It's been years since J.K. Rowling closed the book on her most famous character — though that hasn't stopped her from tossing fans new tidbits about the world of Harry Potter since. But there are still plenty of surprises contained in the Harry Potter series for new readers to discover, as well as a lot of burning questions still up in the air among die-hard fans.
So, in honor of those muggles who know everything about the series from Arithmancy to Xenophilius Lovegood and still have lingering questions — and also for readers who are diving in for the first time — here are the best secrets and most confusing, unexplained plot points in the entire Harry Potter series.
(Editor's note: We're covering the seven main books only — we're not gonna touch Cursed Child or anything released on Pottermore. Obviously, there are spoilers for the series below.)
Harry Potter and the Sorcerer's Stone
Arabella Figg is actually a squib: In the first Harry Potter book, it's revealed that Harry is often forced to spend time with a severely un-fun neighbor while the Dursleys go on fun trips without him. It's not until the fifth book in the series that we realize Mrs. Figg is a squib, a non-magical witch, and has been tasked with keeping an eye on Harry on behalf of Dumbledore and the rest of the Order of the Phoenix.
That snake at the zoo is probably not Nagini: A fan theory suggests that the snake that Harry frees at the zoo in Sorcerer's Stone is the same snake as Nagini, Voldemort's BFF that also becomes a Horcrux — but we're gonna go ahead and call BS on that theory. Not only are there no clues to support it in the books, it also doesn't make sense that a snake that owes Harry a favor would team up with his greatest enemy.
"Erised" is "desire" backwards: Um, duh. Harry Potter was only 11 in the first book, so let's forgive him for not figuring out that the mirror that shows you a vision of what you want most in the world is conveniently named the Mirror of Erised, aka the Mirror of Desire. Pretty chill.
Lingering questions and concerns:
What's up with Hagrid? Hagrid definitely does some illegal magic in the first book in the series, using his "umbrella" to give Dudley a pig's tail. But we know that Hagrid was kicked out of Hogwarts, and he's technically not allowed to do magic. So what's up with that? Why wasn't Hagrid exonerated when it was revealed he didn't actually open the Chamber of Secrets? Does anyone care that he still has his broken wand hidden in his umbrella? What, exactly, are the rules that govern who can and can't perform magic? Are witches and wizards who don't graduate from a magical academy forbidden from doing magic?
Why don't they teach anything else at Hogwarts? Harry and the gang arrive at Hogwarts when they're only eleven, and they're immediately expected to write essays. Who's teaching them to write? Are there any non-magic classes offered at Hogwarts? What about algebra or creative writing? Do they graduate from Hogwarts knowing how to turn a teacup into a mouse but not understanding basic cell biology? Did wizard-born kids go to muggle schools before Hogwarts?
What's up with wizard money? The first Harry Potter book introduces a lot of basic details about the wizarding world — which means that it also brings up a lot of logistical questions, many of which are too small and specific to bring up. But one pressing question that must be addressed is wizarding money: Why is it so weird? There are 17 Sickles in a Galleon and 29 Knuts in a Sickle. Why?
What about Harry's grandparents? In the first book Harry discovers (some of) his family story, as well as his family wealth, but it's never explained why none of Harry's grandparents, on either side, are still around. It becomes clear over the course of the series that Aunt Petunia is Harry's only living blood relative, but did Harry's grandparents die peacefully of old age? Or were they casualties of the devastating war that divided the wizarding world around the time of Harry's birth?
What's up with wizard religion? Everyone at Hogwarts seems to celebrate Christmas and not really any other holidays (except Valentine's Day) — which begs the question, do witches and wizards have religion? Do they celebrate Christmas just for fun? It seems as though there's pretty clear evidence of some kind of afterlife for wizards, but is there any particular unified belief system in the wizarding world?
Harry Potter and the Chamber of Secrets
The Harry and Ginny ship sets sail: This book is the one that really lays the groundwork for Harry and Ginny's future relationship — it's the first one in which she's at Hogwarts with her older brother, and (spoiler alert!) when he saves her at the end, it's one of the only major scenes the two have together until they officially get together in the sixth book.
Keep an eye on the dark objects: Book two introduces some key objects that come into play later in the series: the Hand of Glory and the vanishing cabinet that Malfoy will use in Half-Blood Prince.
Tom Marvolo Riddle: The second book in the series also begins to flesh out the backstory of Tom Riddle, aka Lord Voldemort, whose past won't be fully revealed for a while. But meeting the ghost of Riddle — brought to life by the power of the diary Horcrux — helps humanize the villain who, in the first book, was just a scary face with an evil agenda.
Expelliarmus: Damn, y'all, this disarming spell has legs. It makes its first appearance in the second book, and then Harry proceeds to use it at every conceivable opportunity for the next five installments — even in his final battle against Lord Voldemort.
Lingering questions and concerns:
Why can't anyone fix Harry's eyes? Chamber of Secrets delves into some of the powers of magical healing — for example, Madame Pomfrey is able to fully regrow Harry's bones after Gilderoy Lockhart removes them, and she's also able to wake the petrified students from their comas by brewing a draught made from mandrake roots. But why can't anyone, over the course of the whole series, fix Harry's eyes so he doesn't need glasses? Is it because his poor eyesight is a result of being attacked by Voldemort as a baby, like his magical scar? Let's hope that's the reason, otherwise it's pretty annoying that magical healers can shrink teeth and grow bone but not fix nearsightedness.
Can the Obliviate charm be reversed? Obliviate is another handy spell that first appears in Chamber of Secrets, and will come back again and again in the series. It's often used to wipe muggles' memories of magic, which seems a little ethically suspect. But a burning question is, once an Obliviate spell is cast, can it ever be reversed? it seems that, perhaps, under normal circumstances it can, because Lockhart's severe memory loss is a result of a backfiring spell from a broken wand. But if memory wiping is permanent, then when Hermione erases her parents' memories of her for their own protection in the final book, it's for good. That's tragic.
Why don't wizards ever borrow muggle technology? Chamber of Secrets introduces Arthur Weasley's love of muggle technology — but he's a curious quirky dude. In general, wizards ignore muggle technology and that seems like it might be a mistake. After all, wouldn't ballpoint pens be easier than quills and ink, especially when people spilling ink is a recurring problem over the course of the series? And wouldn't phones be easier than talking into a fireplace?
How sad is Moaning Myrtle's story? This isn't exactly a lingering question, it's more just a super sad story that doesn't immediately come across as super sad. But think about it — Myrtle died at school as a teen in a tragic attack and then was stuck (forever?) in the bathroom where she was killed. Did her parents come visit her there? Did they sue Hogwarts for millions of galleons? Did they die of old age while she was stuck as a child-ghost?
Harry Potter and the Prisoner of Azkaban
Sirus Black is back: Sirius Black is the titular character in the third book, and a major player in the series, but Prisoner of Azkaban isn't actually the first time we hear his name. He was first mentioned all the way back in the first chapter of the first book, when Hagrid arrives with the infant Harry to drop him off at the Dursley's, he shows up on a flying motorcycle and tells Dumbledore, "Young Sirius Black lent it to me." Gives you shivers to read it now, right?
Stan Shunpike: Poor Stan. He shows up for the first time in Prisoner of Azkaban as the driver of the Knight Bus, but that isn't the last time we see him. He pops up again in the next book, trying to impress a group of Veela, and he later shows up as a Death Eater, clearly acting under the Imperius curse. Stan is a helpful stand-in for a mundane wizard, capable of magic (we think) but mostly just a causality of wizarding affairs beyond his comprehension.
Lupin's name: Remus Lupin is twice named for wolves — "Remus" is a mythic founder of Rome who was raised by a wolf, and "Lupin" comes from the Latin word for wolf. So, duh, he's a werewolf. Names like Lupin's beg the question: Did his name predict his destiny, or can J.K. Rowling just not resist giving her characters such on-the-nose names?
Why don't Harry and the gang ever become animagi? This seems like a bummer of a missed opportunity. We learn about animagi in the third book, and find out that James Potter and his friends all gained the ability to turn into animals so they could hang with Lupin while he was being a werewolf. If a wizard as lame as Peter Pettigrew could go through the arduous process of learning to become an animagus (and then stay one for years), then couldn't Harry, Ron and Hermione figure it out? Imagine how fun it would have been to read about them turning into character-appropriate animals.
Harry Potter and the Goblet of Fire
We learn a lot from the Quidditch World Cup: The Quidditch World Cup is one of Harry's first forays into the parts of the wizarding world that exist beyond his school and Ron's home. Beyond laying the groundwork for some of the twists and turns that unfold over the course of the fourth book, Harry's time at the world cup also explains a lot about details of the magical world — like the portkeys that wizards use to get around, and the various spells and enchantments that keep muggles from accidentally finding out about magic.
Krum has a Gregorovitch wand: Here's a little moment that won't come back until the final book: When Ollivander is testing out the wands belonging to all four competitors in the Triwizard Tournament, he briefly notes that Krum's is a Gregorovitch creation. Gregorovitch, a famous wand-maker, returns in the final Harry Potter book — when Voldemort tries to track him down to get answers about the mythical Elder Wand.
The Room of Requirement makes an appearance: The Room of Requirement, a magical room in Hogwarts that offers itself up to people in need and automatically fills itself with useful supplies, makes its first appearance in Goblet of Fire. Dumbledore casually remarks to Harry that one night, when he needed the bathroom, he stumbled into a room full of chamber pots — but he's never been able to find it again. We'll find out later that this is typical of the Room: It makes itself available only when someone genuinely needs it.
Bill and Fleur have a moment: When Bill Weasley comes to watch Harry compete in the Triwizard Tournament, he catches the attention of Beauxbatons champion Fleur Delacour, who shoots him a flirty look. It may seem insignificant at the time — until we watch them fall in love and get married by the seventh book.
Lingering questions and concerns:
Does Mad-Eye Moody see everyone naked? Alastor "Mad-Eye" Moody is a paranoid auror with a magical eye that allows him to see through most stuff, it seems like, including closed doors. So does that mean he sees everyone naked? All the time? And when Barty Crouch Jr. is disguised as Moody, does he see everyone naked too?
Interspecies logistics: It's revealed at one point in Goblet of Fire that Fleur Delacour is part Veela. We already know that Hagrid (and probably Madame Maxine too) is part-giant. So what, exactly, are the "rules" surrounding magical species having babies together? It makes sense that J.K. Rowling wouldn't delve into the specifics of this, but you've got to wonder — could someone be a half-wizard half-centaur? What about part-merperson?
Harry Potter and the Order of the Phoenix
Notice that mysterious locket? Early in Order of the Phoenix, Harry, his friends, and various members of the Order are gathered at Number 12, Grimmauld Place, in London, which is the Black family home. As they're cleaning up the dusty house, the crew finds a host of vaguely sinister magical objects, including "a heavy locket that none of them could open, a number of ancient seals, and, in a dusty box, an Order of Merlin, First Class, that had been awarded to Sirius's grandfather for 'Services to the Ministry.'" Did you catch that, or did it go by too quickly? The heavy locket that no one could open was actually, as we'll learn in Deathly Hallows, Salazar Slytherin's heirloom, which had been turned into a Horcrux by none other than Voldemort himself. It sure would have saved them some time if they had known that in the fifth book.
That "familiar" barman at the Hog's Head: With Delores Umbridge slowly taking over Hogwarts, Harry and his rebellious friends schedule a meeting of the D.A. at the Hog's Head, one of Hogsmeade's seedier locales. The barman at the Hog's Head, "was a grumpy-looking old man with a great deal of long gray hair and beard. He was tall and thin and looked vaguely familiar to Harry." The reason he looks familiar to Harry is because, as we find out in the final book, he's actually Aberforth Dumbledore, Albus' brother. Before this point, he was mentioned only in passing and mostly as a joke.
What's up with the veil? Sirius Black dies when he is killed by his cousin, Bellatrix Lestrange, during the battle at the Ministry of Magic, and falls through a mysterious veil — seemingly into some kind of afterlife. So is that veil some kind of portal to the world beyond? Does it lead to the same place that Harry briefly visits in the seventh book? We've seen evidence of some kind of afterlife before — in Goblet of Fire, Voldemort's wand emits shadow versions of people he's killed, including Harry's parents. But are all dead people living in some sort of Heaven-type afterlife together? Or is it more situation-specific, with special circumstances that bring people's spirits back into the world of the living? There's also the confusing question of talking paintings of real people, but we'll get to that later.
Harry Potter and the Half Blood Prince
We've seen bezoars before: The bezoar, the magic little stone that Harry uses to save Ron's life when he's poisoned in Slughorn's office, has come up before. In fact, Snape asked Harry where he would find a bezoar in his very, very first potions class all the way back in Sorcerer's Stone. Bezoars are mentioned again, very briefly, in another potions class in Goblet of Fire. If Harry (and us) had been paying attention, he would have realized that bezoars were important long before reading about them in Snape's old potions book.
Voldemort's past: Harry's lessons with Dumbledore teach him more and more about Voldemort's past and his time at Hogwarts, filling in some of the plot points that had been hinted at in previous books. Although it's been clear throughout the series, it becomes more apparent than ever in Half Blood Prince that they are each other's foils completely — right down to their completely opposing reactions to childhood trauma. Years of negligence turned Voldemort into a coldhearted sadist and Harry into a scrappy and lovable orphan.
Lingering questions and concerns:
What, exactly, is the timeline of Hogwarts graduating classes? Peeks back into Voldemort's life tell us a little more about who was at Hogwarts at what times, but it's still kind of confusing. Hagrid and Voldemort (and Moaning Myrtle) overlapped, and Dumbledore and Slughorn were both professors there when Voldemort was a student. James and his crew overlapped with Snape, obviously, and Lucius Malfoy was a little bit older, but how much time passed between Voldemort's graduation and Snape's arrival at Hogwarts?
Drugs and alcohol in the wizarding world: Professor Trelawney is strongly implied, in Half Blood Prince to have, if not a drinking problem, then at least a prominent habit. Winky the house elf definitely had a problem with butterbeer, too. So it seems as though addiction is a problem in the magical world too. Despite the implications that some drinks, like Firewhiskey, aren't available to Hogwarts students, there doesn't seem to be a legal drinking age for wizards. Are there any rules around wizards and alcohol? What about other mind-altering drugs? You'd think that the wizarding world would be chock-full of magical illicit substances that the Ministry of Magic would be eager to regulate.
Felix Felicis: This potion, also called "liquid luck," is pretty amazing. The side effects also seem pretty negligible when compared with the benefits. So why don't Harry and company ever put a little more effort into trying to get more than a single dose over the course of the whole series? Even if the process behind making it is too complicated and long for Harry, Ron and Hermione, couldn't the Order of the Phoenix throw its considerable resources into acquiring another bottle or two of this very awesome potion?
Harry Potter and the Deathly Hallows
Dumbledore was lying about those socks: Deathly Hallows offers us, at long last, more backstory for Dumbledore, something we never got while he was still alive. Harry finally realizes, after learning about the horrible way in which his family was ripped apart, that Dumbledore wasn't telling him the truth when he said, all the way back in Sorcerer's Stone, that when he looked into the Mirror of Erised, it showed him holding a nice pair of wool socks. Dumbledore's deepest desire was never socks, but explaining what it actually was would have been a lot for the then-11-year-old Harry to handle.
Lingering questions and concerns:
Why hasn't Harry ever heard of Grindelwald? Was no one paying attention their magical history classes at Hogwarts? How could Harry and his friends not know about this powerful wizard whose duel with Dumbledore is so well-known that it's included on Dumbledore's chocolate frog card?
How do the magical paintings work? After the battle of Hogwarts, Harry goes to the headmaster's office to confer with the portrait of Dumbledore. And talking to Dumbledore's portrait seems a lot like talking to the actual, living Dumbledore. So if having a magical portrait of yourself allows your family and friends to have a version of you around forever, why doesn't everyone do this? Now Harry can just ask Dumbledore's portrait all the things he wanted to ask the real Dumbledore!