Looking at this answer just now, I got to thinking about the writing on the back of his old Potions book.

There’s nothing to indicate that the school book in question did not start out as being simply Snape’s own book, bought at Flourish and Blotts like pretty much all new school books; so when he started using it in Potions class during his sixth year at Hogwarts, the book would have been new and have no one else’s scribbles and names in it. (Edit: Actually, as Au101 points out in the comments below, the date in the book is nearly 50 years before HBP is set, which is long before Snape’s time at Hogwarts; so this doesn’t seem to be true. I can recall no mention of any non-Prince scribbles in the book, though—or indeed of any previous owner writing their own name—so this probably doesn’t change much for the purposes of the present question.)

We also know Snape is relatively unpopular at Hogwarts, except (usually/sometimes) with Lily and (probably) with his Slytherin mates and fellow Death Eaters-to-be. A group of friends that tend to put quite a bit of stock in pure-bloodedness. As far as is generally speculated (though there is no canon either way to my knowledge), Snape never told any of his friends (except probably Lily who at least vaguely knew his parents) that he was half-blood.

It seems quite safe to assume that Snape would have had Potions together with at least the other Slytherins in his year, and presumably also with students from one or more of the other houses.

It also seems quite safe to assume that, as in the real world, Hogwarts students occasionally share books, borrow each others’ books, get each others’ books mixed up by accident, or in some other way happen to look at/in other students’ school books. That certainly happened to me many a time when I was in school.

Perhaps exactly for this reason, it’s common practice for students to write their name in their books, to show whose book it is. Snape here chose to write “This book is the property of the Half-Blood Prince” on the back of his book, rather than simply putting his name on it.

Considering the kind of home-made spells he jotted down in that book, it’s perhaps not entirely surprising that he didn’t want his own name on it for any teacher to read. But he could have thought of a better nickname for himself—one that didn’t give away his half-blood status, for example.

There would be a fairly substantial risk of one of his Death Eater-to-be mates at some point during the year (or years, if the same book is used in the seventh year) coming across this inscription of ownership one way or another. (S)he would probably wonder, and presumably also ask Snape, what in the blazes he meant by calling himself a ‘half-blood prince’—which would at the very least lead to some awkwardness in that particular circle of friends, and at worst possibly even leave Snape ousted completely, and essentially entirely friendless.

Running a risk like that seems quite out of character for someone who’s usually as cautious, withheld, and calculating as Snape is portrayed as being.

So why did Snape write that his Potion book belonged to the ‘Half-Blood Prince’ for anyone in class to see? Why not either think of another, less incriminating, nickname; or not commit the nickname to writing?

There’s definitely no canon answer for this in the books. Has Rowling ever mentioned it? Has it ever been mentioned in any of her other writings? I’m looking for in-universe answers, primarily canon ones if possible. Well-argued speculation is all right, too, if there is nothing in canon (as I suspect there isn’t).

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    Because if he hadn't then book 6 would be called Harry Potter and Severus Snape.
    – CHEESE
    Commented Feb 14, 2016 at 2:18
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    @CHEESE He could have called himself the ‘Prince of Darkness’ (referring to his regular choice of color coordination when dressing) or something. I’m sure he could have come up with a cool-sounding nickname that didn’t actually give his blood status away. Commented Feb 14, 2016 at 2:22
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    I don't think he had thought of that. If he had, why didn't he use that over Half blood Prince?
    – CHEESE
    Commented Feb 14, 2016 at 2:23
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    @Au101 I suppose it doesn't really matter much, no—I was thinking it gave him a plausible excuse (“Oh, that must have been a previous owner, don't know what that is”), but it's described in the book as definitely being his own handwriting, so that excuse wouldn't really work very well after all. Commented Feb 14, 2016 at 3:17
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    I would think his being half-blood would be known... after all, his last name wouldn't be one of the known pure blood names. And as genealogy-obsessed the pureblood movement is, it seems unlikely they wouldn't have realized. Snape would have 'made up for' his less than pure heritage by openly decrying his father's muggle heritage and playing up his mother's, agreeing with their prejudices and 'overcoming' his origins. So if he can't hide his half-blood status, it might be better to openly claim it so its harder to use against him.
    – Megha
    Commented Feb 14, 2016 at 3:41

2 Answers 2


I have a very small thought, although it doesn't really strike at the heart of the question of why a budding Death Eater would craft such a nickname, however:

We know that Advanced Potion Making is the set book for Harry in his sixth year and that he has to send off for a copy, which suggests it is only used from the sixth year onwards. There's a small chance, of course, that Harry and Ron both binned their old potions books after failing to get Os in their OWLs and then had to order new ones, but Advanced Potion Making does not appear on any previous book lists we get to see.

Although it is possible that the syllabus changed between Snape's time and Harry's time, I'm fairly confident that Advanced Potion Making would have been a sixth year text when Snape was at school.

Now, as you allude to, one of the spells contained within Advanced Potion Making was Levicorpus and we are clearly supposed to see this as a spell of Snape's own creation:

Sitting up in bed, Harry turned the book sideways so as to examine more closely the scribbled instructions for a spell that seemed to have caused the Prince some trouble. There were many crossings-out and alterations, but finally, crammed into a corner of the page, the scriblle:

Levicorpus (n-vbl)

Harry Potter and the Half-Blood Prince - p.224 - Bloomsbury - Chapter 12, Silver and Opals

However, in The Order of the Phoenix, we see James use Levicorpus against Snape and Lupin comments:

'Oh, that one had a great vogue during my time at Hogwarts,' said Lupin reminiscently. 'There were a few months in my fifth year when you couldn't move for being hoisted into the air by your ankle.'

Harry Potter and the Half-Blood Prince - p.315 - Bloomsbury - Chapter 16, A Very Frosty Christmas

And, indeed, we see James Potter cast the spell right after an OWL exam in his and Snape's fifth year.

Which leads me to conclude that Snape was using this book privately for his own, extra-curricular study and when he was jotting in it and doodling in it and writing his nickname on it, it was not the set book for Potions lessons.

Which I hope contributes something towards the question of why he felt safe writing "Half-Blood Prince" on his textbook. It seems, indeed, to have been almost like a diary. I'm doubtful he ever (intended to) share(d) it with anyone.

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    So you're suggesting that he wrote the nickname on the book (perhaps several years) before it was ever a school book for him. That perhaps it was his mother’s old Potions book that he simply had in the same way that Hermione might have Hogwarts: a History in her room, for a bit of light reading; and that he perhaps had not even really initially considered that one day he'd have to use it as an actual school book in Potions class. That's an intriguing theory! It may also indirectly shed some light on why a budding Death Eater would choose such a nickname: if he did this perhaps in -> Commented Feb 14, 2016 at 3:42
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    -> his first or second year already, he wouldn't be a budding Death Eater yet. He may have just been starting to mix with the blood supremacist crowd and secretly taken some perverse pleasure in coming up with a nickname that highlights what really sets him apart from his new friends (and which of course he'd never tell them, but feels he can write in his mum’s old book, stashed away under his bed). Commented Feb 14, 2016 at 3:44
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    @JanusBahsJacquet Yes exactly. To quote Dumbledore "an admirably succinct summary" - although I confess your speculations about how he came to choose the name didn't really occur to me, but it's a fair theory. Megha's comment above is actually very interesting. Death Eaters hate blood traitors. Similarly, being a blood traitor in the opposite way could be a very good status symbol. I'm from a pretty middle class family and I went to a pretty left wing university. I once got called a "class traitor" in a positive way :P
    – Au101
    Commented Feb 14, 2016 at 3:48
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    He actually explained it to Harry I believe. He didn't want people to know it was his book, if someone were to get their hands on it. He was using the book as not only a way to study, but also to note other things that he became aware of (as methods in potion crafting), or, more importantly Dark Magic like Sectumsempra
    – Oak
    Commented Feb 14, 2016 at 4:18
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    @Oak I'm not sure about all this. He explained to Harry that he was the Half-Blood Prince and inventor of the spells, but that's it, as far as I can find. I don't believe he gave Harry a rundown of why he was named like that or why he wrote it on his book or anything, but if you can find some quotes do please put them up! :) I can find no reason to believe that Voldemort knew the "Half-Blood Prince" title and while I'm convinced Lily knew he was half-blood, again, I can't see any reason to think she knew his nickname
    – Au101
    Commented Feb 14, 2016 at 16:11

Snape came up with the nickname "Half-Blood Prince" not because he was halfblood in the traditional sense (half wizard, half Muggle) but because he was a halfblooded Prince. His mother's maiden name, before she married Tobias Snape, was Eileen Prince.

After the events of the sixth book, the trio theorize this based on the information she dug up through the year:

"Well, yes," said Hermione. "So...I was sort of right. Snape must have been proud of being 'half a Prince', you see?[...]"

"Yeah, that fits," said Harry. "He'd play up the pure-blood side so he could get in with Lucius Malfoy and the rest of them..."

-Harry Potter and the Half-Blood Prince, The White Tomb Blockquote

Snape was very proud of his mother's side of the family, the magical side. Both of Snape's parents weren't particularly loving towards him, but Snape definitely liked his mother more because, as we see in Snape's memory in Order, he was terrified of his abusive father. On top of that, his father was a Muggle, something scorned upon in the House that he had been Sorted into.

Plus, Snape was a private, quiet person anyway. He was that kid in the corner that everyone ignored when they weren't picking on him, again, as we see throughout Order. A lot of students thought he was creepy for his interest in the Dark Arts and gave him a wide berth too. I doubt he'd have been very chummy and sharing books. On the chance someone did come across his textbook, well, his name wasn't on it. If they caught it in his possession, he could simply claim the truth he was at odds with his father and wanted to associate himself with his mother's side.

Ron then asks why Snape didn't call Harry out on having his old Potions book, and Hermione guesses this:

"I don't think he wanted to associate himself with that book," said Hermione. "I don't think Dumbledore would have liked it very much if he'd known. [...]"

-Harry Potter and the Half-Blood Prince, The White Tomb

Later on, after Harry found his textbook, the reason that Snape didn't want to tell anyone that he was the Half-Blood Prince, even after he knew that Harry had it, was because it would link him to the book. As Hermione said, Dumbledore wouldn't have been happy to find out that Snape dabbled in so much Dark magic (though he probably did know, unbeknowst to the trio). Dumbledore would have been especially unhappy to know that the book had fallen into Harry's hands from Snape. Also, though this might be conjecture, Snape probably doesn't want to get in to anything reminding him of his school days with Harry.

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