Despite his attraction to the Dark Arts and Voldemort's ideology of wizard supremacy, Snape's love for Muggle-born Lily Evans, Harry's mother, eventually compelled him to defect from the Death Eaters.

In any case, even after Quirrell's true role is revealed, Harry retains feelings of suspicion and resentment towards Snape, and their relationship remains tense.

Snape has a minor role in Harry Potter and the Chamber of Secrets, where he helps Gilderoy Lockhart oversee Hogwarts' short-lived Duelling Club,[25] but he has little interaction with the main plot.

[33] The sessions mainly consist in Snape forcibly reading Harry's mind to teach him to defend himself, but are made difficult by their mutual hostility.

He sees the memory of Snape being bullied by James and Sirius, and of calling Harry's mother Lily a Mudblood (a highly offensive term).

Towards the end of the novel, Dolores Umbridge – the school's politically appointed headmistress – captures Harry and interrogates him about Dumbledore's whereabouts.

She sends for Snape, demanding that he provide the magical truth serum Veritaserum in order to force Harry to reveal any information he may be hiding.

Snape then carries Harry's cryptic warning about Sirius' capture to the other Order members, allowing them to come to the rescue in the Department of Mysteries.

In the second chapter of Harry Potter and the Half-Blood Prince, Bellatrix Lestrange and Narcissa Malfoy visit Snape at his home in Spinner's End.

Harry finds marginalia, including a variety of hexes and jinxes seemingly invented by an unknown student, and substantial improvements to the book's standard potion-making instructions.

[44] The dying Snape releases a cloud of memories and tells Harry, who has watched the entire scene from a hidden spot, to take and view them.

Snape's knowledge of the Dark Arts enabled him to slow the spread of the curse from Dumbledore's hand through his body, but he would have died within a year.

[42] Rowling noted in an interview that because Snape abandoned his post before dying or officially retiring, a portrait of him does not immediately appear in the Headmaster's office following his death.

She adds, however, that she would like to think Harry made Snape's true loyalty and heroism known in the Wizarding world, and that he lobbied to ensure that a portrait be installed in the office.

In the play, Draco Malfoy's son Scorpius finds himself in an alternate timeline in which Voldemort won the Battle of Hogwarts, killed Harry, and instituted a reign of terror.

Snape then reveals that he, together with the fugitive Ron and Hermione Granger, maintain the last remnants of Dumbledore's Army – still waging hopeless resistance against the all-powerful Voldemort.

[51] When the directors of the films would ask him why he was doing a scene a certain way or delivering a line in a specific manner, Rickman would simply reply that he knew something they didn't.

[55] In 2011, Empire magazine published an open letter from Rickman to J.K. Rowling, ruminating on the ten years of working on the Potter films and thanking her for telling the story.

In the final film, Harry Potter and the Deathly Hallows – Part 2, the younger Snape, perhaps ten or eleven, is played by Benedict Clarke.

[60] The youthful Snape had a "stringy, pallid look", being "round-shouldered yet angular", having a "twitchy" walk "that recalled a spider" and "long oily hair that jumped about his face".

[27] In the chapter illustrations by Mary GrandPré in the American editions of The Prisoner of Azkaban, The Order of the Phoenix, and The Half-Blood Prince, Snape is depicted with a moustache and goatee, long black hair, and a receding hairline.

[3] Snape is a talented duellist, able to hold off by himself (if only briefly) a group of three Hogwarts professors that included former duelling champion Filius Flitwick.

[65] Snape's true loyalty was one of the most significant questions in the series up until the end of the final instalment, Harry Potter and the Deathly Hallows.

Curiously, the same thing appears to happen in the opposite side, when we see how Bellatrix Lestrange mistrust Snape and only the word of Voldemort seems to protect him from the suspicions of the other death-eaters.

[8] Joyce Millman suggests in her essay "To Sir with Love" in the book Mapping the World of Harry Potter, that Snape is derived from a tradition of Byronic heroes such as Wuthering Heights' Heathcliff.

The final revelation of Snape's loyalty in Harry Potter and the Deathly Hallows was viewed positively by fans and critics alike.

Daniel Radcliffe, who portrays Harry Potter in the movie series, expressed his delight, saying he was pleased to see that his theory that Snape would end up being a sort of tragic hero came through.

He is a starring character in Neil Cicierega's online Potter Puppet Pals parodies, and has a centric episode titled Bothering Snape.

Comic Relief released a story called Harry Potter and the Secret Chamberpot of Azerbaijan, in which Snape is played by Jeremy Irons.

In a sketch comedy named "Cooking With..." on Australian TV series The Wedge, Snape is played by Anthony Ahern, and catches Harry and Hermione making love.