Chapter 3
Section 3.0
3.1But when Abel fell down upon the ground, seeing that his brother meant to kill him, he said to Cain, “O, my brother, have pity on me. By the breasts we have sucked, smite me not! By the womb that bare us and that brought us into the world, smite me not unto death with that staff! If you will kill me, take one of these large stones, and kill me outright.” Then Cain, the hard-hearted and cruel murderer, took a large stone and smote his brother with it upon the head, until his brains oozed out, and he weltered in his blood, before him. And Cain repented not of what he had done.
“O, my brother, have pity on me” and “If you will kill me, take one of these large stones, and kill me outright” corresponds to Lily begging Voldemort to "have mercy, have mercy" and "kill me instead".
The "large stone" in this passage is very significant - it's represented by the Resurrection Stone placed in the Gaunt ring.
Harry noticed a ring on his uninjured hand that he had never seen Dumbledore wear before: It was large, rather clumsily made of what looked like gold, and was set with a heavy black stone that had cracked down the middle. Slughorn’s eyes lingered for a moment on the ring too, and Harry saw a tiny frown momentarily crease his wide forehead. (HBP)
Sitting on one of the little spindle-legged tables that supported so many frail-looking silver instruments, was an ugly gold ring set with a large, cracked, black stone. (HBP)
Other than 'took a large stone and smote his brother with it upon the head" being an obvious reference to the lightning scar on Harry's forehead, it's also heavily tied to specifically brother-sister violence: Marvolo wears this ring - who presumably murdered his sister (Merope and Morfin's mother), and wore the ring while he strangled Merope. It's then passed down to Morfin - who attempted to kill his sister, and worn when he nearly kills Tom Riddle. Dumbledore meets his death due to a curse on that ring - who killed his sister Ariana, and the Resurrection Stone is tied to Dumbledore wishing to see Ariana again. The ring is finally passed down from Morfin to Tom Riddle - who killed his symbolic "sister" Lily.
The link between the Stone and Voldemort and Lily as "brother and sister" is demonstrated in HBP - Slughorn notices the ring, then soon begins describing Lily - who he describes exactly like Tom Riddle in Slughorn's memory where Tom is wearing that ring, drawing a significant parallel between them (see also: this post), which threads to Harry ultimately using Lily's murder ("You don't want to get rid of the wizard who killed Lily Evans?") to get the real memory.
It’s difficult to spot all the specific allusions to “the cruel and hard hearted murderer” since words like "cruel" and "heart" are used very often, but the most important one is likely the phrases used in the Godric's Hollow graveyard, the pivotal scene of the Cain and Abel narrative thread, where Harry goes with his “sister” Hermione, wearing Merope’s locket which symbolizes a sister’s murder by her brother Morfin, where the grave of the sister Dumbledore killed lies, and finally where Voldemort arrives and has a flashback to killing his “sister” Lily:
“Where your treasure is, there will your heart be also” on Ariana's grave, also echoing the words engraved on the Mirror of Erised - I show not your face but your heart's desire
Also important is that the locket horcrux is repeatedly described as a heart, particularly right before Voldemort appears in Godric's Hollow and has the flashback to Lily's murder, and then the locket leaves a mark on Harry's heart right after he sees the full memory of Lily's death, echoing the Mark of Cain and representing Harry feeling like Cain via guilt about Lily dying for him:
Was it his own blood pulsing through his veins that he could feel, or was it something beating inside the locket, like a tiny metal heart? (DH)
A metal heart was banging outside his chest, and now he was flying, flying (DH)
“I couldn’t get the Horcrux off you,” Hermione said […] “It was stuck, stuck to your chest. You’ve got a mark; I’m sorry, I had to use a Severing Charm to get it away. The snake bit you too, but I’ve cleaned the wound and put some dittany on it. . . .”
He pulled the sweaty T-shirt he was wearing away from himself and looked down. There was a scarlet oval over his heart where the locket had burned him. (DH)
As for Cain weltering in Abel's blood, the idea of a brother shedding a sibling's blood is alluded to in several instances - Peter as Cain taking Harry's blood in GoF and Voldemort as Cain using Harry's blood/Lily’s sacrifice to rebuild his body, and similarly the words about Voldemort’s murder of Lily in OoTP; Morfin's bloody knife in the Gaunt shack with the implication that Morfin as Cain was violent to Merope with that knife; and Dumbledore and Harry as Cain in the Cave (see section 3.3)
“I wanted Harry Potter’s blood. I wanted the blood of the one who had stripped me of power thirteen years ago... for the lingering protection his mother once gave him would then reside in my veins too...” (GoF)
“While you can still call home the place where your mother’s blood dwells, there you cannot be touched or harmed by Voldemort. He shed her blood, but it lives on in you and her sister. Her blood became your refuge” (OoTP)
he [Morfin] was brandishing a wand in one hand and a short and rather bloody knife in the other.
[...] With a roar of rage, Morfin leapt out of his chair and ran at Ogden, brandishing his bloody knife and firing hexes indiscriminately from his wand.
Ogden ran for his life. Dumbledore indicated that they ought to follow and Harry obeyed, Merope’s screams echoing in his ears.
“Where’s the locket, eh, where’s Slytherin’s locket?”
Voldemort did not answer. Morfin was working himself into a rage again; he brandished his knife and shouted, “Dishonored us, she did, that little slut! (HBP)
The words "until his brains oozed out" inspired the scene in the DoM with the brains that strangle Ron, Ron who starts to perform the part of Voldemort, this representing the memory of Lily's death strangling Voldemort:
“Honest, Harry, they’re brains — look — Accio Brain!”
[...] Harry, Ginny, and Neville and each of the Death Eaters turned in spite of themselves to watch the top of the tank as a brain burst from the green liquid like a leaping fish. For a moment it seemed suspended in midair, then it soared toward Ron, spinning as it came, and what looked like ribbons of moving images flew from it, unraveling like rolls of film —
“Ha ha ha, Harry, look at it —” said Ron, watching it disgorge its gaudy innards. “Harry, come and touch it, bet it’s weird —”
“RON, NO!”
Harry did not know what would happen if Ron touched the tentacles of thought now flying behind the brain, but he was sure it would not be anything good. (OoTP)
(A meta on how the DoM sequence is a step-by-step reenactment of the events between Voldemort, Lily, and Harry, much like the Slytherin locket cave is a step-by-step reenactment of the Life and Death of Merope Gaunt, coming at some point.)
3.2According to the Book of Jubilees, Cain murdered his brother with a stone. Afterwards, Cain was killed by the same instrument he used against his brother; his house fell on him and he was killed by its stones. A heavenly law was cited after the narrative of Cain's death saying:
With the instrument with which a man kills his neighbour with the same shall he be killed; after the manner that he wounded him, in like manner shall they deal with him.
This one’s particularly interesting and could have many meanings. The most basic reference is likely Cain's house falling down on him linking to the roof of the Godric's Hollow house being blasted apart:
Most of the cottage was still standing […] but the right side of the top floor had been blown apart; that, Harry was sure, was where the curse had backfired. He and Hermione stood at the gate, gazing up at the wreck of what must once have been a cottage just like those that flanked it.
“I wonder why nobody’s ever rebuilt it?” whispered Hermione.
“Maybe you can’t rebuild it?” Harry replied. “Maybe it’s like the injuries from Dark Magic and you can’t repair the damage?” (DH)
And then he broke: He was nothing, nothing but pain and terror, and he must hide himself, not here in the rubble of the ruined house, where the child was trapped and screaming, but far away... far away... (DH)
But more interesting is the cyclical violence this passage links to - it was Dumbledore’s obsession with the Deathly Hallows that led to neglect of Ariana and in a way her death, and Dumbledore is then killed by that same obsession, with the Resurrection Stone, fatally cursed by the horcrux that is symbolically linked to Ariana's murder:
“And at the heart of our schemes, the Deathly Hallows! How they fascinated him, how they fascinated both of us! The unbeatable wand, the weapon that would lead us to power! The Resurrection Stone -- [...] To me, I confess, it meant the return of my parents, and the lifting of all responsibility from my shoulders.” (DH)
After another short pause Harry said, “You tried to use the Resurrection Stone.”
Dumbledore nodded.
“When I discovered it, after all those years, buried in the abandoned home of the Gaunts — the Hallow I had craved most of all, though in my youth I had wanted it for very different reasons — I lost my head, Harry. I quite forgot that it was now a Horcrux, that the ring was sure to carry a curse. I picked it up, and I put it on, and for a second I imagined that I was about to see Ariana, and my mother, and my father, and to tell them how very, very sorry I was..." (DH)
Dumbledore is then weakened further by Merope's locket, which is also linked to Merope's murder by her brother and during which Dumbledore sees himself kill Ariana, repeatedly alluding to brother-sister violence.
Something else notable is that Dumbledore doesn’t die immediately - his death is drawn out, suffering under the Gaunt ring curse for a year. This parallels how Voldemort’s death is drawn out after murdering his "sister" and trying to murder his "brother" Harry, spending 13 years in Albania and then a few chasing after Harry.
Other than the obvious of the rebounding Killing Curse, you could say it was similarly Voldemort’s obsession with a Deathly Hallow - the Elder Wand - that killed his “brother” Snape, and Voldemort is then defeated by the Elder Wand.
It could also apply to the Resurrection Stone with regards to Voldemort and Lily, Voldemort symbolically killing Lily with the "large stone", and in one interpretation being defeated by the Resurrection Stone/the Deathly Hallows if you accept that was why Harry survived.
Interestingly 1) Harry has a dream with Nagini (Voldemort's symbolic mother) going through the Gaunt ring with the Resurrection Stone and then Lily's grave - in the same chapter the Silver Doe appears, and only a chapter after he visits Lily's grave and sees the memory of her murder 2) The Lily from the Resurrection Stone parallels Morfin while he's wearing the Gaunt ring with the Stone in it - both of these again hinting at a brother killing a sister with the "large stone" in the Cain and Abel retelling:
Harry’s dreams were confused and disturbing: Nagini wove in and out of them, first through a gigantic, cracked ring, then through a wreath of Christmas roses. (DH)
Lily’s smile was widest of all. She pushed her long hair back as she drew close to him, and her green eyes, so like his, searched his face hungrily, as though she would never be able to look at him enough. (DH)
Morfin pushed the hair out of his dirty face, the better to see Riddle, and Harry saw that he wore Marvolo’s black-stoned ring on his right hand. (HBP)
This ultimately threads to it being Lily's soul that came out of the Resurrection Stone and created the versions of James, Sirius, and Remus, the way the locket creates Riddle-Harry and Riddle-Hermione (more on this in future metas).
3.3However, there is a cave, called the "Blood Cave", in a mountain located to the northern part of Syria. It is thought to be the scene of the crime where Cain killed his brother Abel. […] Ahmed came to know from Abel -who took an oath of that- it was his own blood (that was spilt there (in that very cave)). Abel said that he had asked Allah Almighty to make the invocations and supplications offered in that place acceptable […] However, it is to be stated that this narration represents only a vision.
The Blood Cave corresponds to Slytherin locket cave, which is constructed by Voldemort as a symbolic representation of the Gaunt shack - hence being the scene of the crime where Cain killed Abel; it represents the house in which Merope was murdered by her brother (see my meta Slytherin Locket Cave: The Life and Death of Merope Gaunt), and fitting the thread of sisters murdered by brothers, Dumbledore drinks the Emerald potion in that cave and sees himself killing Ariana:
“I rather think,” said Dumbledore, putting his uninjured hand inside his robes and drawing out a short silver knife of the kind Harry used to chop potion ingredients, “that we are required to make payment to pass.”
“Payment?” said Harry. “You’ve got to give the door something?”
“Yes,” said Dumbledore. “Blood, if I am not much mistaken.”
“Blood?”
[...] There was a flash of silver, and a spurt of scarlet; the rock face was peppered with dark, glistening drops.
“You are very kind, Harry,” said Dumbledore, now passing the tip of his wand over the deep cut he had made in his own arm, so that it healed instantly [...] “But your blood is worth more than mine. Ah, that seems to have done the trick, doesn’t it?”
The blazing silver outline of an arch had appeared in the wall once more, and this time it did not fade away: The blood-spattered rock within it simply vanished, leaving an opening [...] (HBP)
“The archway will have sealed again... My knife...”
“There’s no need, I got cut on the rock,” said Harry firmly. “Just tell me where...”
“Here...”
Harry wiped his grazed forearm upon the stone: Having received its tribute of blood, the archway reopened instantly. (HBP)
This is another interesting detail in the Cave scene:
Harry saw his face reflected, upside down, in the smooth surface of the green potion.
Harry hesitated, looking into the blue eyes that had turned green in the reflected light of the basin. (HBP)
Dumbledore and Harry both have their blood spilled by the “blood ward” that echoes Lily’s blood ward resulting from her murder by her “brothers; Dumbledore and Harry both also reflect the Emerald Potion symbolizing Merope’s murder by her family - a.k.a. they’re both reflecting Voldemort as Cain who regularly kills his family. This again alludes to Harry's helplessness and feeling like Cain regarding Lily's death (and Sirius, and marked to be a brother-killer due to being prophesied to kill his “brother” Voldemort, etc etc), and Dumbledore’s same feeling about Ariana.
But Dumbledore's eyes reflecting green also refers to him reflecting Lily, as Dumbledore's words while drinking the potion echoes Lily's last words:
“Don’t hurt them, don’t hurt them, please, please, it’s my fault, hurt me instead... ”
[...] “Please, please, please, no... not that, not that, I’ll do anything...”
[...] Dumbledore drank, and no sooner had he finished than he yelled, “KILL ME!” (HBP)
“Not Harry, not Harry, please not Harry!”
[...] “Not Harry, please no, take me, kill me instead —”
[...] “Not Harry! Please... have mercy... have mercy... Not Harry! Not Harry! Please — I’ll do anything —” (DH)
The significance of this is double-edged, again emphasizing both of them as Cain; Dumbledore's words are about him killing his sister Ariana, and Lily's last words are the verbal agreement that kills her "brother" Voldemort.
3.4 Significantly the Quran, in which Cain and Abel are called Qabil and Habil, is the text in which Cain shows remorse for killing Abel in one interpretation, hence why Voldemort is given a chance for remorse (there's different wording used in different translations - one uses "remorse", another "regret" and JKR incorporated both into the text).
Allah Almighty says: {Then, Allah sent a crow who scratched the ground to show him how to hide the dead body of his brother. He (the murderer) said: "Woe to me! Am I not even able to be as this crow and to hide the dead body of my brother? "Then he became one of those who regretted} // Then he became full of remorse at his doing.
Some interpreters said: "After Cain had killed his brother, he carried him on his back for a full year (not knowing what to do with his brother's corpse!)." Others said: He carried him on his back for one hundred years till Allah Almighty sent two crows who fought against one another. One of them was killed. The murderer scratched the ground to hide the body of the dead crow. Seeing him doing that, Cain said: Woe to me! Am I not even able to do as this crow and to hide the dead body of my brother? Then, he buried the body of his dead brother and covered it with earth.
Not sure what the crows refers to - maybe the phoenix cores fighting against one another. Cain carrying Abel's dead body on his back may refer to the horcrux inside Harry, or Harry's blood and Lily's protection inside Voldemort.
And with a few exceptions, whenever the word remorse comes up, it isn’t about remorse for a character’s crimes in general, it’s an (often indirect) allusion to remorse about killing a sister or brother, tying it to the Cain and Abel thread.
I’ll now go through the relevant instances the word “remorse” appears and demonstrate this:
The man with the cold voice had killed a woman. He was talking about it without any kind of remorse — with amusement. He was dangerous — a madman. And he was planning more murders — this boy, Harry Potter, whoever he was — was in danger — (GoF)
After a minute or so, he looked down at Harry again, a cruel smile twisting his snakelike face.
“You stand, Harry Potter, upon the remains of my late father,” he hissed softly. “A Muggle and a fool... very like your dear mother. But they both had their uses, did they not? Your mother died to defend you as a child... and I killed my father, and see how useful he has proved himself, in death...”
Voldemort laughed again. (GoF)
While the first quote refers to Bertha Jorkins, it's meant to evoke Lily's murder (JKR does this often - i.e. sometimes there will be phrases like "a woman screamed" and it'll be about someone else but is also meant to be an allusion to Lily). Voldemort similarly talks about Lily’s murder with amusement, and he also refers to Bertha as “useful” 4 times, just like how he refers to Lily.
Voldemort had "killed a woman" evoking Lily a.k.a. Cain killing Abel, the first murder on Earth and Cain as the first murderer, and was "planning more murders", that after killing his "sister" Lily with no remorse he planned to kill his "brother" Harry.
“This discussion is getting us nowhere,” said Ogden firmly. “It is clear from your son’s attitude that he feels no remorse for his actions.” (HBP)
The above quote is about Morfin’s actions of attacking Riddle Sr, which Morfin did specifically in retaliation for Merope’s attraction to him - and then, while bragging, Morfin uses that to sell out Merope to Marvolo, leading Marvolo to nearly kill her. Thereby the true meaning of this is about Morfin feeling no remorse for trying to kill his sister.
Right after the quote about Morfin, Voldemort is referred to as remorseless:
“No, I did not. Though he had shown no hint of remorse, it was possible that he felt sorry for how he had behaved before and was resolved to turn over a fresh leaf. I chose to give him that chance.” (HBP)
This echoes the quote about Bertha Jorkins - similar to that, while Dumbledore is literally describing Tom's actions at the orphanage, this also evokes the idea that Voldemort had a choice after killing his sister Lily, the "first" murder - to turn over a fresh leaf and not to commit more murders of his "family", not to kill his “brother” Harry too, but he doesn’t take the chance and continues to go after him.
“Yeah… Voldemort murdered him and then stepped over his body toward my mum,” said Harry.
Slughorn gave a great shudder, but he did not seem able to tear his horrified gaze away from Harry’s face.
“He told her to get out of the way,” said Harry remorselessly. “He told me she needn’t have died. He only wanted me. She could have run.” (HBP)
Notice how above it specifically says “remorselessly” when Harry starts describing the moments of Lily’s death - alluding to Voldemort being remorseless and repenting not of what he’d done in killing his “sister” Lily.
“You have no idea of the remorse Professor Snape felt when he realized how Lord Voldemort had interpreted the prophecy, Harry. I believe it to be the greatest regret of his life and the reason that he returned —” (HBP)
The word remorse is used for Snape thrice, always referring to his murder of his "sister" Lily, and the "greatest regret of his life" echoes "Then he [Cain] became one of those who regretted".
In the following quotes, notice the phrasing and how it echoes Voldemort’s destruction by the Killing Curse rebounding, and how "Remorse. You've got to really feel what you've done" echoes "Cain repented not of what he had done".
“Remorse,” said Hermione. “You’ve got to really feel what you’ve done [...] Apparently the pain of it can destroy you. I can’t see Voldemort attempting it somehow, can you?” (DH)
“My curse was deflected by the woman’s foolish sacrifice, and it rebounded upon myself. Aaah... pain beyond pain, my friends; nothing could have prepared me for it. I was ripped from my body, I was less than spirit, less than the meanest ghost” (GoF)
here, within sight of that house where he had come so close to knowing what it was to die… to die... The pain was so terrible… ripped from his body… (DH)
The word remorseless is again used in relation to Lily’s sacrificial protection and blood wards, resulting from her “brother” Voldemort’s murder of her, again tying it to Cain and Abel:
“— Kingsley and Mr. Weasley explained it all as well,” Harry pressed on remorselessly. “Once I’m seventeen, the protective charm that keeps me safe will break, and that exposes you as well as me.” (DH)
Then Harry feels remorse in relation to Molly, his mother figure who's a replacement for Lily:
She looked at him, a long, searching look, then smiled a little sadly, straightened up, and walked away. Harry watched as she waved her wand near the washing line, and the damp clothes rose into the air to hang themselves up, and suddenly he felt a great wave of remorse for the inconvenience and the pain he was giving her. (DH)
Molly's sad smile here evokes Lily "crying but smiling" at Harry from the Mirror of Erised (as well as Lily giving a "sad little smile" to Snape in The Prince's Tale).
Ron responded by maintaining an unnaturally somber demeanor in her presence as an outward sign of continuing remorse. (DH)
The above is Ron's remorse for hurting his "sister" Hermione, and he echoes Cain here because in the locket scene and in his jealous and hot-tempered demeanor he reflected Voldemort as Cain (see section 2.3 in Part 1)
“I regret it,” said Voldemort coldly.
He turned away; there was no sadness in him, no remorse. (DH)
The above refers to Voldemort’s lack of remorse for killing his “brother” Snape.
“I picked it up, and I put it on, and for a second I imagined that I was about to see Ariana, and my mother, and my father, and to tell them how very, very sorry I was...”
“He ran, while I was left to bury my sister, and learn to live with my guilt and my terrible grief, the price of my shame.” (DH)
“They say he showed remorse in later years, alone in his cell at Nurmengard. I hope that it is true. I would like to think he did feel the horror and shame of what he had done. Perhaps that lie to Voldemort was his attempt to make amends... to prevent Voldemort from taking the Hallow...” (DH)
Notice the phrasing here - the "horror and shame" Grindelwald felt echoes the "price of Dumbledore's shame" that's specifically about Ariana's murder, and how "feel the horror and shame of what he had done" echoes "Cain repented not of what he had done" - linking the remorse Grindelwald feels to Ariana's death, his "sister"/"sister-in-law's" death (a brother-in-law's violence to a sister-in-law is additionally explored in DH via Lucius Malfoy putting his hands on Bellatrix).
Interestingly, the Gray Lady's story about the Bloody Baron also echoes that of Cain and Abel:
“The Bloody Baron, yes,” said the Gray Lady, and she lifted aside the cloak she wore to reveal a single dark wound in her white chest. “When he saw what he had done, he was overcome with remorse. He took the weapon that had claimed my life, and used it to kill himself. All these centuries later, he wears his chains as an act of penitence… as he should,” she added bitterly. (DH)
The Baron feels remorse for killing the Gray Lady, and kills himself with the same weapon that claimed her life, just like Cain is killed by the instrument that claimed Abel's life. Additionally "When he saw what he had done, he was overcome with remorse" echoes "Cain repented not of what he had done".
The Gray Lady has many, many ties to Lily - her and the Baron represent Lily and Snape but also represent Lily and Voldemort (alluding to the thread of Cain wanting to marry his twin sister - see below), but I'll save that for another meta.
3.5 As mentioned before, in many versions, Cain and Abel have twin sisters, and the interpretations surrounding the twin sisters vary as well. In some interpretations, Cain and Abel each have one twin sister. In others, Abel has two twin sisters and Cain one. Still in others, Abel has two sisters and Cain none. Etc.
And instead of whose sacrifice was favored by God causing the murder, Cain killing Abel is caused by them fighting over which one of them would marry their sister(s).
[...] Adam used to get the male brought by one birth married to the female brought by the other. Hence, it was supposed that Abel would get married to Cain's sister who was better and more beautiful than anyone else. At the same time, Cain wanted to keep her for himself. Adam ordered him to allow Abel to marry her, but he totally refused. [...] Later, a fire came down from heaven and consumed the sacrifice offered by Abel and left untouched that of Cain. Cain became livid with rage and said to his brother: I will kill you so as not to marry my sister
In one interpretation you could read Lily as Voldemort's twin sister and Hermione as Harry's, or else in another reading Lily and Hermione are both Harry's twin sisters, in another they’re both Voldemort’s, etc. (Something to note is that Harry and Hermione fit the twin/sibling naming patterns - i.e. Parvati and Padma, Albus Aberforth and Ariana, Amycus and Alecto, Rodolphus and Rabastan, etc.)
Locket Riddle creates a version of Harry as Cain who wants to marry his twin sister Hermione - Riddle-Harry and Riddle-Hermione stand side by side in the mirrors of the locket like husband and wife James and Lily stand next to each other in the Mirror of Erised; they’re like trees with a common root aka on the same family tree aka cousins/“brother and sister”; they’re described as having the same hair, the same eyes, the same voice - they look exactly alike, like twins, like family.
But of course, the real Harry rejects this version:
the figures blossomed out of the locket, first chests, then waists, then legs, until they stood in the locket, side by side like trees with a common root
“Who wouldn’t prefer him, what woman would take you, you are nothing, nothing, nothing to him,” crooned Riddle-Hermione, and she stretched like a snake and entwined herself around Riddle-Harry, wrapping him in a close embrace: Their lips met.
“She’s like my sister,” he went on. “I love her like a sister and I reckon she feels the same way about me. It’s always been like that. I thought you knew.” (DH)
And then notice how the wording in the following quote echoes the Cain and Abel passage - that “it was supposed that Abel would get married to Cain's sister who was better and more beautiful than anyone else”
“Presumption!” echoed the Riddle-Hermione, who was more beautiful and yet more terrible than the real Hermione (DH)
(This thread surrounding Hermione as the twin sister is also referred to in the Godric's Hollow graveyard scene, which I'll get into in future metas) Everything in this scene ties back to this being Merope’s locket - who also would’ve had to marry her brother, and presumably traditionally that locket's two windows would've contained portraits of Morfin and Merope.
As for Voldemort himself, he has several symbolic marriages with his "twins". The thread of Cain wanting to marry his twin sister exists with Voldemort and Lily too (highly symbolically), and with Voldemort and Ginny, which I’ll elaborate on that in other metas.
There's Snape and Voldemort as a symbolic marriage emphasized by Ravenclaw's diadem associated with Snape and likened to Fleur's wedding tiara:
He strode right up to the marble woman, and she seemed to look back at him with a quizzical half smile on her face, beautiful yet slightly intimidating. A delicate-looking circlet had been reproduced in marble on top of her head. It was not unlike the tiara Fleur had worn at her wedding. (DH)
There it was, right ahead, the blistered old cupboard in which he had hidden his old Potions book, and on top of it, the pockmarked stone warlock wearing a dusty old wig and what looked like an ancient, discolored tiara. (DH)
The description "pockmarked warlock" with the "dusty wig" also evokes Snape's appearance, who isn't specifically described as pockmarked, but Elphias Doge is in DH - Doge parallels Snape in having a "pockmarked visage and greenish hue", like Snape's greasy curtains of hair and sallow greasy skin, and Doge's friendship with Dumbledore of two outsiders reflects Snape and Lily's friendship.
Snape is also connected to the diadam via this passage, while Voldemort's agonizing over losing Hufflepuff's cup, which Voldemort entrusted to Bellatrix, his symbolic "wife":
To tell Snape why the boy might return would be foolish, of course; it had been a grave mistake to trust Bellatrix and Malfoy: Didn’t their stupidity and carelessness prove how unwise it was ever to trust? (DH)
Voldemort of course doesn't tell Snape the truth about the diadem, but the wording here suggests that under other circumstances he might've trusted Snape enough and told him it was a horcrux, and it was his feelings of betrayal and fear of vulnerability after the Cup's loss that kept him from doing so.
The diadem is further linked female figures in the passage where it's destroyed:
all around them the last few objects unburned by the devouring flames were flung into the air, as the creatures of the cursed fire cast them high in celebration: cups and shields, a sparkling necklace, and an old, discolored tiara — (DH)
The cups evoke Hepzibah Smith's/Helga Hufflepuff's cup, the shields refer to Lily (see my meta "When Lily Cast Her Life As A Shield": Analysis of the Shield Charm), the necklace an obvious reference to Merope's locket, and then Rowena and Helena Ravenclaw's diadem.
Voldemort's symbolic marriage with Harry is implied in the Dracula allusions that you can read about in this post.
3.6Now there were born with Abel two daughters, his sisters. Then said Cain, 'I will take the one I choose, I am the eldest;' Abel said, 'They were born with me, and I will have them both to wife.' And when they fought, Abel flung Cain down and was above him; and he lay on Cain. Then Cain said to Abel, 'Are we not both sons of one father; why wilt thou kill me?' And Abel had compassion, and let Cain get up. And so Cain fell on him and killed him. From this we learn not to render good to the evil, for, because Abel showed mercy to Cain, Cain took advantage of it to slay Abel.
The following corresponds to the sentence “And when they fought, Abel flung Cain down and was above him; and he lay on Cain”:
The stairs were steep and narrow: Harry was half tempted to place his hands on stout Bathilda’s backside to ensure that she did not topple over backward on top of him, which seemed only too likely.
He could not get enough breath into his lungs to call back: Thena heavy smooth mass smashed him to the floor and he felt it slide over him, powerful, muscular —
“No!” he gasped, pinned to the floor. (DH)
“It is over! Set him down, Hagrid, at my feet, where he belongs!”
Harry felt himself lowered onto the grass.
“You see?” said Voldemort, and Harry felt him striding backward and forward right beside the place where he lay. (DH)
And the below quotes is Harry as Abel showing compassion to Voldemort as Cain - and right after Harry shows him mercy, Voldemort tries to kill him:
Small and fragile and wounded though it was, he did not want to approach it. Nevertheless he drew slowly nearer, ready to jump back at any moment. Soon he stood near enough to touch it, yet he could not bring himself to do it. He felt like a coward. He ought to comfort it, but it repulsed him.
“You cannot help.”
He was distracted by the whimpering and thumping of the agonized creature behind them and glanced back at it yet again.
“Are you sure we can’t do anything?”
“There is no help possible.” (DH)
“But before you try to kill me, I’d advise you to think about what you’ve done... Think, and try for some remorse, Riddle...”
[...] “It’s your one last chance,” said Harry, “it’s all you’ve got left... I’ve seen what you’ll be otherwise... Be a man... try... Try for some remorse...” (DH)
Notice how the wording echoes Dumbledore’s - Lily’s sacrifice is Voldemort’s “one last hope for himself” and remorse is his “one last chance”, plus “Think about what you’ve done” echoes “Cain repented not of what he had done”.
Interestingly, Harry’s words here mirror Voldemort’s words to him in the graveyard in GoF, during which Voldemort’s words echo what Frank Bryce says to him:
“Is that right?” said Frank roughly. “Lord, is it? Well, I don’t think much of your manners, my Lord. Turn ’round and face me like a man, why don’t you?”
“But I am not a man, Muggle,” said the cold voice, barely audible now over the crackling of the flames. “I am much, much more than a man. However... why not? I will face you... Wormtail, come turn my chair around.” (GoF)
“And now you face me, like a man... straight-backed and proud, the way your father died...” (GoF)