Motifs are recurring structures, contrasts, or literary devices that can help to develop and inform the text’s major themes.
Much of the central action of Harry Potter and the Half-Blood Prince centers on information that is overheard or gathered by covertly following suspicious characters—at Hogwarts and beyond, wizards constantly watch each other. Initially, Harry, Ron, and Hermione follow Draco Malfoy to Borgin and Burkes and then eavesdrop on his conversation with Borgin. Later, Harry has Kreacher and Dobby follow Draco Malfoy as Draco moves around Hogwarts, and Harry constantly uses his Marauder’s Map to locate Malfoy when he is on the school grounds. Meanwhile, Tonks appears to be following Harry, popping up unexpectedly whenever it looks like he might be about to get into trouble. Draco Malfoy gets caught by Filch while trying to eavesdrop on or sneak into Slughorn’s Christmas party. After Snape drags him off for reprimanding, Harry uses his Invisibility Cloak to listen in on their conversation, confirming his suspicions of Snape.
Lord Voldemort’s name is rarely spoken in the Wizarding world, as most wizards are too frightened to let the words slip from their mouths. Instead, they dodge around the issue by calling him “You know who” or “He who shall not be named.” Still, Harry and Dumbledore both regularly say Voldemort out loud, inadvertently expressing their lack of fear and demonstrating their strength in the face of evil. When Harry and Dumbledore use the Pensieve to view Dumbledore’s memory from his first meeting with Voldemort as headmaster of Hogwarts, we see Dumbledore only referring to Voldemort by his real name, Tom Riddle. This practice makes the young Voldemort extremely irritated, and he repeatedly requests that Dumbledore not call him Tom. Likewise, when Dumbledore first visits Voldemort at the orphanage, we see Voldemort express extreme distaste for his given name, which he received from his long-lost Muggle father, dubbing it too “common.” Part of Voldemort’s hatred of his given name stems from his anger at his father, who left his mother when she was pregnant.
Although Rowling is unclear as to exactly where Severus Snape’s allegiances lie, Snape is obviously working as a double agent and is either lying to Dumbledore or lying to Voldemort. This undercurrent of duplicity is consistently present in Harry Potter and the Half-Blood Prince, where nothing is as it seems, and no one is sure who is working for whom. With the Imperius Curse being used frequently, innocent people are often caught committing crimes, and the Ministry continues to imprison guiltless wizards just to give the appearance that they are making progress in the fight against Voldemort. Meanwhile, Draco Malfoy is continuing to pretend that he is a regular Hogwarts student and not carrying out Voldemort’s bidding. Even Draco’s mother, Narcissa Malfoy, becomes duplicitous, imploring Snape to help her protect her son from Voldemort’s vengeance.