Professor Severus Snape (9 January 1960[1] – 2 May 1998)[2] was an English half-blood[3] wizard serving as Potions Master (1981-1996), Head of Slytherin House (1981-1997), Defence Against the Dark Arts professor (1996-1997), and Headmaster (1997-1998) of Hogwarts School of Witchcraft and Wizardry as well as a member of both the Order of the Phoenix and a Death Eater. His double life played an extremely important role in both of the First and Second Wizarding Wars against Voldemort.

The only child of Muggle Tobias Snape and pure-blood witch Eileen Snape (née Prince), Severus was raised in the Muggle dwelling of Spinner's End, which was in close proximity to the home of the Evans family, though in a poorer area. He met Lily and Petunia Evans when he was nine. He fell deeply in love with Lily upon their meeting and became a close friend of hers.[7]

Severus started at Hogwarts with Lily in the 1971–1972 school year, where he was Sorted into Slytherin House. This put him in the same year as Lily but unfortunately for him she was Sorted into Gryffindor House. Severus became the immediate enemy of James Potter and Sirius Black and was a frequent victim of their bullying. This led him to be irritable towards James's son Harry when he was a professor. Snape, when young, developed a passion for the Dark Arts, which increased as his desire for revenge against his bullies grew stronger.

Snape became acquainted with a group in Slytherin House, many of whom were pure-blood supremacists. This put his friendship with Lily, a Muggle-born, under great strain until it was eventually broken in their fifth year.[6][7] In a misguided attempt to win back Lily's affections,[18] Snape joined the Death Eaters along with a group of his fellow Slytherins.

Severus was made a member of the Slug Club presumably because of his talent in Potion-making. Horace Slughorn even kept a picture of him as a student, clutching his copy of Advanced Potion-Making. However, Horace did not actually have many hopes for Severus's future, as his photograph was kept behind many others.[19]

As an active Death Eater, one of Snape's biggest contributions was letting Lord Voldemort know about the prophecy Sybill Trelawney made to Dumbledore. This part of the prophecy could have applied to either Harry Potter or Neville Longbottom, who was also born at the end of July 1980 to parents who were members of the Order. Once Lord Voldemort decided to target the Potters over the Longbottoms, Snape begged Voldemort to at least spare Lily. Voldemort ostensibly agreed, but did not actually follow through on this promise due to Lily's refusal to allow him to kill Harry, resulting in her sacrificing her life to save her son's.

Shortly before Lily Evans was murdered by Lord Voldemort, Snape changed sides and became a member of the Order of the Phoenix as well as a double agent during the Second Wizarding War. With tremendous difficulty, Snape prevented Voldemort from learning the truth about his loyalties.

Despite the opinions of most others including Harry during his early life, Albus Dumbledore trusted Snape for reasons that were kept between them both until their deaths. Despite Snape killing Dumbledore, it is learned that they had a special agreement for him to do so. When he died, it was revealed that his deep strong love for Lily Evans caused him to redeem himself, joining Dumbledore's cause for her protection (and, after her death, that of her son) from Lord Voldemort.[7]

The relationship between Dumbledore and Snape would be one of unusually strong loyalty, so much so that Snape agreed to kill Dumbledore upon the latter's own request. Before Dumbledore's death, Snape promised to protect the students of Hogwarts from the Death Eaters, who would inevitably take control of the Ministry of Magic as well as the school.[7]

Snape later participated in the Battle of Hogwarts but was murdered by Lord Voldemort who mistakenly believed that Snape was the master of the Elder Wand (an immensely strong and powerful wand that Voldemort deeply desired, as well as one of the Deathly Hallows)[20] when in reality, Harry Potter was the true master of the Elder Wand, because Draco Malfoy had disarmed Dumbledore on the night of Dumbledore's death at the top of the Astronomy Tower, and Harry had disarmed Draco at Malfoy Manor.[21]

After Snape's death, Harry Potter ensured that his portrait remained at Hogwarts, honouring him as a hero, despite their significant personal differences.[21] In addition, Harry later named his second son Albus Severus Potter in honour of Dumbledore and Severus, both of whom were an inspiration in Harry's life after the Battle of Hogwarts. Harry also was influenced by Severus's Hogwarts house, and freely admitted that his son Albus could choose Slytherin if he wished.[22]

Early life (1960–1971) Lily Evans: "Doesn't your dad like magic?" Severus Snape: "He doesn't like anything, much." — Discussion of Snape's family and home life[src] Severus Snape was born 9 January 1960 to Tobias Snape, an abusive Muggle, and Eileen Prince, a neglectful pure-blood witch.[23] He began to identify with his mother's family and created a secret nickname from his mother's maiden name, calling himself the "Half-Blood Prince". It is implied that Severus was friendless and uncared for by his parents. This lack of care largely shaped Severus's bitter disposition and cruel behaviour later in his life.

Severus grew up at Spinner's End, a shabby suburb of Cokeworth.[24] This area of town was near a dirty river and full of dilapidated houses, disused factories and broken down street lamps. Through the rest of his life, Severus continued to return there when he was not at school. The young Severus is depicted as being unwashed and wearing ill-fitting clothes "that were so mismatched that it looked deliberate". As a child, Severus was neglected and his parents often fought with one another. He could not wait to leave for Hogwarts at the end of the summer.[7] Despite this, one of his favourite foods from his childhood was Holiday Blancmange, which persisted into his adult years.[25]

Lily Evans and her family lived in the same town, close to Spinner's End. After watching her for some time, Severus noticed her evident magical abilities and began making friendly overtures. The two bonded quickly and it appears that he was very interested in Lily right from the beginning, though she only regarded him as a good friend. During this time he also developed a contempt towards her older sister, Petunia, who made disparaging comments about his clothes and residence.[7]

Information from Severus's own memories of his first interactions with Lily and Petunia suggests that he was an awkward child with poor social skills. Even when it was important to him to make a good impression, he always seemed to have trouble doing so.[7]

Hogwarts years (1971–1978) James Potter: "'Gryffindor, where dwell the brave at heart!' Like my dad. Got a problem with that?" Severus Snape: "No. If you'd rather be brawny than brainy —" Sirius Black: "Where are you hoping to go, seeing as you're neither?" — James, Snape, and Sirius have an unpleasant first meeting[src]

Severus attended Hogwarts School of Witchcraft and Wizardry as a student from 1971-1978 and was Sorted into Slytherin House, at that time led by Potions master Horace Slughorn. On the way to Hogwarts for his first year, Severus sat with Lily Evans on the train. While on the train they met James Potter and Sirius Black. This encounter between the three of them revolved around a disagreement regarding what Hogwarts house was the best. This hostile first encounter would set the tone for the antagonism between the three of them for the rest of his life.[7]

Sorted into Slytherin House upon their arrival at the school, classmates would later state that Severus excelled in the Dark Arts from an early age. At the age of eleven, he knew more curses and hexes than most of the seventh year students, according to Sirius Black.[26] He was credited with creating a good number of popular spells like Levicorpus, Liberacorpus, Muffliato, and curses like Langlock, the Toenail Growth Hex, and his signature curse that he invented himself, Sectumsempra.[27] He reportedly was friends with a gang of Slytherins who later became Death Eaters, including Avery, Mulciber, Bellatrix Black, Rodolphus Lestrange, Evan Rosier and Wilkes.

Severus also had contact with Lucius Malfoy, who was a prefect during his first year and greeted him kindly when he was Sorted into the Slytherin House.[7] Most likely the two had good rapport at Hogwarts (which could also be a reason why Narcissa Malfoy trusted Severus to take care of Draco Malfoy and why he seemed to favour Draco during his later teaching years even when Draco refused it in the task to kill Dumbledore).

Remus Lupin and Peter Pettigrew were also classmates of Severus.[6] Around the same time, he also got acquainted with another notorious troublemaker; a Fifth year student by the name of Patricia Rakepick who not only was in the same house as his new school rivals, but also actively sought to mentor her younger schoolmates in the art of mischief-making without getting caught: While popular with many of their peers for her, she was, on the other hand, strongly disliked by most of the teachers for her excessive rebellious streak, frequent rule-breaking and the bad influence she was on her younger housemates.[28]

No less discontent with her behaviour than their professors were, Severus's mistrust in Rakepick ran deeper still; she was an avid advocate for the existence of the fabled Cursed Vaults of Hogwarts. While her claims were dismissed by the faculty of the day, young Snape, however, was not so certain; seeing her as uncommonly ambitious for a Gryffindor and, he recognised, far from stupid, he eventually came to question her motives and her intentions for the vaults, eventually coming to regard her as a danger to the school and all who resided at the castle.[29]

James and his group of friends were constantly at war with Severus throughout their school years. Severus's memories, recorded in the Pensieve, suggested that he was an introverted and studious individual, whereas James was arrogant, popular and athletic. Immediately upon meeting him, James disliked Severus for expressing a desire to be in Slytherin. James's big crush on Lily, and Severus's close friendship and unrequited love for her also heightened the tension between the two.[6][7]

Severus noticed that Remus kept disappearing during the full moon and once followed him past the Whomping Willow (after being tipped off on how to do so by Sirius Black). This act could have cost Severus his life, as had it not been for James going after him to stop him when he learned of Sirius's plan, he might have found himself all on his own and caught off guard by a fully-fledged werewolf. As it was, however, James did reach Severus in time and managed to save him just before he got to the Shrieking Shack while Remus was in his wolf-form. Albus Dumbledore swore Severus to secrecy, but the true nature of Remus was clear to Severus.

One recorded memory in the Pensieve bore witness to James bullying him in the 1975–1976 school year, turning him upside-down to reveal his underwear in front of many students, including Lily. This action was proved to be very offensive and it increased the hatred between the two adolescents. In this accident, Lily came to Severus's defence, but this only made things worse: in a subsequent lashing out at James in an attempt to recover his lost dignity, Severus inadvertently called Lily a Mudblood. Lily refused to forgive him for it, even after his repeated apologies. This would forever be Severus's worst memory.[6]

By their seventh year, James appeared to have matured, and Lily agreed to start dating him, even though he never grew out of his hatred for Severus and continued hexing him behind Lily's back, despite being Head Boy — according to Sirius, Severus had always been a "special case" with James.[30]

There was also some overlap between his school career and that of a younger student by the name of Jacob, yet another rule-breaker Snape came to severely dislike. During the later part of his magical education, the school was plagued by several dangerous curses unleashed upon the school by Jacob after he tampered with the fabled Cursed Vaults, which resulted in the death and injury of several of his peers, although he suffered no permanent injury himself.

Half-Blood Prince "This book is the property of the Half Blood Prince." — The inside cover of the textbook[src]

Severus was a talented wizard even in his childhood. It was apparent through the notes and scribbles in his potions textbook that he made time during classes to invent curses, charms, and clever potion innovations, while simultaneously learning the required textbook lessons.[27][31]

Severus's potions textbook contained a few spells and curses which he was credited with inventing: Levicorpus, which grabbed the victim by the ankle and dangled him/her upside-down,[32] and Sectumsempra, which caused slashing bloody cuts (guided by the wand gestures of the caster, like a blade/sword) which bled extensively.[33] Levicorpus somehow escaped from Severus's secrecy, and became very popular around Hogwarts towards the end of his fifth year at school. Some other spells included Muffliato, which filled the ears of anyone nearby with an unidentifiable buzzing sound and another hex that caused toenails to grow at an unnaturally fast rate.[32]

Severus's book later fell into the hands of Harry Potter in September 1996. Harry used the Half-Blood Prince's tips and earned praise with that year's Potions master, Professor Slughorn. Harry considered the Half-Blood Prince to be a better teacher than Severus, unaware at that point that Severus was the Prince, much to Harry's later displeasure.[27]

The potions textbook has an inscription indicating it is Property of the Half-Blood Prince.[31] Hermione Granger's research revealed that Prince was the maiden name of Severus's mother and so the nickname was revealed to be a combination of his mother's maiden name and his blood status. Harry Potter also pointed out the similarities between Snape's nickname and the name Voldemort gave himself. This nickname was apparently a secret, as Remus did not remember it ever being used publicly by Severus.

First Wizarding War (1978–1981) As a Death Eater "The one with the power to vanquish the Dark Lord approaches… Born to those who have thrice defied him, born as the seventh month dies…." — The part of Sybil Trelawney's first prophecy that Snape overheard[src]

Severus Snape eventually joined the ranks of Lord Voldemort's Death Eaters. His actions as a Death Eater are largely unknown, though he quickly became an important Death Eater in Voldemort's inner circle. He was the spy responsible for informing Voldemort about the prophecy foretelling his downfall. In early 1980, Snape eavesdropped on an interview for Divination Professor Sybill Trelawney and Albus Dumbledore at the Hog's Head Inn.

In the course of the interview, Trelawney prophesied that at the end of July, a child would be born who would cause the destruction of Lord Voldemort (which prompted Dumbledore to hire her, partly for her own safety). At that time it was not clear who was meant by the prophecy. Two children of prominent wizarding families were born that year at the end of July: Harry Potter and Neville Longbottom.

Albus reported at the Wizengamot trial of Igor Karkaroff that Severus had come to him and explained that he had been the one to overhear the prophecy, and reported it to Voldemort. However, Snape did not hear the entire prophecy, as the Hog's Head's barman and Albus' brother, Aberforth, caught him eavesdropping and threw him out.

As a double agent Albus Dumbledore: "If you loved Lily Evans, if you truly loved her, then your way forward is clear. You know how and why she died. Make sure it was not in vain. Help me protect Lily's son." Severus Snape: "Very well. But never — never tell, Dumbledore! This must be between us! Swear it! I cannot bear... especially Potter's son..." — Snape promises to protect Harry after Lily's murder[src]

When Snape overheard the Prophecy, he promptly reported it to the Dark Lord, unaware that it concerned Lily. Once he realised Voldemort intended to kill Lily's son, Snape begged him to spare her, on account of his role in delivering the prophecy. He then turned to Albus Dumbledore for help. Dumbledore, initially cold due to Snape's Death Eater ties, accused him of only caring about Lily, not her husband or child. Snape pleaded with Dumbledore to protect Lily and her family, offering anything in return. After Lily's death, Snape dedicated himself to protecting Harry's life, on account of him being her son, and aiding in Voldemort's defeat. In fact, Snape's plea to Voldemort enabled Lily to sacrifice herself for Harry, which caused the curse to rebound, destroying Voldemort's body.

Despite Dumbledore's best efforts to protect the Potters, Voldemort was tipped off by Peter Pettigrew, one of James' best friends, a spy, and he found them anyway. After Lily's death, Snape was devastated and distraught to the point of wishing himself dead, but Dumbledore urged him to ensure Harry's safety out of respect for Lily's memory; Snape initially insisted the danger had been averted with Voldemort gone, only for Dumbledore to insist that he would return and everyone, particularly the boy, would be in danger when that happened. So Snape spent the rest of his life protecting her child, Harry Potter, who was often said to strongly resemble James. Distrusted for his past as a Death Eater by those on Albus Dumbledore's side, and hated by other Death Eaters for living as Dumbledore's stooge for ten years, Snape continued living on to complete Dumbledore's plan to protect Harry and defeat Voldemort.

Career at Hogwarts (1981–1995) "You are here to learn the subtle science and exact art of potion-making. As there is little foolish wand-waving here, many of you will hardly believe this is magic. I don't expect you will really understand the beauty of the softly simmering cauldron with its shimmering fumes, the delicate power of liquids that creep through human veins, bewitching the mind, ensnaring the senses... I can teach you how to bottle fame, brew glory, even put a stopper in death — if you aren't as big a bunch of dunderheads as I usually have to teach." — Snape teaching Potions at Hogwarts[src]

When Severus Snape began his teaching career at Hogwarts in 1981, taking up a teaching post around the same time as the threat posed by the rampaging curses that had terrorised the castle's residents were contained and the subsequent expulsion of his former peer, Jacob, for the rules he had broken in his quest for the Cursed Vaults and the fellow students who had been endangered in the process, he initially applied for the position of Defence Against the Dark Arts teacher, but was rejected multiple times.[34]

Many students were under the impression that this was because Dumbledore feared Snape might return to his old ways if allowed to teach his favourite subject, but in reality it was because Dumbledore was aware by that point that the job had been jinxed by Voldemort. Knowing that no Defence Against the Dark Arts teacher would last longer than a year, Dumbledore instead employed Snape in the position of Potions Master and Head of Slytherin House, following the retirement of veteran Potions Master Professor Horace Slughorn. Though it seemed rather uncommon for someone as young as Snape to be named a Head of House at Hogwarts, it is possible that Snape was the only Slytherin teacher left at the school, or that he was placed there to keep a watchful eye on the young Slytherins, who were frequently accused of (but not without reason) joining the Death Eaters.

Following Voldemort's fall, Snape never attempted to find his old master, having switched sides ever since Voldemort had targeted Lily and this allowed him to avoid time in Azkaban as Dumbledore staunchly defended him. He fabricated the fact that he believed Voldemort to be dead as an alibi for still loyal Death Eaters, but in truth, he and Dumbledore had discussed Voldemort and knew he would inevitably return, henceforth the most important reason why he applied as a teacher: to ensure from the shadows the safety of Harry Potter, who Lily had died protecting. This would bring him into conflict with fanatical Death Eaters like Bellatrix Lestrange later in life, but Snape was almost immediately forgiven by the reborn Voldemort, because he could provide him with thirteen years of information on Dumbledore and the Order of the Phoenix.

In the meantime and with Voldemort vanished, he focused on his teaching duties at Hogwarts. As a professor, Snape was a stickler for discipline, with little patience for foolishness, yet extremely effective in his job and well respected by the other professors. His deep understanding of potion brewing, as shown by his expert concoction of Wolfsbane Potion,[30][35] transformed the knowledge of potions from mere chemistry to an art.

He would accept students into his N.E.W.T. classes only if they had achieved an 'Outstanding' mark at their O.W.L. examination. He felt that anyone with a lower mark than that would lack the passion and the devotion to the complex and demanding subjects that would follow in the last two years of school. Though strict, Snape had an obvious bias for Slytherins, giving them undeserved rights over the others, while looking down on the other students somewhat unfairly. His interpersonal relations with students outside his own house were subpar at best. He would, on numerous occasions, bully students without any repercussions. Though, one might dispute if his disdain for Neville Longbottom was more about bullying or about the fact Voldemort had chosen to target the Potters over the Longbottoms, and if he'd picked the Longbottoms instead, Lily Potter would perhaps still be alive. He once threatened to poison Neville's pet toad, Trevor, or tell Neville how stupid he was. Once he even told Hermione Granger that her enlarged teeth were the same size as usual, neither of which were necessary behaviours.

Snape's role during this entire time was extremely sensitive and required master espionage and image-control skills. As he and Dumbledore anticipated that Voldemort would return eventually, and many of Snape's actions would be reported on by Death Eater spies or gained through torture and Legilimency, even if Snape's true mentality and intentions were inaccessible to Voldemort, he had to consider every decision and relationship carefully. He treated Harry Potter with maximal coldness and never missed an opportunity to cause him trouble, as any variation from this would have cast suspicion on him in Voldemort's eyes.

But in reality, he protected Harry on numerous occasions; he was happy enough to cause the boy, who resembled his father, Snape's hated rival from school days, humiliation and trouble, but never any actual harm or danger as he was still Lily's son. He also had to avoid becoming too aware of Voldemort's plans, so as to avoid being held responsible for allowing Harry and his friends to foil them. His actions during this period created no mistrust on the part of Voldemort, which allowed for Voldemort's ultimate downfall.

1984–1985 school year Argus Filch: "Is it true that the vaults are filled with gold and powerful prophecies and artefacts from before Hogwarts existed? And that's why that Jacob boy lost his mind trying to find them?" Severus Snape: "Don't worry about what's inside the vaults. Worry about keeping everyone out. Lock the door and keep it guarded." — Snape and Filch discusses the first sign that someone has tampered with the Cursed Vaults[src]

Closing in on the first half a decade of his tenure as an instructor at Hogwarts, Professor Snape was present at the Start-of-Term Feast of the 1984–1985 school year, during which he was introduced to the new first-years as the Head of Slytherin House during the Sorting Ceremony. He witnessed the sorting of, among others, the younger sibling of Jacob, who was Sorted into the same house as Jacob and of whom he became immediately suspicious.[36]

During the very first day of teaching the first years, he instructed the newcomers in the correct way in which to brew a Cure for Boils, during which he made no attempt at hiding his dislike for Jacob's cognate, and openly favoured Merula Snyde,[37] a student in his own house and whose parents had been among his own comrades during his time as a Death Eater, presumably both due to his bias towards his own house, as well as part of maintaining his cover as a future double agent. Throughout the year, he proceeded to teach this class, among other things, the Wiggenweld Potion,[38] the Herbicide Potion[39] and the Sleeping Draught.[40] Throughout the term, however, Professor Snape found himself reluctantly acknowledging the said student's talent.

At that time, there was unfinished business between Jacob's sibling and Merula Snyde, since Merula tried to attack Rowan Khanna, Ben Copper and Jacob's sibling; so both of them were trying to be prepared for the inescapable duel; as Jacob's sibling's prefect had told them, they needed to learn an offensive spell, an advantage charm, and a healing potion or charm. Both of them were looking forward to the Wiggenweld Potion and Snape's class. Snape's favourite student, Merula, asked him to teach the class the potion, though coincidentally Snape had already planned to teach it, as Rowan had notified Jacob's sibling earlier. When the class brewed their potions, Snape admired Jacob's sibling's potion skills, though he admired Merula's more.[38]

Sometime later, Snape and the school's Charms Master Filius Flitwick were made aware of how there were to be an unsanctioned duel between Jacob's sibling and Merula Snyde in the Clocktower Courtyard, arriving just in time to see the latter successfully deprive their opponent of her wand. Although Professor Filius Flitwick wanted to know who it was that cast the first spell, keeping in mind that Jacob's sibling had been instructed to only ever use the Disarming Charm defensively, Snape was largely dismissive of who started the fight.[41]

After subtly criticising his colleague, whom he correctly deduced were the one who had instructed said student in how to cast the Disarming Charm in the first place, he ordered both students to get cleaned up and meet up at the West Tower in order to receive punishment for their transgression.[41]

Upon reporting the incident to Albus Dumbledore, Snape asked for Jacob's sibling to be expelled, whom he regarded as a troublemaker just like their brother before them, a request the Headmaster rejected, and which he would soon thereafter lament about in the presence of both Jacob's sibling and Snyde. Although he docked twenty points from the former's house, he was interrupted by the caretaker of the day, Argus Filch, before he could do anything else. Upon being informed about an incident that had occurred that demanded his immediate attention that was related to the Cursed Vaults, Snape ordered both students to return to their common rooms.[41]

Accompanying the caretaker to a corridor on the fifth floor, Mr Filch explained that he and his pet cat, Mrs Norris, had discovered how cursed ice had appeared in one of the rooms there. Immediately recognising this as one of the curses unleashed when someone had tampered with the Cursed Vaults, Snape immediately ordered Filch to lock the door and stand guard to prevent students from getting inside, before he left to inform the Headmaster. In the aftermath of this discovery, the faculty successfully managed to keep it from spreading any further and securely sealed up the room afterwards, although he was unaware the two students he had just left had followed them and overheard portions of his conversation with Filch and resolved to break into the room in order to look for clues regarding the whereabouts of the vaults.[42]

During the Herbicide Potion lesson, Merula made a mistake, and Jacob's sibling helped her to fix it. Unbelievably, when Snape understood it, he awarded Jacob's sibling with 10 points.[39]

Throughout the rest of the year, he presumably continued to keep a sharp eye on the students, especially Jacob's sibling, and do everything he could to keep the discovery from the student body, in which he was ultimately unsuccessful.[43]

Also he wanted to harvest the fairy wings for his potion ingredients. Rubeus Hagrid asked Jacob's sibling to move fairies to another place, so it happens to be a quest for them to save the fairies' wings. Jacob's sibling set out to move the fairies, though a fairy had gone to the Potions Classroom. Penny Haywood went to the classroom in order to help Jacob's sibling and the fairy as well. They thought of Jacob's sibling distracting Snape while Penny tried to make the fairy co-operate, while Snape believed she was looking for her favourite quill that her mother had given her. It is possible that Jacob's sibling distracted him with asking about Bottling Fame, or his hair, or about his well-being.[44]

At the Hallowe'en feast, Jacob's sibling needed some Aconite for the Wolfsbane Potion in order to help the werewolf Chiara Lobosca. Rowan Khanna distracted Snape to allow Jacob's sibling to steal from his store of ingredients.[45]

1985–1986 school year "I mentioned Harry Potter in Potions, and Snape threw a jar of pickled animal parts at me." — An unidentified first-year[src]

Around the beginning of the year, Snape assisted Professor McGonagall with using the Fire-Making Spell to free Ben Copper from the cursed ice. At some other point early on in the year, Snape became livid when a first-year mentioned Harry Potter in class, and hurled a jar of pickled animal parts at him.[46] During the Teacher Appreciation Celebration that year, Snape was interviewed by Penny Haywood.[47]

After these events, Snape searched Jacob's sibling's dormitory and found some potion ingredients that were useful against the Cursed Vaults, so he asked them in the classroom to explain it in order to defend themselves, though it was revealed that the evidence was a plot carried out by Merula.[48]

1986–1987 school year HM JS Finds A Black Quill Jacob's sibling finding a transfigured note

Snape continued his job as Potions Master at Hogwarts, and tried to prevent students' interference in the Cursed Vaults. He ordered Argus Filch to retrieve Jacob's note, which was an untransfigured black quill, from Jacob's sibling.[49]

Jacob's sibling stole the black quill, and with the help of Tulip Karasu, became one step closer to the third Cursed Vault. Tulip also helped them find their brother's corridor at Hogwarts, although it was protected with a two-lock padlock and an Anti-Alohomora Charm. Since Tulip had the key to one of the locks, and the other one was in the possession of her former friend, Merula Snyde, they took the key from her after letting off a Dungbomb. When they opened the door, Jacob's sibling confronted a Boggart in the form of Lord Voldemort. In time, Severus Snape found them and warned Jacob's sibling that they had to let go of the Cursed Vaults unless they wanted to share Jacob's fate - expulsion.[50]

During Jacob's sibling's career advice to William Weasley, they took him to Professor Snape's classroom, in order to seek advice about potioneering. Professor Snape asked them to brew an original potion, so he'd be able to make his decision according to their performance. It's unknown what Jacob's sibling chose to brew, though it was either a Contortion Potion, a Screaming Potion, or a Stamina Potion. After the potion was brewed, at least one of them drank it on Snape's order, as "drinking the potion is the only way to measure your success" according to Snape. The poorly brewed potion made the drinker sick, thus Snape questioned Bill's potioneering skills.[51]

1987–1988 school year "I don't believe she's working alone, and I believe at least one of her co-conspirators is a student in Slytherin." — Snape on Rakepick's investigation for the Cursed Vaults[src] This year began with an old untrustworthy enemy of Severus, and also an old classmate of his, Patricia Rakepick, a Curse-Breaker from Gringotts Wizarding Bank, arriving at Hogwarts, invited by Albus Dumbledore.[52]

Jacob's sibling became to suspect Madam Rakepick, therefore they accosted Snape, in one of the Potions study sessions, and asked him about the new Curse-Breaker. After the session, he told them about Rakepick and the fact that she couldn't be trusted and how dangerous she was. Though he called it unwise to question Dumbledore's judgement without substantial evidence, as the Headmaster trusted Rakepick.[28]

A little while later, when Jacob's sibling was planning to fly to the next Cursed Vault in the Forbidden Forest, Professor Snape broke Jacob's sibling's borrowed broomstick and sought an unexpected help from Jacob's sibling with revealing Rakepick's true intention.[53] In addition to Snape's unexpected request, he revealed an unexpected fact, telling them that Rakepick had been monitoring and spying Jacob's sibling ever since she arrived at Hogwarts. Thus he asked them to spy on her.[29]

Jacob's sibling spied on her many times while taking orders from Snape, although Snape admitted them spying on her was totally useless, since she said whatever she wanted Severus to know and also she knew they were spying. Nevertheless, he warned them not to tell any of this to anyone.[29]

He also gave Jacob's sibling a Garrotting Gas[29] that would later save their and Merula's life from Rakepick's Cruciatus Curse in the Buried Vault.[54]

At the end of the year, Madam Rakepick won the Defence Against the Dark Arts Professor title against Snape.[55]

1988–1989 school year

This year began while Snape's hatred of Rakepick was more intense than ever.[55]

During Jacob's sibling's search for the fifth Cursed Vault and the Marauder's Map, he faced Peeves multiple times. One of these times they were searching for a friend of Jacob's, Duncan Ashe. Peeves mentioned that he, Duncan Ashe, hated two things, potions and Jacob, though he loathed Jacob more than potions, so Jacob's sibling went to Snape, in order to gather information about Ashe. Snape revealed to them that he never liked the Marauders and somehow disappointed them.[56] In addition of their searches, Penny Haywood, one of the victim's sister, was very concerned about the Cursed Vaults that she would not do what she was gifted in - potioneering. Therefore, Severus, who though she would have a good career in potioneering, although due to what happened to her sister Beatrice, his mind had changed and somehow he was disappointed. A fair warning from him to Jacob's sibling would make them think about Miss Haywood. And this would help Haywood and Jacob's sibling control themselves and try to find a way to break the last curse and free both Jacob and Beatrice.[57]

Though, on Dumbledore's order, he was willing to help Jacob's sibling with mastering Legilimency and Occlumency. Thus, Jacob's sibling was taught by Severus Snape, a decent Legilimens and Occlumens. Severus Snape asked them to defend themselves against him casting Legilimens on Jacob's sibling, and he also revealed some of their secrets. And he believed that Jacob's sibling had not even tried to not let Severus get into his thoughts, and thought it settled the fact that Jacob gave them visions from a far distance. He also demanded them, twice, to cast the spell on him, and this proved to Jacob's sibling the power of Occlumency.[58]

Later, while inventing the Star Shower Spell, Jacob's sibling went to Merula and Professor Snape. While Professor Flitwick approved of their spell, it was later revealed that this was not the Star Shower Charm but Star Shimming Charm. Professor Snape perceived the issue and helped Jacob's sibling fix this.[59]

Snape was also seen with Poppy Pomfrey and Albus Dumbledore while coming in order to take see what has happened to Merula Snyde after Rakepick's betrayal in the Buried Vault.[60]

Madam Rakepick was seen while using Lacarnum Inflamari on Snape's cloak.[61]

During Jacob's sibling's mental examination on Scabbers for his odd behaviour, Percy Weasley, Charles Weasley, and Jacob's sibling met each other multiple times at the Great Hall. Because they had Scabbers, Snape warned them that a rat must not be in the Great Hall. The second time, when Jacob's sibling's rat was also present, and while there was a fight between Charles and Percy, Snape asked them "kindly" to discuss their "nothing" somewhere else without disturbing anyone; though because of his perfect sense of smell, he smelled some rats, though both of the rats escaped; when Snape left, the students searched for Scabbers and Jacob's sibling's rat, and after they found them, they continued their research. Their research ended up with Silvanus Kettleburn suggesting borrowing Rat Tonic from Professor Snape in order to calm the rat from the anxiety he had because of an unknown source of fear. After convincing Snape, he helped Charles and Jacob's sibling with instructions and ingredients, and they brewed the potion. Percy arrived with Scabbers, and with the presence of Snape, Jacob's sibling finally understood that what the rat feared was the professor, unbeknownst to them his lifelong enemy.[62]

1989–1990 school year This school year began with Snape's old enemy, Madam Rakepick, being fired after her betrayal.[63]

This year at Hogwarts was also as dangerous as the other years, or perhaps more so. Not so later from the start of the year, Beatrice Haywood found a Petrified student because of the statue curse. Thus, she notified the Potions Master, Severus Snape, and then they notified Jacob's sibling and their examination result was that the Petrified student had some texture, the same as the Merpeople Trident that he found in the Buried Vault.[64] Also Professor Snape was seen while he was talking about the statue curse with Headmaster Dumbledore.[65]

Madam Rakepick used to store so many dark and cursed items in her classroom, after her betrayal and expulsion, Argus Filch, collected her cursed items and Severus Snape took the items from the caretaker in order to break their curses. While Jacob's sibling was searching for the items, they and Merula Snyde found Professor Snape while brewing Veritaserum; and he told them that he was unable to break the curses, therefor he gave them to the only one who could break the curses - Headmaster Dumbledore.[66]

Severus Snape, once had been ordered to retrieve Jacob's sibling when Madam Poppy Pomfrey was Petrified with the Statue Curse, and unfortunately, it meant that there was no one to take care of the Petrified students or the students that had any kind of illness. So after an announcement taken by the Headmaster, students had to visit Snape or Sprout, if they had any kind of symptom of illness.[67] He most likely he taught the students the Cough Potion after her Petrification, because of Dumbledore's announcement.[68]

Snape was introduced to the Brazilian exchange student Alanza Alves by Jacob's sibling in his classroom that school year, whom would be joining his sixth-year Potions class. Snape was in the midst of a conversation in his classroom with Argus Filch and Madam Pince, where he informed them that Ashwinder eggs and Occamy eggshells had gone missing from his stores (which Beatrice Haywood had stolen to brew Felix Felicis with). Snape was also rather displeased to be informed by Alanza that her potions had a tendency to explode.[69]

1990–1991 school year During this year, Jacob's sibling requested Snape for some Floo powder, which they needed to enter the British Ministry of Magic via the Floo Network for their work experience programme there. Snape was at the time engaged in a one-sided conversation with Arif Sikander in his classroom, the Muggle Studies professor, who was talking to him about Muggle chemistry, which Snape had no time for. Snape gave them the powder and told them and Sikander to leave, rudely telling them he could stand either of them.[70]

Snape also taught seventh-years how to brew the Wolfsbane Potion for the Department for the Regulation and Control of Magical Creatures when no alternative presented itself, as part of their work experience task of helping the Ministry locate a fugitive werewolf.[71]

Snape examined the hair care potion Xeep's Luscious Locks Solution when it became clear its users were suffering from memory loss, for Jacob's sibling and Penny Haywood on their Ministry business. He discovered the potion contained potent memory loss powers, and that it contained the Forgetfulness Potion as its base, with lavender and valerian as its ingredients. He also agreed to help then develop the counter-serum for it, once he had determined all of its ingredients.[72] He later helped Penny and Jacob's sibling complete the counter-serum.[73]

Snape also analysed a pitcher that contained Pumpkin juice for Jacob's sibling to see if contained remnants of the Alihotsy Draught, which could explain the laughing curse affecting St Mungo's, but Snape found no traces of the potion, much to their displeasure.[74]

1991–1992 school year Severus Snape: "You don't want me as your enemy, Quirrell." Quirinus Quirrell: "I-I don't know what you —" Severus Snape: "You know perfectly well what I mean." — A warning after Quirrell attempted to seize the Philosopher's Stone[src]

In 1991, Nicolas Flamel, a famous alchemist and friend of Albus Dumbledore, had the Philosopher's Stone that was keeping him alive moved from his safe in Gringotts to Hogwarts for safekeeping. Snape contributed to the defences set up around the magical artefact by adding a Potion riddle as one of the obstacles, and the only obstacle that used logic as a key factor instead of magic.[75]

At the same time, Harry Potter became a student in Snape's classes, and the two of them detested each other almost immediately. Harry's resemblance to his father and his acquired 'celebrity' status brought the worst out of Snape from their very first Potions lesson.[9] Although Snape had pledged an oath to Dumbledore that he would protect Harry, such an oath did not stand in the way of Snape's bias to Slytherin House, nor did it mean Harry was to get any special treatment in academics (in fact, he ended up giving Harry the exact opposite).[7]

Throughout the year as part of his promise to Dumbledore, Snape did everything he could to prevent Defence Against the Dark Arts Professor Quirinus Quirrell from helping Lord Voldemort obtain the Philosopher's Stone, having seen him as what he was and at least knew he was helping Voldemort, if not also being aware of Voldemort possessing Quirrell. By 31 October, the turbaned Professor, sure enough, made his first move by letting a Mountain troll into Hogwarts Castle as a diversion. Snape took this chance to stop him from sneaking into the restricted third-floor corridor where the Stone was being hidden in the midst of the chaotic event, only to get bitten in the leg by the corridor's three-headed guard dog, Fluffy.[76][77]

When Quirrell made his first attempt on Harry's life by jinxing his new broomstick during the boy's first Quidditch game, Snape intervened again by performing a counter-curse to prevent Harry from being hurled off. Unfortunately, Hermione Granger observed the crowd through binoculars to figure out who was performing the jinx and caught Snape discreetly uttering the counter-curse incantation, but erroneously thought he was performing the actual curse. So she ran to his stand and set fire to his robes in order to distract him and make him stop, and luckily for Snape, she accidentally knocked Quirrell over during her hurry back to the Gryffindor stands, causing him to break the eye contact necessary for performing his spell correctly.

For the next match, Snape insisted on refereeing to make sure it did not happen again. This did not come across well to the other teachers, who believed that he was just trying to injure the Gryffindor Quidditch team's chances of winning.[78]

Snape intensely confronted Quirrell in the Forbidden Forest on the night after the match, demanding to know why he was after the Philosopher's Stone. Unbeknownst to them both, Harry was watching the entire argument from the treetops, having followed his Potions teacher into the forest on his broomstick after passing him at the school Quidditch shed. But because the boy suspected Snape of plotting to steal the stone and of attempting to kill him, it seemed to him that the Potions professor was trying to intimidate Quirrell into handing over information regarding the artefact.[79]

Harry, Ron Weasley and Hermione unjustly tried to be supportive and encouraging to Quirrell whenever possible by telling people off for laughing at his stutter, smiling at him encouragingly whenever they passed him or arguing with Snape.[80]

Snape was present at the Leaving Feast that year. He was initially very pleased to see that Slytherin had won the House Cup again, but was forced to shake McGonagall's hand with a forced smile after Dumbledore's additional house points to Harry, Ron, Hermione and Neville Longbottom meant that Gryffindor had won instead.[77]

1992–1993 school year Harry Potter: "Maybe he's left, because he missed out on the Defence Against the Dark Arts job again!" Ron Weasley: "Or he might have been sacked! I mean, everyone hates him —" Severus Snape: "Or maybe he's waiting to hear why you two didn't arrive on the school train." — Professor Snape confronting Harry and Ron after they arrived via a flying car[src]

During the beginning of the school year in 1992, Snape learned from the Evening Prophet that Muggles spotted Harry and Ron travelling to Hogwarts in the Flying Ford Anglia, instead of on the Hogwarts Express. Knowing the severity of their deeds could very well cause them to be expelled, which would put Harry in great danger as he would lose Dumbledore's protection, Snape took matters into his hand and confronted them when they had landed, where he severely berated them for their breach of one of the most sacred laws of their world and pretended to call upon Professors Dumbledore and Minerva McGonagall to make them solve this situation. It was as Snape wanted: Dumbledore ensured they would not be expelled and Minerva punished them instead by giving them a warning and separate detentions.[81]