Lily Evans and the Half-Blood Prince: The Real Secret Behind the Potion-Making Textbook
In Harry’s sixth year at Hogwarts, Snape reveals that he is the Half-Blood Prince, the person who wrote the textbook instructions that Harry has been enthusiastically following. Harry thinks this is the full story, but he doesn’t understand that Snape has a whole host of secrets he’s still hiding from Harry, most relating to Lily Evans.
“Shouldn’t have left his old book in the bottom of that cupboard, should he?” Harry says about Snape, which is a more revealing question than Harry might think (HBP 638). Harry’s right: Snape shouldn’t have left this particular textbook in a place where his students could find it, and he’s too smart to make a mistake like that. He is not the kind of teacher who would look kindly on his students using shortcuts to get ahead in a subject, which suggests that, potentially, there is another explanation for the book’s location.
So who put the Potions book there if it wasn’t Snape? My theory is that it was Lily Evans. Lily is all over the sixth book in subtle ways, especially through Slughorn mentioning multiple times that Lily was “a dab hand at Potions” and comparing Harry’s newfound brilliance to his mother’s abilities (HBP 191). The sixth book is Snape’s book; therefore, the way Slughorn’s comments tie the Half-Blood Prince’s book to Lily cannot be purely coincidental.
This is how I imagine the story to go: Snape and Lily are already friends by the time they arrive at school together. Both are skilled in all their classes, but Potions is the only class that Gryffindors and Slytherins have together, so the two sit at the same cauldron and feed off each other’s curiosity and intensity. Lily has the instinct that Slughorn mentions, whereas Snape is more methodical in his experimentation (HBP 319). By their fifth year, Slughorn has become so impressed with the pair of them that he invites them to skip straight to his sixth-year Potions class, and Snape’s mother lends him her used copy of Advanced Potion-Making.
How do I know that Snape took this class a year early? In “Snape’s Worst Memory,” James uses the Levicorpus spell that Snape invented, and Lupin says, “There were a few months in my fifth year when you couldn’t move for being hoisted into the air by your ankle” (HBP 336). Yet we know from the scribbled-out alterations in the textbook that Snape created this spell while using Advanced Potion-Making. This leads me to assume that he skipped a year and was probably accompanied by Lily, the other star student.
By this point in Snape’s teenage years, he and Lily are starting to grow apart. He has been accepted by the group of young Death Eaters, and she repeatedly voices her distaste for his friends. Potions have always been something that drew them together, no matter what, and Snape starts to throw himself into the subject more than ever. He spends all his free time poring over the book, experimenting with potions on his own, and trying to impress her in class with all the new instructions he has written for her to use. This only leads to more friction, however, as Lily’s voice and creativity are sidelined and she feels like a cheater for using work that’s not her own. The exams at the end of the year come up, and Snape insists that Lily borrow the book to use for her studying.
They are partway through their exams when everything falls apart. Snape, embarrassed and ashamed, lashes out and calls Lily a Mudblood. Lily tells Snape she’s done giving him second chances. Lily is still stuck with the book and – wanting to get rid of all reminders of their friendship – decides to stick it in the bottom of a cupboard in the Potions classroom.
Years pass. Snape becomes the Potions master but never bothers to search through the old textbooks. He’s not a big proponent of textbooks anyway, preferring to write his own carefully curated instructions on the blackboard. It isn’t until Snape leaves the dungeons and Slughorn returns to the castle that the cupboard is opened again, and Harry finds the book.
We can only imagine the emotions Snape must have felt when he realized that Harry had found his old textbook, especially knowing who had possession of it last. On the one hand, he must have been tempted to turn Harry in, especially since the way Harry was abusing the information was reminiscent of James. On the other hand, he first starts to suspect Harry of using the book when Slughorn compares Harry favorably to his mother (HBP 319). He ends up responding to both: punishing Harry for using his spells and also wanting Harry to learn his story and appreciate his work.
Snape’s story and Lily’s story are inextricably intertwined, and it is impossible to discuss one without considering the other. Harry thinks he understands Snape and the Half-Blood Prince at the end of the sixth book, but he has no idea that the real mystery of Snape’s identity always comes back to Harry’s mother.