, who scares away the bullies.
Lucas, meanwhile, scopes out the Hawkins Laboratory from a vantage point. He sees a fleet of Hawkins Power and Light vans leave the lab and realizes that his friends are in danger.
This episode provides examples of:
- Big Damn Heroes: Eleven rescuing Mike and Dustin at the quarry.
- Catch a Falling Star: Eleven catches Mike with her mind.
- Cock Fight: Jonathan and Steve get into a fist fight over Nancy. Steve goads Jonathan into it by insulting his family, so it's not really all about Nancy, but that doesn't stop the woman at the police station from assuming this trope.
- Defacement Insult: Tommy and friends are going around spraying anti-Nancy-and-Jonathan graffiti around town due to their being Mistaken for Cheating. They haven't attacked their personal property — not yet, anyway.
- Evil Gloating: Inverted. Dustin is beside himself with glee after Eleven's Big Damn Heroes moment and gloats to the bullies that his dreaded friend will kill them if they come back.
- Friend Versus Lover: Dustin says that Lucas feels a rivalry with Eleven because she's absorbing Mike's attention, for more-than-friendly reasons.
- Green-Eyed Monster: While Steve has been rather shallow and self-absorbed up till now, he didn't turn outright cruel until he thought that Nancy was cheating on him with Jonathan.
- Group Hug: Of Mike, Eleven and Dustin at the quarry.
- Hairpin Lockpick: Nancy's mother uses her hairpin to open Nancy's room after her knocking remains unanswered.
- Humans Are the Real Monsters: This episode stresses that while the monster is a deadly and frightful being, it's still little more than an animal. Humans, on the other hand, can be downright EVIL. Fittingly, each of the episode's primary problems and conflicts are shown to be caused more by humans than the monster:
- The monstrous cruelty and ruthlessness of Brenner and the agents of the Government Conspiracy is revealed when Hopper and Joyce meet Terry Ives, left catatonic after being exploited and experimented on by the US government and having her child (Eleven) stolen;
- Troy's bullying towards Mike and Dustin reaches a vicious peak when he holds Dustin at knifepoint and threatens to cut out his teeth unless Mike jumps off a tall peak into a quarry;
- Steve is spitefully willing to slander Nancy purely out of jealousy and rage when he believes her to be cheating on him with Jonathan, rather than asking her for the truth, and in turn Jonathan is revealed to have a savage, uncontrollable violent side when Steve pushes his Berserk Button once too often;
- Eleven, after thinking she's been abandoned by her new friends, seems to be slipping into Then Let Me Be Evil by stealing food from a grocery store and uncaringly using her powers to hurt the harmless employee who tries to stop her.
- Hypocrite: After the barely-veiled hints about Carol's sexual appetite, her engaging in Slut-Shaming towards Nancy is more than a little rich.
- I Am a Monster: Said verbatim by Eleven because she feels personally responsible for having opened up the gate to the Upside-Down and made first contact with the monster. This is a Meaningful Echo to the previous episode where Lucas accused her of indeed being the monster, upon which she attacked him and ran away. Mike assures her that she is not the monster.
- Jerk with a Heart of Gold: Or a "Heart of Slightly Lesser Jerk", at least; after goading on Steve and Jonathan's fight, when it starts going badly for Steve Tommy tries to stick up for his friend and enter the fray on Steve's side, but is pushed away. He can also be heard pleading for Jonathan to let up on his No-Holds-Barred Beatdown and protesting that Steve has long since stopped offering any meaningful resistance.
- Ladykiller in Love: Much as he tries to deny it, Steve is clearly this when it comes to Nancy.
- Let's Get Out of Here: One of the two bullies says this before running away from Eleven at the quarry.
- Lock-and-Load Montage: Lucas gets one when he sets out to save Will on his own.
- Mistaken for Cheating: When Nancy and Jonathan come back from the encounter with the Demogorgon in the woods, Steve catches them in an apparently compromising position and assumes she's cheating on him.
- Mugging the Monster: Steve taunting Jonathan about his family ends up being this; for all his cockiness and swagger, he turns out to be woefully unprepared to face a genuinely pissed-off Jonathan out for blood. Downplayed, in that it's just being outclassed in a teenage punching match, but Steve nevertheless leaves the fight looking much less pretty than when he entered it compared to Jonathan.
- Mystical Pregnancy: It's implied that Terry Ives's daughter somehow acquired supernatural powers due to Terry subjecting herself to Mad Scientist experiments while pregnant.
- Never Split The Party: Dustin urges his comrades to stay together by reminding them of a tabletop mission where they were taken out one by one by the enemy because they decided to split up.
- No-Holds-Barred Beatdown: Jonathan gives an epic one to Steve for insulting his mother and brother. His rage eventually becomes so primal that he continues to pound Steve's face as he's being pulled off of him by police... and then punches a cop just so he can continue punching Steve.
- Plummet Perspective: When Mike steps towards the edge of the quarry, a small rock plummets down.
- Prompting Nudge: Dustin has to prompt Mike this way when they both stand in front of Lucas. Mike can only grudgingly bring himself to apologise.
- Rage Breaking Point: Jonathan genuinely tries to be the bigger man and walk himself and Nancy away from Steve's insults, and even manages to impressively put up with some very nasty comments about his family... but it's when Steve unwisely brings up Jonathan's (possibly, and as far as Steve knows actually) dead brother as a taunt that he just snaps.
- Sarcastic Confession: The army surplus store clerk raises an eyebrow at the weapons Nancy and Jonathan are buying. When he asks what they are up to, Nancy point-blank tells him they are going monster hunting. He makes the sale.
- Shower of Angst: Nancy takes one after her ordeal in the forest.
- Shrine to the Fallen: Terry Ives kept the room of her daughter Jane the way she decorated it 12 years earlier.
- Sickening "Crunch!": Heard when El breaks Troy's arm at the quarry.
- Slut-Shaming: Done to Nancy by Tommy and Carol, with the connivance, at least, of Steve, after Steve finds Nancy with Jonathan.
- Stupid Sacrifice: Mike jumps off a cliff into a quarry lake to prevent Tory from cutting out Dustin's teeth, which we learned in an earlier episode would be fatal, while Dustin himself points out that he can live without his baby teeth. However, this may be justified in that it's not clear that the boys know that this will kill Mike. The Soft Water trope was even more prevalent in media then than it is now, and at least one person in Hawkins has spread the story that he survived the jump.
- Symbolically, it also reflects their earlier conversation where Dustin revealed that he believed that he was a lesser friend of the others because they'd known each other longer than he had, and Mike had to reassure him that Dustin was one of his best friends. Foolishly, consciously or not, Mike is reinforcing that Dustin is as much his best friend as the others and that he is willing to die for him if necessary.
- Then Let Me Be Evil: Implied. Eleven after being treated like a monster finally decides to steal food in a supermarket and hurts an employee who was trying to stop her.
- There Is Only One Bed: Jonathan stays the night in Nancy's room and volunteers to sleep on the floor, but she invites him onto the bed shortly thereafter. He sleeps above the covers, though.
- The Tooth Hurts: The bully threatens to cut out Dustin's baby teeth.
- Unflinching Walk: Eleven displays some fine badassery walking away from the supermarket as glass doors crash behind her.