Regulus Black's Notebook

"“There’s no sense in preserving pureblood drivel.”"

- Sirius Black, on some of the content he burned from the book.

The summer before his 2nd year of Hogwarts, Sirius Black gifted Harry Potter with an old leather-bound book for his birthday. The book contained a wide array of spells and letters made by the Black family members, spanning centuries.

Sirius Black found the book while he was cleaning out Number Twelve Grimmauld Place to find valuables to sell. Knowing Harry's teacher, Gilderoy Lockhart, wouldn't be of much help in Defense Against the Dark Arts, Sirius thought it prudent to give the book to Harry to make sure he's ahead of his classmates in Dueling. Sirius also burned some of the nastier spells, despite the fact that Harry thought they belonged in a museum.

Eventually, Sirius burned the whole book, afraid Harry was sympathizing with Death Eaters or other pureblood-maniacs.

Letters

 * 1) December 25, 1972: Regulus -> Sirius; Regulus writes to Sirius, who is at Hogwarts, wishing he was home.
 * 2) October 2, 1974: Regulus -> Narcissa; Regulus congratulates his cousin on her engagement, and tells her about his time at Hogwarts, including Professor Binn arriving to class as a ghost, and his tense relationship with Sirius.
 * 3) December 25, 1974: Regulus -> Sirius; Regulus wishing Sirius a merry Chrismas, and mentions Nacissa bring her fiance over to the Black residence to meet the family.
 * 4) June 28, 1976: Narcissa -> Regulus; Narcissa consoles Regulus, as tensions with Sirius and the family reaching a boiling point. She invites him to stay with her and Lucius, to get away from the drama.
 * 5) August 23, 1976: Narcissa -> Regulus; Narcissa congratulates Regulus making Prefect, thanks him for visiting, and informs him of her husband's new position in the Ministry.
 * 6) December 25, 1976: Regulus -> Sirius; Regulus begs Sirius to make amends with their mother, in an attempt to hold their family together.
 * 7) December 25, 1977: Regulus -> Sirius; Regulus writes a short sentence wishing Sirius a happy Christmas.
 * 8) April 7, 1979: Bellatrix -> Regulus; Bellatrix confirms to meet with Regulus in Paris, as he was joining the ranks of the Death Eaters, and he will have a chance to meet Voldemort.
 * 9) May 1, 1979: Regulus -> Lucius; Regulus thanks Lucius Malfoy for the opportunity to join the Ministry, but turns him down, preferring to see what responsibilities Voldemort would ask of him first.
 * 10) October 31, 1979: Regulus -> Barty Crouch Jr; warning him not to be too extreme in ranking up among the Death Eaters, and to keep in mind the reasons they joined.
 * 11) November 2, 1979: Regulus -> Narcissa; Regulus tells his cousin he is leaving the Death Eaters, having been disenchanted by Voldemort's actions and advises her to leave as well.
 * 12) November 18, 1979: Bellatrix Lestrange -> Narcissa Malfoy; congratulating her on her pregnancy, wishing her the best health, and asking if she had seen Regulus, who apparently went missing recently.
 * 13) November 3, 1981: Barty -> Severus; Barty writes to Severus, wondering where he is, and told him about their master's disappearance and their plot to interrogate the Longbottoms for information.

Spells
Five spells are described in Regulus's notebook, and the date suggests they were taken during his sixth year at Hogwarts. The spells are: Confringo, Expulso, and Fernunculus all exist as named within the Harry Potter universe. Confringo creates a fiery explosion while Expulso repels objects in a similar manner to an explosion but with force only, no flame. Fernunculus, as its nickname "Pimple Jinx" suggests, creates pimples on the target's face.
 * Confringo (Blasting Curse)
 * Expulso
 * Fernunculus (Pimple Jinx)
 * Naresvertum
 * Incendia Incedicum

Naresvertum was invented by AidanChase in spell and concept. It turns the nose green. Harry used it in The Chamber of Secrets in a duel with Malfoy in the Alternate Universe, but it does not appear in canon, and there are no references to it in J.K. Rowling's work.

Incendia Incendicum is not named in canon, but the description of it in Regulus's letter -- a purple flame that causes internal damage -- refers to a spell used by a Death Eater against Hermione in The Battle of the Department of Mysteries. Regulus makes a note about the spell that the motion for it is similar to "semp" and that he should "ask sev" about a connection between the spells, a nod to Snape's spell Sectum Sempra.

Sirius attached a note to Regulus's notes advising Harry against using Confringo and Expulso until he had had more practice with Defense. Sirius also advised him against using Incendia Incendicum under any circumstances.

Trivia

 * Regulus Black claimed to have put the book together to collect evidence on Voldemort's Death Eaters.


 * Though there is no evidence this book exists in canon, several canon events are referenced within the book:
 * Narcissa Black gets engaged to Lucius Malfoy some time after graduating from Hogwarts.
 * Sirius Black runs away from home the summer before his sixth year.
 * Regulus betrays Lord Voldemort shortly after graduating from Hogwarts.


 * Other events are referenced in the letters that have no basis in canon:
 * It is never stated in the books that Regulus became a Prefect at Hogwarts.
 * There is no evidence that Voldemort held meetings or rallies in Paris.
 * Narcissa Black's miscarriage is never alluded to nor referenced in the Harry Potter films, games, nor novels.