But that’s exactly what he is. For six of the seven Harry Potter books Severus Snape is the head of the Slytherins, a group of students known for their cunning and deceitful ways. Slytherin is also known as the one house at Hogwarts most responsible for churning out dark wizards. That’s not surprising, really, given that they prize power more than anything else, and that Snape regularly encourages his students to do less-than-scrupulous things to get their house ahead. He also has no problems penalizing other houses while giving his an unfair advantage.

Snape doesn’t remain head of the house forever, though - once he’s forced to flee, after killing Albus Dumbledore, he loses the spot to a former head turned teacher, Horace Slughorn.

Snape takes on a more prestigious role soon after his flight, however - that of head of Hogwarts, appointed as such by Lord Voldemort.

The truth is, like all other things, finally revealed in the final book. Until then, though, it seems a mystery. Why does Dumbledore show such implicit trust for Snape? Snape, a man who’s a former death eater and who seems poised to betray his allies at every turn? Snape, who got Harry Potter eyed by the dark lord Voldemort in the first place? And why in god’s name would anybody trust Snape given that Snape actually kills Dumbledore?

In the end it actually boils down to Snape’s love of Harry’s mother that keeps him honest in Dumbledore’s eyes. The older wizard knows that Snape won’t Harry, and will indeed give his life to defend the boy, because of his love for Lily Potter. And as it turns out Dumbledore was already on his way out from a curse administered by Voldemort - in other words, Snape just eased his pain and helped progress Dumbledore’s plans.

Read the last book if you haven’t. You’ll learn there’s a lot more to Snape than meets the eye - not to mention the normally benevolent Dumbledore.

Harry’s position towards Snape is simple to read: he hates the man. Ever since his earliest days at Hogwarts where Snape has shown his utmost dislike for the Harry, Harry has held a special place in himself for Snape - that is, as a little, infuriating knot at the back of his brain. but how does Snape feel towards Harry?

That answer is a bit more complex than the books initially let on. At first it seems as though Snape dislikes Harry simply because Harry’s famous. He’s gotten where he is on his name alone and nothing else. He despises Harry’s apparent lack of wizarding skill - in potions, anyway, which is Snape’s forte - and berates the boy more than any other student for messing up.

But it goes deeper than that. As the books progress readers learn that much of Snape’s hatred comes from a hatred of Harry’s father, whom Harry resembles vividly. James Potter spent much of his time at Hogwarts making life miserable for Snape, and Snape never forgave the elder Potter for that. Hence he never gives Harry a chance to make a name for himself.

But it’s even more complicated than that, as Snape holds a brilliant flame inside him for Harry’s mother Lily. He loved her since they were children, and stayed loyal to her memory throughout the years. Hence, he is always ready to defend her child whenever he can - and that loyalty holds true at the end of the final book, where readers learn that Snape is not a traitor but rather one of Harry’s staunchest allies.

First, will Harry Potter die in the last book?

And, second, is Severus Snape a friend or a foe?

Both questions have been answered by now. But the topic of Severus Snape’s loyalties were probably of greater concern to a wider audience. Snape is such a deliciously unlikeable character that you can’t help but like him. And Alan Rickman’s portrayal of the grease-headed Hogwarts teacher only deepened his fanbase.

But it’s a good question, and was for a very long time. Is Snape a good guy? Or do his loyalties ultimately lie with Lord Voldemort? There’s a lot of evidence leaning both ways. He helps Potter and his friends quite a few times in the books and does a lot of good.

But he’s also a fairly repulsive person personality-wise, and he has an obvious detestation for all things Potter. Plus he also does something in the sixth book that casts a lot of doubt on his motives.

So which is he?

You’ll have to read to find out.