When she discovers the truth about Zelena's feelings for Hades' from Regina, Cora suspects that her daughter is being played for a fool by Hades, so she makes a potion from the Lethe that would make Zelena forget about Hades. When Cora finally meets Zelena, this mother-daughter reunion doesn't go smoothly as planned, and even Zelena is on to what they did with the water from the River Lethe they put the spell on, as she turns down her mother's false apology. This leads to a fight between Regina and Zelena but before this escalates, Cora restores their childhood memories of each other and she regretted the way she raised them, and apologizes to her daughters. Now that the sisters have made peace, Cora decides that it's time for her to move on from her unfinished business. As they see their mother walk toward the bridge, the flames from the River of Fire erupt and wrap around her. But the flames die down, the bridge forms, and the gate opens, allowing Cora to move on to Mount Olympus to join her husband, Prince Henry Mills. Later on, Regina gives Zelena her blessing to be with Hades, who is waiting for her at the Underworld Diner for their second date, which Zelena sees as an opportunity to reform him.
Andrea Towers of Entertainment Weekly gave it a positive review: "Ah, siblinghood. It's a complicated thing under the best of circumstances, but when motherly abandonment is at hand, well, the emotional impact is everlasting. Such is the case for sisters Regina and Zelena and twin brothers David and James, each of whom grew up in highly unequal circumstances and have been at odds with one another ever since," then later adds "While the sisters are ready to start over on newly feel-good footing, not every sibling reunion is a happy one tonight."
Abusive Parent: We see Zelena's father being physically and emotionally abusive to Zelena because he does not approve of her magic, just in time for a sympathetic episode about a slightly less abusive parent, Cora.
Acting for Two: Josh Dallas as both David and James.
Arc Words: A young Regina says "I will find you" to her sister as they're being torn apart in a flashback.
As You Know: A one-sided version. Cora tells Regina how the River of Forgetfulness works; Regina responds by saying she's already dabbled in memory-wiping potions before.
Bait-and-Switch: As she crosses the bridge, Cora is briefly covered with flames, indicating she'll still be eternally punished for her sins. But they fade as she is able to walk into the light.
We're briefly led to think the flashback will be about Regina bringing her doll to life.
Borrowed Catchphrase: Pan introduces himself to Zelena with a play on her own catchphrase, "The Queen may be evil, but I'm wicked", saying: Pan: "I hear you're wicked. Well, I'm much worse."
The Bus Came Back: Pan and Cora reappear in this episode, although the former does not show up until the end.
Call-Forward: The young Zelena and Regina play at attacking each other, unaware they'll be doing it for real decades later.
Continuity Nod: Hook smuggles his hook to Cora to use to cut her magical binding.
The young Zelena and Regina figure out they're sisters when Zelena opens a safe that can only be opened by blood magic.
Cruella punches Emma in the face and says "that's for killing me."
When Cruella goes for a gun, Hook points out that she can't kill anyone personally.
Cora mentions how she used to believe love was weakness, her Catchphrase.
We see that as a young kid, Regina never cared much about power and wealth even though she was raised by a strict mother, much like how Regina was before succumbing to dark magic.
Couch Gag: The title card features a windmill.
Does This Remind You of Anything?: Young Regina gets Cora's wand out of its safe spot and accidentally harms herself playing with it. Henry Sr. snaps at Cora about "not locking that thing up" to keep it safe from their child.
Even Evil Has Standards: Even Cora can't believe Hades could possibly change due to love and wants to save Zelena from him.
Evil Twin: James.
Eviler than Thou: Pan introduces himself to Zelena with a play on her own catchphrase, saying "I hear you're wicked. Well, I'm much worse."
Failed a Spot Check: Emma doesn't find it odd that "David" doesn't recognize when a photo of himself and Snow was taken, shrugging it off as "all the curses and time jumps" affecting his memory.
Foreshadowing: In the sneak peek, we see the interactions of two sets of siblings: Zelena and Regina, and David and James. However, the title is only "Sisters" instead of "Siblings", which foreshadows James' fate.
Forgotten First Meeting: Regina and Zelena as children, thanks to Cora.
Godzilla Threshold: Gold is so desperate to ensure the safety of Belle and their child that he's willing to team up with his father.
Heel Realization: After so long justifying her actions as helping Regina be a strong woman, Cora finally acknowledges that she did this for her own selfish desires and lust for power and how it ruined her daughters' lives and is sorry for it.
Hostage Situation: Aside from threatening Robin Hood at gunpoint until he hands over the baby, the reason James and Cruella want the baby is itself to engineer this: threatening the child of the woman Hades loves in order to get him to help them leave the Underworld and come back to life.
Idiot Ball: David lampshades how stupid it was for James to try and lock him up in a replica of his own jail.
It's All About Me: James completely blames David for "stealing my glory," ignoring how David had no idea James even existed and it's not his fault James got killed by accident.
Laser-Guided Amnesia: Water from the Lethe River does this. Cora used some once to make Regina and Zelena forget each other as children, and tries to use it again to make Zelena forget Hades, but Zelena figures out the ruse before she can.
Love Redeems: Zelena thinks she can do this to Hades, much to Cora and Regina's chagrin.
Seeing Regina and Zelena about to kill each other, Cora reveals to them how they had been true sisters long ago, admitting she'd been a fool for thinking love was a weakness. She apologizes to both for all the horrible treatment she gave them for her own selfish pursuits to finally earn their forgiveness. This turns out to be the unfinished business she needs to move on.
Motive Misidentification: The talk with Cruella made David believe James was upset because their mother kept David and gave James away. James instead reveals he's outraged that he got killed early and "the shepherd" got to enjoy a life of fame and riches.
Mythology Gag: When meeting Cora, the young Zelena starts to ask, "Are you a good witch or..."
Nice Job Breaking It, Hero: Zelena convincing Belle to curse herself drove Gold to agree to enter a deal with Pan that gets Zelena kidnapped.
No-Sell: Robin puts an arrow right in James' chest but he dryly points out he's already dead so it doesn't do any good.
Oh, Crap!: Zelena, upon meeting Pan.
Retcon: It's revealed that Regina and Zelena did meet as children, becoming friends and then learning they were sisters but Cora used a magic river's waters to erase their memories of the incident so their bond wouldn't interfere with her plans. Cora reveals this at last to the girls to finally break this cycle of hate.
Revenge Before Reason: Cruella urges "Jimmy" to leave the fight with David but he charges with a knife and ends up being knocked into the Lake of Souls.
Twin Switch: James impersonates David as part of his plans.
Villain Ball: If Gold hadn't decided to be the worst again and interfered in Zelena's romantic rendezvous with Hades, she might have been able to convince him to undo all his recent evil, which would include tearing up Gold's contract.
Villain Team-Up: Rumple is so desperate, he's willing to work with Pan.
Would Hurt a Child: The Woodcutter attempted to punish Zelena for using magic to stack firewood by beating her, only to be stopped by Cora. His wife had to protect Zelena from him before she died.