- Harry: "You think the Horcrux is in there, sir?"
- Dumbledore: "Oh yes. But how to reach it? This potion cannot be penetrated by hand, Vanished, parted, scooped up, or siphoned away, nor can it be Transfigured, Charmed, or otherwise made to change its nature. I can only conclude this potion is supposed to be drunk."
- — Harry and Dumbledore discuss the potion guarding a Horcrux[src]
The Emerald Potion, also known as the Drink of Despair, is a mysterious potion which induces fear, delirium, and extreme thirst. According to Dumbledore, the potion cannot be penetrated by hand, vanished, parted, scooped up, siphoned away, Transfigured, Charmed, or otherwise made to change its nature in any way. It can only be drained away by drinking. As such, this potion is meant for protecting something of extreme importance. As the potion typically does not kill the victim, it nonetheless makes them very weak and vulnerable. As such, for a more complete security, something else should be there to be prepared to attack the victim once they finish drinking the potion.
Lord Voldemort used this potion as part of the defences to protect one of his Horcruxes, Salazar Slytherin's Locket, within The Cave. As one person would not be able to drink the entire contents without collapsing from the terrible effects, a second person would be required to force feed the potion, which Voldemort considered impossible due to the enchanted boat leading to the cave being designed to carry only one adult Wizard. This particular defence was able to be breached on a small number of circumstances through using underage wizards or magical creatures such as house elves, presumably because Voldemort underestimated them.
After he had turned Slytherin's locket into a Horcrux, Lord Voldemort decided to use an isolated cave as a secure hiding place. The critical part of this security was a special potion that was apparently of his own creation. A stone basin existed in the middle of the subterranean lake, and the locket was placed inside at which point it was then immersed in the potion. In order to test the effectiveness of the defences placed around the locket, Voldemort asked his Death Eaters to let him use a house elf. One of them, Regulus Black, volunteered, and ordered his house-elf, Kreacher, to obey Voldemort's instructions and when finished to come back to 12 Grimmauld Place.
Voldemort tested all of the defences, including the potion. As Voldemort had hoped, the potion incapacitated Kreacher, who he left behind to die. However, Voldemort did not realise that his security measures would not prevent a house-elf from Disapparating, as he failed to understand that house-elves would have powers that wizards did not. Thus Kreacher was able to return home and report the secrets of the cave to Regulus Black.
First attempt on the locket
Regulus was infuriated by Voldemort's treatment of Kreacher, and decided to sabotage Voldemort's quest for immortality. He had worked out, from various subtle hints, that Voldemort had created a Horcrux, something that deeply frightened Regulus. He did not tell anyone about this — not even Kreacher — in order to help ensure the safety of his family. He asked Kreacher to take him to the cave, and then drank the potion himself, allowing Kreacher to swap the Horcrux for another locket. Regulus had ordered Kreacher to leave him in the cave, destroy the locket, and to never tell his family what had happened. Kreacher was not able to destroy the locket, despite many attempts, and the original locket remained at 12 Grimmauld Place until it was stolen by Mundungus Fletcher.
Second attempt on the locket
Albus Dumbledore had realised that Tom Riddle had likely created several Horcruxes, and began a quest to find where they were hidden. One story he investigated was from Tom Riddle's days in his orphanage, where he had terrified two of his fellow orphans during a visit to the coast. As part of this investigation, he discovered an area that had been altered by powerful magic. On the 30th of June, 1997, Dumbledore and Harry Potter set off to the cave to obtain the Horcrux. After penetrating the outer defences, Harry and Dumbledore arrived at the island and discovered that the Horcrux was immersed in a glowing, green, potion. After determining that the potion could only be removed if it was drunk, Dumbledore conjured a goblet and began to drink the potion.
Dumbledore started drinking, and it took three cups of the potion before he was noticeably affected. The first symptom of the potion was pain. Then, much like a dementor, it apparently made the drinker relive his worst memories. Finally, it caused intense thirst. Since the cave would cause any water that was conjured to immediately disappear, this would cause the individual to drink from the lake, which in turn would wake the Inferi, who would drag the individual into the lake to drown. Harry and Dumbledore were able to escape after Dumbledore conjured a lasso of fire, as Inferi — like all dark creatures — feared fire, light, and heat.
The potion has an emerald green colour to it, and glows phosphorescently. As such, a green glow can be seen from the basin on the island in the middle of the lake as far away as the far end of the cave. While Dumbledore declared that the potion's nature could not be changed in any way, Lord Voldemort was able to turn the potion "crystal clear" in one occasion to check the locket, most likely because he alone knew how to alter the potion's characteristics.
- "Kreacher drank, and as he drank, he saw terrible things... Kreacher's insides burned... Kreacher cried for Master Regulus to save him, he cried for his Mistress Black, but the Dark Lord only laughed... He made Kreacher drink all the potion... He dropped a locket into the empty basin... He filled it with more potion..."
- —Kreacher describing when Voldemort forced him to test the potion's defences.[src]
While its effects are not completely known, it acts both like a poison and an antidote. The potion would seem to cause the drinker intense pain (described as a burning sensation in the insides), followed by forcing them to experience terrible things, most likely their worst memories and fears, followed finally by extreme thirst after drinking the last of it. However, Albus Dumbledore noted that the potion's effect could not be fatal, as Voldemort would not want to immediately kill anyone who discovered the cave and the horcrux within it until he had the time and opportunity to learn how they had discovered its existence in the first place.
Dumbledore's screams of "kill me" could either indicate a resurfacing of the memory of his sister's death (as in, "kill me instead") or a request to be delivered from the intense physical pain he was experiencing, or both. In 1998, while telling Aberforth Dumbledore about what happened when his brother drank the potion, Harry mentions that he believed that Dumbledore was reliving the 3-way duel that broke out amongst them and Grindelwald that resulted in their sister Ariana's death. This was something that Dumbledore felt guilty about for the whole of his life after the event. While it was likely that this was what Dumbledore was seeing this duel and his sister's death, he did not mention out loud either event while he was drinking the potion.
Behind the scenes
- The potion is unnamed in the books, films, and video games. The piece of film's soundtrack which plays over the scene of Dumbledore consuming the potion is titled "The Drink of Despair". Pottermore refers to it as "Emerald Potion".
- In the movie, the potion has a murky black colour. It is emerald green in the books.
- Also, in the book version, Dumbledore conjured a crystal cup out of thin air to drink the potion, while in the movie version, there was a seashell-shaped cup placed on top of the basin (originally a crystal cup in the script).
- Dumbledore's theory that the potion would not kill its drinker, but rather stop him in some way from reaching the Horcrux and possibly notify Voldemort (so that he could torture and interrogate the drinker) proved wrong; there was no alarm system as Voldemort was not notified when either Regulus and Kreacher or Albus Dumbledore and Harry entered the cave. The potion was not immediately fatal, but was specifically designed to force the drinker to either go to the lake and be drowned by the Inferi or to die of thirst. It is unknown whether Dumbledore genuinely believed what he told Harry, or whether that was to persuade Harry to help him drink the potion. Alternatively, Voldemort may have preferred a more torturous method of death for those who dared to try to destroy his Horcruxes.
- Both known human drinkers, Albus Dumbledore and Regulus Black, were the only two people who independently discovered that Voldemort had created Horcruxes. (Harry, Ron and Hermione were told.) For Regulus Black, this was the first (and only) attempt at finding one of Voldemort's Horcruxes, while Dumbledore had already found and destroyed the ring Horcrux and was already dying from the ring's curse when he drank the potion. They were the only two drinkers who willingly drank the potion, knowing that they had to do so in order to obtain the Horcrux.
- Both Albus Dumbledore and Regulus Black died shortly after drinking the potion (and knew that they were going to): Regulus Black presumably believed that he couldn't continue opposing Lord Voldemort and live, whereas Dumbledore only had a few months to live (due to being cursed by putting on the ring) and had ordered Severus Snape to give him a painless death. Regulus ordered Kreacher to leave him to die after he had drunk the potion and was taken by the Inferi while drinking from the lake to quench his thirst, while Dumbledore was killed by Severus Snape on Dumbledore's orders.
- The torture inflicted by the potion may have contributed to Kreacher's bitter personality (along with Regulus' and Walburga's deaths, being unable to tell his family about Regulus's death, living alone with the Locket Horcrux and Walburga's portrait and Sirius Black's cruel treatment of him) and his unhealthy appearance (possibly along with age).
- In LEGO Harry Potter: Years 5-7, the potion is kept in a water-cooler rather than a basin.
- Harry Potter and the Half-Blood Prince (First appearance)
- Harry Potter and the Half-Blood Prince (film)
- Harry Potter and the Half-Blood Prince (video game)
- Harry Potter and the Half-Blood Prince (soundtrack) (First identified as Emerald Potion)
- Harry Potter and the Deathly Hallows (Appears in vision(s))
- Harry Potter and the Deathly Hallows: Part 1 (Appears in vision(s))
- LEGO Harry Potter: Years 5-7
- Pottermore (Mentioned only)