If there’s one thing that J.K. Rowling excels at, it’s creating complex characters who straddle the boundaries of right and wrong. One of the most glaring examples of this is Potions Master and Head of Slytherin house, Severus Snape. In Rowling’s own words, “Snape is all grey. You can’t make him a saint: he was vindictive & bullying. You can’t make him a devil: he died to save the wizarding world.” Nevertheless, the great Snape debate rages on as fans continue to judge him on both his actions and unpleasant demeanor.

Love him or hate him, if it wasn’t for Severus Snape, Harry Potter’s story would have turned out a lot differently. Snape risked his life on a daily basis to ensure Voldemort’s downfall and Harry’s ultimate sacrifice, all in honor of his one true love. Not only was Snape a master double agent, he fooled the most powerful dark wizard of all time. Only an extremely skilled Legilimens could have pulled that off, especially right under Voldemort’s lack of a nose. Although J.K. Rowling revealed Snape’s deepest secret in Harry Potter and the Deathly Hallows, there are still some things you may not know about Hogwarts’ Potions professor. Here are 15 Things You Didn’t Know About Severus Snape.

15. He was the only Death Eater who could conjure a Patronus

Severus Snape Doe Patronus in Harry Potter and the Deathly Hallows Part 1 Harry Potter: 15 Things You Didnt Know About Severus Snape

A product of an unstable and possibly abusive family, and frequent target of bullying at Hogwarts, Snape took a liking to the Dark Arts at an early age. This immediately put him at odds with his best friend and object of affection, Lily Evans, who was very much against the use of dark magic. Nevertheless, Snape’s desire for revenge and need to impress Lily became stronger when James Potter began vying for her attention as well. At the start of the First Wizarding War, he joined the Death Eaters along with other Slytherins from his year.

Dementors and other dark magical creatures were aligned with Lord Voldemort during both Wizarding Wars. They were all drawn to the darkness and negativity surrounding him. What need, then, did a Death Eater have of producing a Patronus– a powerful light charm that was the complete antithesis of what they stood for?

Unlike his Death Eater comrades, however, Snape’s immense capacity for love was stronger than his pull toward the darkness. His memories and feelings around growing up with Lily brought Snape his only true happiness and as such he was able to produce a full Patronus.

14. He invented a number of spells and curses while still a student

Sectum Sempra Curse in Severus Snapes Advanced Potion Making Book Harry Potter: 15 Things You Didnt Know About Severus Snape

Most Harry Potter fans are aware of one of Snape’s homemade curses, Sectumsempra. In Harry Potter and the Half-Blood Prince, Harry comes to possess Snape’s Advanced Potion Making textbook where he has written the curse in the margins. Harry then uses it against Draco Malfoy and even tries to use it against Snape after he kills Dumbledore. However, there were a number of other spells and curses invented by Snape as a student.

Since Snape invented Sectumsempra, it seemed only natural that he’d also create a counter-spell to reverse its effects. Vulnera Sanentur heals the wounds created by Sectumsempra’s violent slashes. He was also the creator of the Muffliato Charm, which created a buzzing sound in someone’s ear so they couldn’t eavesdrop.

Owing to the fact he was bullied all the time, he also created Langlock, which glued a person’s tongue to the top of their mouth, rendering them speechless. Levicorpus was also likely a product of his bullying and is seen in the film version of Harry Potter and the Order of the Phoenix. During his Occlumency lesson, Harry becomes privy to Snape’s worst memory where James Potter uses the spell to taunt him.