Who Is R.A.B In Harry Potter? Regulus Black, Explained

Throughout the “Harry Potter” books and movies — the original ones, not the “Fantastic Beasts” franchise — there are plenty of mysteries scattered around for both the audience and Harry (Daniel Radcliffe) himself to solve. In fact, if you take each installment one by one, they’re basically all mystery books. Who’s after the titular Stone in “Harry Potter and the Sorcerer’s Stone?” Who is the real Heir of Slytherin in “Harry Potter and the Chamber of Secrets?” Why is alleged murderer Sirius Black (Gary Oldman) hellbent on finding Harry at Hogwarts School of Witchcraft and Wizardry in “Harry Potter and the Prisoner of Azkaban?” Who put Harry’s name in the Goblet of Fire in, well, “Harry Potter and the Goblet of Fire?” I don’t need to go on — you get it. You’re smart.

During the final books and films in “Harry Potter,” the mysteries start to point firmly in one direction: the solution that will take down the Dark Lord Voldemort (Ralph Fiennes) once and for all. As Harry and his mentor Albus Dumbledore (Michael Gambon) discover in “Harry Potter and the Half-Blood Prince,” Voldemort performed a truly horrific act seven times over, killing in order to split his soul and create Horcruxes, meaning that seven distinct pieces of his soul reside within enchanted objects (or, in two cases, living beings) and prevent him from being killed outright. In order to definitively kill Voldemort, Harry and his friends Ron Weasley (Rupert Grint) and Hermione Granger (Emma Watson) have to track down each Horcrux and figure out how to destroy them in the first place … which is where a locket belonging to a man initially known only as “R.A.B.” comes into play.

So, who is “R.A.B.?” Why is the locket important, and why are there actually two of them? I’ll explain. Here’s everything you need to know about R.A.B.’s locket in “Harry Potter” and the specific mysteries it unlocks.

Harry and Dumbledore spend the majority of “The Half-Blood Prince” simply learning that Voldemort has Horcruxes in the first place, but in the third act of both the book and the film, the two actually set out to find one of the objects. Based on memories purloined from people who knew Voldemort when he was simply a sinister orphan named Tom Riddle, Harry and Voldemort visit a remote cave in the side of a cliff where they believe a young Tom Riddle tortured other children from his orphanage; inside, they find a creepy black lake home to a single island that quite obviously holds the Horcrux.

The whole enterprise is sinister right from the jump — Dumbledore has to shed blood directly onto the rocks outside of the cave to even enter — and he notes that only a powerful wizard can control the small boat hidden within the lake, meant only for one wizard. (Harry, who isn’t “of age” yet, doesn’t “count” as a passenger, according to Dumbledore; the Hogwarts headmaster tells Harry that Voldemort would never have considered the possibility that an underage wizard could even reach the cave.) After the two reach the container holding the locket — crossing the lake filled with Inferi, which are magically reanimated dead bodies and guard the Horcrux — they realize someone has to drink the green liquid in the basin in order to remove it.

Dumbledore volunteers to drink it — even as Harry has to force the potion down a tortured Dumbledore’s throat — and though it severely weakens the elder wizard, the two manage to leave the cave with the locket. It’s only after Dumbledore’s death shortly thereafter (which happens back at Hogwarts) that Harry realizes the locket, which bears the initials “R.A.B.,” is empty; it’s a fake, and the real Horcrux is still out there.

So, who is R.A.B.? As Harry and his friends eventually learn, the locket belonged to Sirius’ brother Regulus Arcturus Black, who, keeping with the Black family tradition, valued pureblood lineage and proved his commitment to that particular cause by allying himself with Voldemort as one of the Dark Lord’s “Death Eaters.” In the fifth book, “Harry Potter and the Order of the Phoenix,” Sirius is showing Harry his family tree — magically placed upon a tapestry — when they come across Regulus’ name. When Harry asks what happened, Sirius bluntly says he died: “Stupid idiot … he joined the Death Eaters.”

We don’t hear about Regulus again until “Harry Potter and the Deathly Hallows” (the film adaptation of the book is split into two parts, and this occurs in “Part 1”), when Harry, Ron, and Hermione are using the Black family home at 12 Grimmauld Place as a hideaway and realize the initials probably have to refer to Sirius’ brother. When they enter his room, they find that a young Regulus tacked newspaper clippings onto the wall, and Hermione immediately notices something. “‘They’re all about Voldemort,’ [Hermione] said. ‘Regulus seems to have been a fan for a few years before he joined the Death Eaters …'”

By this point, Sirius is dead, so it seems like the trio have no way to learn any truths about Regulus. There is a way, though: Kreacher the house-elf, who technically “belongs” to Harry (as Sirius left the home to Harry in his will, and Kreacher comes with the house). Despite the fact that Kreacher is openly hostile towards Harry, Ron, and Hermione, they ask him to talk about Regulus, and from there, they learn more about the locket and how it got into Voldemort’s secret hiding spot.

Though he’s resistant at first, Kreacher ultimately opens up to Harry, Ron, and Hermione — and reveals a new side of Regulus. When Regulus first started working with Voldemort, he sent Kreacher with the Dark Lord to help him with an unknown task; that task was that Kreacher had to basically test-drive the defenses within the cave and drink the horrible potion, causing the house-elf unimaginable pain. (As the trio realizes during Kreacher’s story, Voldemort didn’t consider Kreacher to be a real being and didn’t hesitate before using the house-elf as a guinea pig.) Because Regulus ordered Kreacher to “come back” — house elves must obey their masters and employ extremely powerful magic in the process — Kreacher told Regulus everything that happened, leaving Regulus horrified.

As a result, Regulus decides to get revenge on Voldemort and go into the cave himself with Kreacher; this time, Regulus drinks the potion. The turncoat Death Eater then takes the real Horcrux, puts his monogrammed locket into the basin, and tells Kreacher that he must leave and destroy the real Horcrux … and as they try to leave, a weakened Regulus is dragged into the lake and killed by Inferi. Despite his orders, Kreacher can’t figure out how to even open the locket, much less destroy it — and though Kreacher hoarded the locket for years, it was ultimately purloined by the thief Mundungus Fletcher (Andy Linden), who has no idea what it really is, after Sirius’ death.

Mundungus is actually the reason that Harry, Ron, and Hermione learn about the locket from Kreacher in the first place; Harry gives Kreacher an order to track down whoever stole the locket, and Kreacher brings Mundungus himself to Grimmauld Place. There’s one huge problem: Mundungus doesn’t have the locket, but says a woman who works for the Ministry of Magic who “looks like a toad” confiscated it.

“Harry Potter” fans know precisely who Mundungus was describing, and Harry, Hermione, and Ron know too: Dolores Umbridge, played in the films by Imelda Staunton, is the one in possession of the locket. After a ton of planning, Ron, Hermione, and Harry leave Grimmauld Place and waylay three Ministry of Magic employees — Reginald Cattermole, Mafalda Hopkirk, and Albert Runcorn, respectively — before stealing hairs from each person and using Polyjuice Potion, entering the Ministry itself (despite the fact that Harry is the most wanted fugitive in the Wizarding World). Harry causes a diversion and searches Umbridge’s office, but the locket isn’t there; unfortunately, she’s wearing the thing as she holds trials in the bowels of the Ministry and interrogates Muggleborn witches and wizards about how they “stole” magic from legitimate pureblood wizards. (This is not a thing; Umbridge is just a bigot.)

Hermione, as Mafalda, is serving as Umbridge’s stenographer, and Mary Cattermole — the Muggleborn wife of the real Reginald Cattermole — is the one on trial in front of Umbridge, putting Ron and Hermione in sticky situations. Harry ultimately enters the courtroom as Runcorn and sees Umbridge wearing the locket; when the disguised Hermione inquires about it, Umbridge lies and says the “S” on the front represents the Selwyn family, an ancient pureblood line. (This is also not a thing, as Harry knows firsthand. The locket has an “S” on it for Salazar Slytherin, its original owner.) Furious, Harry stuns Umbridge and the trio help Mary escape before fleeing themselves. Tragically, because someone from the Ministry clings to Hermione’s robes as she Apparates to Grimmauld Place, that Ministry official can now enter the home, and they cannot return.

After infiltrating the Ministry, Harry, Ron, and Hermione go on the run, camping out in different remote places to try and hide from Voldemort and his followers. They take turns wearing the locket for safekeeping, but yet another problem arises: because the Horcrux has, for lack of a better term, bad vibes, anyone wearing it feels absolutely miserable, and Ron is by far the most affected. After wearing the Horcrux too much, Ron flies off the handle, accusing Harry of having “no plan” to find the Horcruxes, and he leaves — leaving both Harry and Hermione inconsolable.

Hermione and Harry get into some serious scrapes of their own — including a terrible experience in Godric’s Hollow, where Harry’s parents once lived — but one cold night, Harry wanders into the Forest of Dean after following a white light that resembles a Patronus Charm. The light leads Harry to a frozen lake, and he can clearly see that, somehow, the Sword of Gryffindor is at the bottom … and as Hermione deduced, the sword, imbued with basilisk venom from a battle in “Chamber of Secrets,” is powerful enough to actually take down a Horcrux. Harry recklessly dives in wearing the locket, which almost kills him in the water before he’s dragged out by Ron himself, who followed Harry into the woods after the two were apart for weeks.

Harry tells Ron to use the sword to destroy the locket, and even though the haunted piece of jewelry puts up a good fight — by psychologically torturing Ron and telling him that Hermione loves Harry, not Ron — Ron kills the soul residing inside with Gryffindor’s sword, and the gang reunite and set off to find the next Horcrux. Years after he entered Voldemort’s cave with Kreacher, Regulus made it possible for the Boy Who Lived to finally destroy the Horcrux once and for all.