Editing Severus Snape (section)

==== ''Harry Potter and the Half-Blood Prince'' ====
In the second chapter of ''[[Harry Potter and the Half-Blood Prince]]'', [[Bellatrix Lestrange]] and [[Narcissa Malfoy]] visit Snape at his home in [[Spinner's End]]. Narcissa's son [[Draco Malfoy|Draco]] has been given a difficult task by Voldemort, and Narcissa swears Snape to an [[Unbreakable Vow]] that he will protect Draco, help him complete Voldemort's task, and finish the task himself if Draco fails. When questioned by Bellatrix about his loyalties, Snape says he has been working for Voldemort ever since Voldemort's return, and explains his actions in the previous books in that light. He points out that gaining Dumbledore's trust and protection has kept him out of Azkaban and free to operate on Voldemort's behalf.<ref name="Spinner's End">{{HPref|book=6|chapter=2}}</ref>

At the start-of-term feast at Hogwarts, Dumbledore announces Snape as the new [[Defence Against the Dark Arts]] professor. [[Horace Slughorn]], Snape's own former teacher, comes out of retirement and replaces him as Potions Master. With Snape no longer teaching Potions, Harry enrolls in Slughorn's class and is lent an old textbook until his new one arrives. Harry finds [[marginalia]], including a variety of hexes and jinxes seemingly invented by an unknown student, and substantial improvements to the book's standard potion-making instructions. The text is inscribed as being "the Property of the Half-Blood Prince". The notes greatly bolster Harry's performance in Potions, so much so that he impresses Slughorn. Snape, who maintains that he "never had the impression that [he] had been able to teach Potter anything at all", is suspicious of Harry's newfound Potions success.<ref name="The Unbreakable Vow">{{HPref|book=6|chapter=15}}</ref>

Later, during a fight with Draco, Harry casts one of the Prince's spells marked "For Enemies," and is horrified by the devastating wounds it inflicts to Draco's face and chest. Snape rushes to the scene and heals Draco, then interrogates Harry regarding the spell, using [[Legilimency]] to extract the source of Harry's knowledge (the Potions textbook) from Harry's mind. When Snape insists that Harry show him his Potions textbook, Harry hides the Prince's book and gives him [[Ron Weasley]]'s book instead. As punishment for the attack and knowing Harry is lying about the textbook, Snape assigns Harry detention during the final [[Quidditch]] match of the year.<ref name="Sectumsempra">{{HPref|book=6|chapter=24}}</ref>

Before leaving Hogwarts to accompany Dumbledore in locating another [[horcrux]] – part of Voldemort's soul – Harry discovers from Professor Trelawney that it was Snape who overheard the prophecy and told it to Voldemort, resulting in Voldemort hunting down Harry and his parents. Despite this and Harry's angry questions, Dumbledore avers his trust in Snape. Returning to Hogwarts after retrieving Voldemort's [[Horcrux]], Harry and Dumbledore alight atop the school's astronomy tower. Gravely weakened by the horcrux's protective potion, Dumbledore tells Harry he must fetch Snape, but before Harry can leave, Draco suddenly arrives, intending to carry out Voldemort's order to assassinate Dumbledore, closely followed by other Death Eaters (followers of Voldemort), and Snape. Snape interrupts the planned murder, killing the headmaster himself.<ref name="The Lightning-Struck Tower">{{HPref|book=6|chapter=27}}</ref> Harry, who is paralysed under his [[Cloak of Invisibility (Harry Potter)|invisibility cloak]] by Dumbledore for his own protection, witnesses the kill, and is released upon Dumbledore's death. Enraged, he pursues Snape, Draco, and the Death Eaters as they flee the castle. Snape easily blocks Harry's spells and jeeringly points out Harry's mistakes, but never strikes back. During the confrontation, Snape reveals himself as the eponymous "Half-Blood Prince" (being the [[Half-blood (Harry Potter)|half-blood]] son of Muggle Tobias Snape and [[Pure-blood (Harry Potter)|pure-blood]] Eileen {{em|Prince}}). Snape passes through the school gates and [[Disapparition|Disapparates]] with Draco in tow at the book's end.<ref name="Flight of the Prince">{{HPref|book=6|chapter=28}}</ref> The full relationship between Dumbledore and Snape and the reason for Snape's actions remain unknown until the final book. In an interview, Rowling mentioned that at this point in the series, the Harry–Snape relationship has become "as personal, if not more so, than Harry–Voldemort."<ref>{{cite news |title=The Leaky Cauldron and MN Interview Joanne Kathleen Rowling – Part 1 |url=http://www.the-leaky-cauldron.org/2007/07/28/jkrhbp1/ |access-date=8 February 2022 |publisher=[[The Leaky Cauldron (website)|The Leaky Cauldron]] |date=28 July 2007}}</ref>