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Who is R.A.B. in Harry Potter? The story behind the Horcrux mystery

Three initials were very important in the final Harry Potter movies and the hunt for Horcruxes, so let's delve into the secrets of R.A.B.

The mystery of R.A.B. in Harry Potter explained

There are dozens of mysteries littered throughout the Harry Potter series. Who is the Half-Blood Prince? Who opened the Chamber of Secrets? Why do the characters have so much hair in the Goblet of Fire movie? But one of the biggest conundrums was the identity of R.A.B. in Harry Potter. And those three initials were key to a crucial part of Voldemort’s fall at the end of the wizarding war.

The final two Harry Potter movies are built around the core trio of Harry Potter characters hunting for Horcruxes. That’s made harder by the fact that one of the few Horcruxes they know about is in the hands of a mysterious enemy of Voldemort known only as R.A.B. In order to find and destroy it, they had to figure out that person’s identity. Fortunately, you don’t have to solve the mystery because we’ve got all of the answers.

Who is R.A.B. in Harry Potter?

R.A.B. was the mysterious way Regulus Arcturus Black, Sirius’s brother, signed off the note he left for Voldemort when he stole Slytherin’s locket from the cave where it was hidden, before Harry and Dumbledore got there. 

Harry and Dumbledore pushed themselves to their limits in order to retrieve what they believed to be Salazar Slytherin’s locket. Voldemort had gone to great lengths to protect the locket, forcing anyone who found its cave to drink a potion that would weaken and torment them before facing an army of reanimated corpses, aka Inferi, in order to escape.

Harry Potter and Dumbledore struggled to get the locket, only for R.A.B. to get there first

So we can understand why Harry was furious to discover that the locket was a fake, containing a note signed off by R.A.B. He wrote that he had uncovered Voldemort’s secret and would destroy the locket as soon as he could.

In The Deathly Hallows, Harry and his friends worked out that R.A.B. could refer to Sirius Black‘s brother, Regulus. With the reluctant help of the house elf Kreacher, they learned that Regulus was indeed the person responsible.

Voldemort had callously used Kreacher to test his security, and the elf told Regulus everything. His master had then switched allegiances and decided he had to help in Voldemort’s downfall.

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How did Regulus Black get the Horcrux?

Regulus Black used the house elf Kreacher to assist him in reaching the center of the cave, then drank the horrific potion himself before allowing the army of Inferi to kill him so that Kreacher could escape with the locket.

Just as Voldemort had done, Regulus took Kreacher to accompany him into the center of the cave. However, Regulus refused to allow Kreacher to drink the potion again and consumed it himself. He ordered Kreacher to leave once the elf had retrieved the locket and replaced it with the fake.

Kreacher watched as his master was dragged underwater by the Inferi and was grief-stricken when he realized that he could not destroy the locket. Eventually, Mundungus Fletcher stole the locket from 12 Grimmauld Place and sold it to Dolores Umbridge. Naturally, any artifact related to Slytherin was of great interest to Harry Potter villains.

This story was largely cut out of the first Deathly Hallows movie in order to streamline the plot, but in the books, it shows a rare example of how even some Death Eaters thought Voldemort had gone too far in his pursuit of eternal life.

Voldemort was weakened by R.A.B. finding the locket Horcrux

Why did Regulus Black betray Voldemort?

Regulus Black likely betrayed Voldemort because he was terrified by the idea of the Dark Lord pursuing immortality by making Horcruxes.

Regulus felt like he had to delve further and further into the dark side in order to live up to his name as a member of the Black family. While Sirius rebelled and became a loyal Gryffindor, Regulus was the Seeker on Slytherin’s Quidditch team and after his school days, he became something of a Voldemort fanboy while his brother fought alongside the Order of the Phoenix.

The books leave some mystery to the reasons behind his ultimate decision to take the Horcrux. However, we can infer a few things.

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First, Regulus was shocked and appalled by the way Voldemort had simply used Kreacher as a disposable test of his security, thinking nothing of leaving the elf to die. Kreacher only survived because Voldemort underestimated the powerful elf magic that allowed him to Disapparate past the protective charms on the cave.

Also, Regulus seemed to consider the revelations about Horcruxes to be something of a turning point. Arguably, his heart had never really been in the Dark Lord’s ideology, and the prospect of Voldemort pursuing unknown corners of dark magic in order to secure eternal rule over the Wizarding World was too much for him.

He should probably have realized Voldemort was an awful tyrant much earlier, but he got there in the end, and we should all probably be thankful for that.

Kreacher in Harry Potter and the Deathly Hallows

What happened to Kreacher after the war?

Kreacher fought against the Death Eaters at the Battle of Hogwarts and died years later at the age of 666.

While Kreacher was still an awful character who hated anybody other than pure-blood wizards, he led the elves of Hogwarts into battle against Voldemort in honor of his fallen master. He ended up on the right side of the battle, whether it was for the right reasons or not.

The Harry Potter author confirmed in a tweet that Kreacher ultimately lived until the age of 666. That’s a very pointed choice of number that perhaps suggests Kreacher never stopped being a terrible bigot.

As for what the elf did with his final years, we think it’s unlikely that Harry would’ve wanted to “own” him. Instead, he would likely have felt more comfortable sending Kreacher to work in the Hogwarts kitchens. We can talk another time about whether that’s any better or if that’s just trading one form of slavery for another. The lives of house elves are pretty grim either way.

It’s established in canon that Hermione Granger went on to greatly improve the lives of house elves through her work with the Ministry of Magic, so there’s every chance that allowed Kreacher to experience true freedom towards the end of his life.

Kreacher played a crucial role in the mystery of R.A.B. in Harry Potter

For more on the adventures of the Harry Potter cast across the best movies in the series, find out how Emma Watson had her worst birthday ever on set and look back through our guide to the Harry Potter movies in order.

But for fans like us, we now have to turn our attention to the upcoming Harry Potter TV series release date for a new spin on the books. There are also some new movies on the way, with the Fantastic Beasts 4 release date hopefully due to arrive someday and a Cursed Child release date surely in the pipeline.

The creator of the Harry Potter series, JK Rowling, has made a number of transphobic remarks on social media in recent years. If you’d like to learn more about transgender equality or lend your support, here are two charities we encourage you to visit: the National Center for Transgender Equality in the US and Mermaids in the UK.