The Half-Blood Prince

The Half-Blood Prince is the self-proclaimed title of Severus Snape, which he used during his time as a student at Hogwarts School of Witchcraft and Wizardry. The name is derived from his parentage: his mother, Eileen Prince, was a pure-blood witch, and his father, Tobias Snape, was a Muggle, making him a “half-blood.” Snape inscribed this moniker in his personal copy of the Advanced Potion-Making textbook. This book, and the identity of its mysterious former owner, becomes a central element in Harry Potter and the Half-Blood Prince, providing Harry Potter with extraordinary assistance in Potions while also introducing him to dangerous Dark Magic of the Prince's own invention.

The persona of the Half-Blood Prince existed during Severus Snape's years as a Slytherin student at Hogwarts from 1971 to 1978. During this time, Snape demonstrated a prodigious and innate talent for Potions and the Dark Arts that far surpassed the school's curriculum. He filled the margins of his copy of Advanced Potion-Making with corrections, improvements to potion-brewing instructions, and notes on the practical applications of various ingredients. Beyond Potions, the Prince was a gifted and creative spell-inventor. He created numerous spells and jinxes, ranging from the practical Muffliato charm to the viciously dark curse, Sectumsempra. He noted these spells were “For Enemies,” likely referring to his school rivals, James Potter and Sirius Black. The textbook served as his personal journal of magical discovery. Years later, the textbook fell into the hands of Harry Potter in his sixth year. Unaware of the Prince's true identity, Harry used the book's annotations to excel in Professor Horace Slughorn's Potions class, earning a reputation as a prodigy. The identity of the Prince remained a mystery that Harry Potter, Ron Weasley, and Hermione Granger debated throughout the year. Hermione was deeply distrustful of the Prince, believing his handwritten spells to be dangerous. Her suspicions were confirmed when Harry used Sectumsempra on Draco Malfoy with devastating results. The Prince's identity was finally and dramatically revealed by Snape himself after he killed Albus Dumbledore, taunting Harry with the words, “You dare use my own spells against me, Potter? Yes. I am the Half-Blood Prince.”

As the “Prince” was a persona of a young Severus Snape, his appearance was that of Snape as a teenager. As seen in Pensieve memories, he was a sallow-skinned boy with greasy, black hair and a hooked nose. The personality of the Prince, as revealed through his annotations, is a clear reflection of a young Snape:

• Brilliant and Arrogant: The Prince's notes are not mere suggestions but confident corrections to the published textbook, often displaying contempt for the author, Libatius Borage. He was clearly aware of his superior intellect and talent.
• Creative and Innovative: He was not content to simply follow instructions, instead experimenting and inventing new magic with remarkable success.
• Vindictive and Dark: The creation of spells like Sectumsempra reveals a cruel and vengeful streak, demonstrating an early and profound interest in the Dark Arts.
• Secretive: He chose to record his genius under a cryptic pseudonym, hiding his true identity while still claiming ownership of his work through a proud, self-aggrandizing title.

The Half-Blood Prince's skills, particularly for a student, were exceptionally advanced.

• Potions Master: The Prince possessed a mastery of Potions that rivaled or even exceeded that of professional potioneers. His handwritten improvements to recipes, such as the method for brewing the Draught of Living Death (crushing the Sopophorous bean with the flat side of a silver dagger instead of cutting it) and the recommendation to use a bezoar as an antidote to all poisons, were signs of genius.
• Spell Creation: The Prince was a highly skilled spell-inventor. Spells created by him and recorded in his textbook include:
  • Sectumsempra: A curse that lacerates the target as if slashed by an invisible sword. It is explicitly labeled “For Enemies.”
  • Levicorpus: A nonverbal jinx that hoists a person into the air by their ankle. Its counter-jinx is Liberacorpus.
  • Muffliato: A charm that fills the ears of anyone nearby with an unidentifiable buzzing sound, allowing for private conversation.
  • Minor Jinxes: He also invented a jinx to make toenails grow at an alarming rate and another to stick a person's tongue to the roof of their mouth.

• Advanced Potion-Making Textbook: The Prince's primary legacy is his annotated copy of this standard Hogwarts textbook. The book was old and battered, its pages filled with his spidery, black handwriting. On the inside front cover, he wrote, “This book is the property of the Half-Blood Prince.” It was stored in a cupboard in Professor Slughorn's classroom before being taken by Harry Potter. Harry later hid it in the Room of Requirement, where it was presumably destroyed by Vincent Crabbe's Fiendfyre.

• Eileen Prince: His mother. Snape honored her pure-blood lineage by taking her maiden name, “Prince,” as part of his moniker, while seemingly shunning the name of his Muggle father.
• Lily Evans: His closest friend during his school years. It is implied that his growing obsession with the Dark Arts, a key part of the Prince's persona, contributed to the eventual destruction of their friendship.
• The Marauders: James Potter, Sirius Black, Remus Lupin, and Peter Pettigrew were his chief antagonists at school. The dark and defensive spells created by the Prince were almost certainly developed with them in mind.
• Harry Potter: The unwitting successor to the Prince's knowledge. Harry admired the Prince's skill and intelligence, but was ultimately horrified by his dark side. The relationship is deeply ironic, as Harry was using the work of his most hated teacher to impress another.

• Half-Blood: This part of the title directly refers to Severus Snape's blood status as the son of a witch and a Muggle. It is a defiant claiming of an identity that pure-blood supremacists, like the future Death Eaters he associated with, would typically scorn.
• Prince: This name is taken from his mother's pure-blood family name, Prince. By using it, Snape connected himself to his magical heritage, a source of pride and identity in stark contrast to his unhappy life with his Muggle father.

• J.K. Rowling has stated that the identity of the Half-Blood Prince was always intended to be Severus Snape and that the clues were present from the beginning, such as Snape's own talent for Potions.
• In the film adaptation of Harry Potter and the Half-Blood Prince, Hermione Granger discovers the identity of Eileen Prince by looking through old copies of the Daily Prophet in the Hogwarts Library, a scene not present in the novel. The revelation is more of a direct research discovery rather than an inference made after Snape's confession (film).