Chapter 28 of Harry Potter and the Half-Blood Prince: Flight of the Prince
Snape forces Draco Malfoy back down the tower stairwell, followed by the Death Eaters. Harry, released from the paralyzing spell by Dumbledore's death, Petrifies the last one and charges down the steps after the others. At the bottom is a melée of Hogwarts students, teachers, and Order of the Phoenix members fighting Death Eaters. Ginny is dueling Amycus Carrow. Harry Jinxes Amycus, as Snape and the other Death Eaters break away and run.
At the the front entrance, Harry sees a Death Eater on the grounds, Snape and Draco further away. The large blond Death Eater casts multiple curses at Hagrid, but his massive body deflects them. Harry hurls the Prince's spells at Snape, but Snape easily blocks every one, proclaiming he created them—he is the Half-Blood Prince. Although Snape blocks every curse Harry casts, he does nothing to harm him and continually tells him what he is doing wrong. Snape prevents the other Death Eaters from attacking Harry, claiming he belongs to Voldemort. Harry calls Snape a coward. Enraged, Snape jinxes Harry before escaping with Draco and the other Death Eaters.
Seeing that Hagrid's hut is afire, Harry, finding his dropped wand, helps douse the flames. Hagrid cannot believe that Dumbledore is dead, but as he and Harry approach a huddled crowd, Dumbledore's twisted corpse is seen lying on the ground. Harry removes the locket from the old wizard's robe pocket. Inside is a note reading:
- To the Dark Lord
- I know I will be dead long before you read this
- but I want you to know that it was I who discovered your secret.
- I have stolen the real Horcrux and intend to destroy it as soon as I can.
- I face death in the hope that when you meet your match,
- you will be mortal once more.
Harry chases Snape in a blind rage and with one intent: to kill him. Snape, who easily eludes him, has every opportunity to murder or capture the outmatched Harry. Instead, he merely deflects Harry's ineffective curses. Snape continually does nothing to harm Harry, and actually tells him what he is doing wrong and how to correct it. He also prevents the other Death Eaters from cursing him. Why? Although he claims he wants Harry left alive for the Dark Lord, he could easily have stunned and presented him to Voldemort. By leaving Harry at Hogwarts, Snape not only risks having the determined and vengeful Harry single-mindedly hunting him down, but also the Dark Lord's deadly wrath by letting his number one enemy remain alive and free. For Harry, learning that his admired mentor (the Half-Blood Prince) is actually his hated nemesis is shocking and revolting.
It is interesting to note Snape's enraged reaction when Harry calls him a coward, even though murdering the unarmed Dumbledore is an extremely cowardly act, as was his subsequent running away. One must wonder if there is something beyond what Snape has actually done, some way in which Snape can still see himself as honourable and living up to some form of standard.
Harry learns that someone with the initials R.A.B. stole the true Horcrux from the sea cave. However, in that chapter, it was learned that two people were needed to recover the locket from the basin on the island. R.A.B. must have had some assistance. Although R.A.B. is probably dead, if someone else was involved, it is possible he or she may still be alive and could provide valuable information. It also appears that R.A.B. may have known about the prophecy, as that person refers to Voldemort meeting his match. However, it also seems that R.A.B. may have mistakenly believed that the locket was the only Horcrux, as he seems to assume that destroying it will be sufficient to make Voldemort mortal once more.
- Why does Snape not curse or kill or capture Harry during his escape? Why would Snape tell Harry what he is doing wrong as Harry attempts to curse him?
- Who might R.A.B. be?
- Why would Snape react so strongly when Harry called him a coward?
- During his duel with Snape, why didn't Harry cast any spells nonverbally, one of Snape's first lessons in Defence Against the Dark Arts?
In the final book, it is revealed that "R.A.B." are the initials of Regulus Black (Sirius' brother). Regulus' middle name is "Arcturus," a name appearing on the Black Family tree. The person who stole the Horcrux had to be someone close to Voldemort, most likely a Death Eater, which Regulus Black was. It is usually, although not exclusively, Death Eaters who refer to Voldemort as the Dark Lord. Our understanding of the timing leads us to believe that Regulus cannot have been aware of the prophecy, as it likely had not yet been made.
It was believed that Regulus had gotten into Voldemort's hierarchy, and not liking what he found, wanted out, but had been killed. This is not what actually happened. Kreacher will know more about it, as he was involved; it is noted in the Analysis that it would have taken two people to remove and replace the locket, and that will turn out to have been Regulus and Kreacher. Regulus decided that he wanted out, but rather than simply leaving (and being killed), he had decided to make his death count for something. Having learned of the existence of a Horcrux, and having determined, from Kreacher, where something valuable was hidden, Regulus determined to destroy what he believed was Voldemort's only Horcrux.
Snape is this book's titular Half-Blood Prince, and the textbook that Harry used so successfully was originally Snape's. The book was fifty years old when Harry looked at it, which seemed to rule out his father owning it, as well as Snape. However, it is learned later that Snape comes from a poverty-stricken household, and likely had second-hand textbooks. From seeing Ginny's books in her first year, we know used books are available, and so it is entirely possible that the young Snape would have them. Quite possibly, having to use a text that was already a quarter century old, would have increased his dislike of the more-privileged students.
In the previous year, as Sirius, Harry, and the Weasleys sorted through the various family heirlooms at 12 Grimmauld Place, the Black family home, a heavy locket that none of them can open is tossed aside. Unknown to anyone, Kreacher saved the locket, keeping it hidden in his cupboard, though it will be stolen by Mundungus Fletcher, and then extorted from him by Dolores Umbridge. It will turn out to be the Horcrux locket, once belonging to Salazar Slytherin, and can only be opened by someone speaking in parseltongue. That would explain why no one could open the locket, and why Regulus was unable to destroy it as he intended. Since no one suspected the locket was a Horcrux, Harry did not speak Parseltongue to it (although he does so later to destroy it). Voldemort probably did not create the charm that prevented the locket from opening, though he was likely glad that it was difficult as it protected his Horcrux within. Slytherin's descendants were proud of their ability to speak to snakes; it is entirely possible that Slytherin himself, when he created the locket, charmed it to prevent it from opening unless spoken to in Parseltongue.