How Snape helped Harry while making his life miserable

Snape’s first rescue gets him blamed for the attack. During Harry’s first Quidditch match, Hermione sees Snape muttering as Harry’s broom tries to throw him off. She sets Snape’s robes alight to stop him.

Professor Quirrell (Ian Hart) later admits that Snape was casting the counter-curse keeping Harry alive. He also says that the fire broke his own eye contact with Harry, ending the jinx. Hermione’s accusation is wrong even though her intervention helps.

Snape is pursuing the threat Harry has mistaken him for. Snape confronts Quirrell in a Hogwarts corridor at night and presses him about his loyalties. Harry, hidden under his Invisibility Cloak, takes this as evidence that Snape wants the Sorcerer’s Stone.

Quirrell is the one serving Lord Voldemort (Ian Hart, voice). Snape’s hostility towards Quirrell is part of his effort to stop him, while the limp Harry notices comes from the three-headed dog guarding the Stone.

Snape’s contempt for a fraud comes with a useful lesson. At the Duelling Club, Snape uses Expelliarmus to send Gilderoy Lockhart (Kenneth Branagh) flying. Harry sees a working disarming spell from a teacher who spends much of their time together belittling him.

Hermione asks, “Do you think he’s all right?” Ron Weasley (Rupert Grint) answers, “Who cares?” Harry later uses the same spell against Lord Voldemort (Ralph Fiennes), including in their final duel.

Snape is the strict parent here. Covering a lesson for Remus Lupin (David Thewlis), Snape asks about the difference between a werewolf and an Animagus, a witch or wizard who can turn into an animal. Hermione supplies the answer after being told not to speak out of turn.

He calls her an “insufferable know-it-all”; Ron says he has a point. Snape takes five points from Gryffindor. He is doing a service by insisting that Hermione follow the classroom rules even when she knows the answer.

Snape protects the students even after Harry has attacked him. In the Shrieking Shack, Harry alone casts Expelliarmus at Snape, knocking him backwards and leaving him unconscious.

Later, outside on the Hogwarts grounds, Lupin transforms into a werewolf. Snape steps in front of Harry, Hermione and Ron and spreads his arms across them. His anger at Harry does not stop him putting himself between the three of them and the werewolf.

Snape owes Harry a correction after accusing the wrong person of stealing Polyjuice ingredients. Snape blames Harry and shuts the door in his face. The missing ingredients have instead helped an impostor maintain his disguise.

When the false Alastor Moody (Brendan Gleeson) takes Harry to his office after the tournament, Snape arrives with Albus Dumbledore (Michael Gambon) and Minerva McGonagall (Maggie Smith). Snape supplies Veritaserum, the truth potion Dumbledore uses to question him. As Barty Crouch Jr (David Tennant) is exposed, the look between Harry and Snape brings that accusation back: Harry was not the thief.

Snape helps Harry practise defending his mind, even though neither can put their resentment aside. Snape teaches Harry Occlumency because Voldemort can reach into Harry’s thoughts. The help lies in making Harry resist an intrusion.

Harry uses Protego to turn Snape’s Legilimens spell back on him. He sees James Potter (Robbie Jarvis) and Sirius Black (James Walters) among the boys humiliating the schoolboy Snape (Alec Hopkins). Snape ends the lesson with “Get out”: Harry has learnt something about resisting him, and something about why this teacher hates his father.

Snape obstructs Dolores Umbridge (Imelda Staunton) while keeping his answer unhelpful enough to pass as indifference. When Umbridge demands Veritaserum for Harry, Snape says she has exhausted his supply, using the last of it on Cho Chang (Katie Leung). That also tells the students their friend was forced to reveal the group’s secret.

Harry then warns that Padfoot, the code name he uses for Sirius Black (Gary Oldman), is in danger. Asked to explain the warning, Snape says, “No idea.” He leaves Umbridge without the explanation Harry has tried to pass him.

Snape helps Harry through a book before Harry knows whose advice he is following. Harry uses annotations in a second-hand Potions textbook to outperform his classmates and win Felix Felicis, a potion that gives its drinker good luck, from Horace Slughorn (Jim Broadbent).

The writer is Snape, the Half-Blood Prince. Harry uses the prize while obtaining Slughorn’s real memory about Horcruxes, the objects in which Voldemort hides parts of his soul. The book’s help reaches Harry by chance, and Harry’s trust in its unnamed author also leads him towards a dangerous spell.

Snape saves the life of Draco Malfoy (Tom Felton) and prevents Harry’s mistake from becoming a killing. Harry uses Sectumsempra from the annotated book without knowing what it does, leaving Draco bleeding on the bathroom floor.

Snape kneels beside Draco and heals the wounds with a counter spell. His counter spell keeps Draco alive, sparing Harry the consequences of killing another student. The same teacher whose writing supplied the spell has to repair the harm Harry causes with it.

Snape uses loyalty to Voldemort as a reason to stop another attack on Harry. During the escape from Hogwarts, Bellatrix Lestrange (Helena Bonham Carter) curses Harry backwards. Snape intervenes: “No! He belongs to the Dark Lord!”

Harry has just watched Snape kill Dumbledore, so he has no reason to hear protection in that command. Snape nevertheless stops Bellatrix continuing against the boy Voldemort wants to kill himself.

Snape’s apparent betrayal comes from an agreement with the man he kills. In the Pensieve memories, Snape gives Dumbledore a potion to contain the curse in his injured hand for the time being. He warns that it will spread, estimating “Maybe a year.”

Dumbledore tells him, “You must be the one to kill me,” and explains that this will secure Voldemort’s complete trust. Killing him on the Astronomy Tower is part of that agreement. Harry sees a murder without knowing that the two men have arranged it.

Snape’s help becomes recognisable only after Harry learns whose Patronus he has followed. Harry follows a silver doe to a frozen pool containing the Sword of Gryffindor. Ron rescues him from the water and uses the sword to destroy the locket Horcrux.

Harry asks Ron whether the doe was his. Ron thought it was Harry’s; Harry replies, “My Patronus is a stag.” The later memories show that Snape has a doe Patronus, which identifies him as Harry’s unseen guide to the sword.

Snape’s final help tells Harry why he was protected and what he must now face. As Snape dies, he gives Harry his memories. Harry takes them to the Pensieve and sees Snape’s promise to Dumbledore to protect the son of Lily Potter (Geraldine Somerville).

He also learns that he carries part of Voldemort’s soul: Harry himself is a Horcrux, and Voldemort must kill that part. Snape’s love for Lily explains why he protects Harry despite his contempt. The contempt was still contempt, and the task ahead of Harry is still his to face.