Although Ron and Hermione still aren’t speaking, Harry tells them both about his new assignment. Ron is sure that Harry can get anything out of Slughorn, who loves him; but Hermione is perplexed, as even she has no idea what a Horcrux is. Ron thinks that Harry should approach Slughorn after Potions but when he shares this plan with Hermione, she explodes in frustration, asking sarcastically “when Won-Won’s judgment has ever been faulty.”
Generally, Harry relies on both Ron and Hermione to help him confront problems; however, the conflict over Lavender has made group planning almost impossible. This disastrous relationship doesn’t just cause discord between Ron and Hermione, it strengthens Harry’s belief that romance is inherently threatening to friendship.
Today’s assignment in Potions is to create an antidote to a given poison. Except for Hermione, no one understands the principles behind the task; without precise instructions from his book, even Harry can’t perform it. He doesn’t want to be revealed as a fake, especially not today, so he’s excited to see that at the bottom of a list of popular antidotes in the book, the Prince has scrawled “bezoars.” Harry remembers Snape describing this magical stone as a protection from most poison, so he retrieves one from the supply closet and shows it to Slughorn in place of a brewed antidote. Slughorn thinks it’s a fantastic joke, but Hermione is furious.
The fact that the Half-Blood Prince’s instructions have saved Harry once again increases his trust in the book, even though he still knows nothing about its origins or the character of its original owner. Although Harry is constantly arguing against blind trust of Snape and Draco, when it’s convenient for him he also extends blind trust to people who might not deserve it.
When the bell rings, Harry lingers behind and without preamble asks Slughorn what he knows about Horcruxes. Slughorn grows pale and immediately deduces that Harry is acting on Dumbledore’s orders; he says forcefully that he knows nothing about Horcruxes and leaves the room in anger. Resentful of his stunt with the bezoar, neither Ron nor Hermione is particularly sympathetic about his failure. Harry decides to drop the issue for now and cultivate a closer relationship with Slughorn. Hermione scours the library for references to Horcruxes, without any success.
Unsurprisingly, Hermione was right in predicting that Ron’s plan wouldn’t work. At the same time, her inability to find any mention of Horcruxes in the library suggests that the group’s usual methods of going about a difficult task won’t work this time.
Meanwhile, the sixth-years gather for their first Apparition lessons. As everyone spreads out to practice, Harry positions himself right behind Draco, who is having a heated argument with Crabbe. He hears his nemesis sharply admonish his sidekick that he and Goyle have to keep watch for him without asking questions. Harry taunts Draco that he always tells his friends what he’s doing if he wants them to keep watch, but as Malfoy draws his wand McGonagall shouts for him to be quiet.
Like the young Tom Riddle and his gang, Draco and his sidekicks Crabbe and Goyle are foils to Harry and his friends. Draco constantly treats the other two boys like servants, expecting them to support him without telling them what he’s doing. Ultimately this makes him vulnerable, while Harry’s trio’s more equitable dynamic contributes to their strength.
The instructor explains the procedure for Apparating inside a small hoop in the floor. However, when the students actually try most of them just fall over. No one manages to Apparate successfully, although Susan Bones briefly severs one of her legs in the attempt.
If being able to Apparate is a test of adulthood, the difficulty of achieving this feat reflects that growing up is rarely a seamless process – even in the world that existed prior to Voldemort’s rise.
As he leaves the Great Hall, Harry sees Draco rushing off ahead. He runs to his dormitory and produces the Marauders’ Map, looking for his nemesis. Ron soon finds him in the Slytherin common room, but Harry decides to keep an eye on him from now on. In the next few days he finds nothing unusual. Crabbe and Goyle frequently wander around the castle, but they do so without Draco – who, in fact, sometimes disappears off the map altogether.
As an orphan, Harry often feels that he lacks parental care; however, in bequeathing him the Mauraders’ Map, which helps him solve many dilemmas and contributes to his investigations now, his father is effectively aiding him from beyond the grave.
Ron is disgruntled to find that a Hogsmeade trip scheduled for his birthday has been cancelled due to security concerns. On Ron’s birthday morning, Harry watches him open presents while rummaging through his trunk for the Maruader’s Map. He barely looks at the watch Ron has received from his parents, too busy scouring the map for Draco, who isn’t visible anywhere in the castle. Ron offers Harry a chocolate from one of his birthday packages, but Harry turns it down.
Harry’s growing obsession with Draco doesn’t just take up his time, it affects his behavior toward his friends. At this point, it’s seeming less like a legitimate investigation into wrongdoing and more like an unhealthy manifestation of his general anxieties, which isolates him from those around him.
In frustration, Harry finally puts the map away; but when he turns back to Ron, his friend is staring strangely into space. To Harry’s surprise, Ron says that he’s not hungry and doesn’t want to come to breakfast. Suddenly, he bursts out that he “can’t stop thinking about” a woman who “doesn’t know he exists.” Thinking he’s talking about Lavender, Harry sarcastically reassures Ron that his girlfriend is too busy snogging him to be unaware of his existence. Shockingly, Ron says that he’s talking about Romilda Vane, with whom he’s in love.
Even though Ron’s passion for Romilda is clearly engineered by a love potion, it also echoes his relationship with Lavender – sudden in onset, and based on obsession and infatuation rather than long-standing friendship and trust. In a sense, this episode helps differentiate Ron’s feelings for Lavender from those for Hermione.
Harry thinks Ron is joking and turns to leave – only for his friend to punch him across the face. Reacting instinctively, Harry hoists Ron into the air with the Levicorpus spell, then sees the box of chocolates lying on the floor and realizes they were the ones Romilda once gave Harry, rather than a present for Ron. They must have fallen off his bed. Harry tries to explain this to Ron, but he’s completely dazed by the love potion and only asks Harry to introduce him to Romilda.
The fact that Ron has unwittingly ingested such a strong potion, which Romilda tried to slip Harry, reflects the danger to which Harry’s fame exposes him, even from well-meaning people.
Harry is tempted to laugh at Ron and see what he does under the effects of the potion, but he reflects that they’re “supposed to be friends.” Letting Ron down, he blithely says that they should go to Professor Slughorn’s office, where Romilda is receiving extra Potions tutoring. On their way, they run into an enthusiastic Lavender whom Ron rudely brushes off, telling her that he’s going to meet Romilda.
Even though Harry is often reluctant to think about his feelings or those of other people, here he takes care of Ron when his friend is most vulnerable. Meanwhile, the love potion does have an unintended benefit in sparking the unraveling of Ron and Lavender’s relationship.
When a bleary-eyed Slughorn answers his office door, Harry quietly asks if he can brew an antidote for the potion. Reluctantly, he lets them in. While he brews the antidote, Ron looks around anxiously, awaiting Romilda’s arrival. Slughorn gives Ron a drink, telling him it will soothe his nerves; as soon as he downs it, his face fills with dejection and he collapses onto an armchair. Slughorn remarks that he needs something to cheer him up and opens a bottle of mead, which he was intending to give to Dumbledore for Christmas.
Even though it elicits all the emotions of love – from euphoria to despair – in Ron, the potion doesn’t actually cause real love. In this sense, it’s a warning to both Ron and Harry to examine the source of their emotions, rather than blindly following their dictates.
Downing his glass of mead before the other two, Ron falls to the floor immediately, foaming at the mouth. Harry yells for Slughorn to do something, but the professor just looks on in horror. Frantically, Harry rifles through his supply cabinet until he finds a bezoar, which he shoves into his friend’s mouth. Ron shudders once and then lies limp and still.
This is one of many instances in the novel when a normally capable adult falls short in a crisis. Even though Slughorn is the Potions professor, it’s only Harry who’s clearheaded enough to find an antidote – he’s forced to demonstrate his maturity in this situation.